WO2013007212A1 - La(fe,si)13-based magnetic refrigerant prepared from industrially pure mixed rare-earth, preparation method and uses thereof - Google Patents

Abstract

The present invention provides an La(Fe,Si)₁₃-based magnetic refrigerant prepared from industrially pure mixed rare-earth. The industrially pure mixed rare-earth is an intermediate product of rare-earth purification, a mixed rare-earth of La-Ce-Pr-Nd in natural proportions and containing impurities extracted from light rare earth ore, or a LaCe alloy in natural proportions and containing impurities extracted from light rare earth ore. The present invention also provides a preparation method and use for said refrigerant. The method comprises: using industrially pure mixed rare-earth as a raw material, smelting, then annealing same to obtain the La(Fe,Si)₁₃-based magnetic refrigerant. The impurities in the industrially pure mixed rare-earth do not affect a 1:13 phase formation and the appearance of a first order phase transition or metamagnetic transition behaviors, preserving the great magnetocaloric effect of the magnetic refrigerant. Using industrially pure mixed rare-earth to prepare a La(Fe,Si)₁₃-based magnetic refrigerant reduces dependence on high purity single rare earth raw materials, reduces refrigerant preparation costs and is of practical significance to materials development in magnetic refrigeration.

Description

La(Fe,Si) ₁₃ -based magnetic refrigeration material prepared from industrial pure mixed rare earth

 And preparation method and use thereof

The invention relates to a magnetic refrigeration material, in particular to a 1^(?^ _{13 13} -base magnetic refrigeration material prepared by using industrial pure mixed rare earth as a raw material and having a huge magnetocaloric effect, and a preparation method and use thereof.

 Rare earth metals are widely used, and the preparation of new magnetic refrigeration materials is inseparable from rare earths. The total weight of 17 rare earth elements in the earth's crust is 0.0153%, of which the content of cerium (Ce) is the highest, accounting for 0.0046%. The sum of four light rare earth elements of lanthanum (La), lanthanum (Ce), praseodymium (Pr) and yttrium (Nd) accounts for about 97% of the total rare earth content. At present, there are about 250 kinds of rare earth minerals, but only about 10 kinds of rare earth minerals are used. There are four kinds of minerals currently used for industrial extraction of rare earth elements, including light rare earth minerals such as fluorocarbons and monazite. China's rare earth resources are characterized by south and north light. Light and rare soils are mainly stored in Inner Mongolia in northern China. Heavy rare earths are mainly stored in the Nanling area in southern China. It is currently known that the world's largest light rare earth ore-fluorocarbon antimony ore is located in the Bayan Obo mine in Inner Mongolia, China. As a by-product of the Kailuan iron ore mine, it is opened together with monazite. The total amount of rare earth in bastnasite is about 74.8%, of which La is 22.6%, Ce is 53.3%, Pr is 5.5%, Nd is 16.2%, Sm is 1.1%, Eu is 0.3%, Gd is 0.6%, Tb is 0.1%, Dy is 0.2%, Y is 0.1%; the total amount of rare earth in the monazite ore is about 65.1%, of which La is 27.7%, Ce is 40.2%, Pr is 6.9%, Nd is 16.5%, and Sm is 2.9%. Eu is 0.3%, Gd is 2.2%, Tb is 0.1%, Dy is 0.4%, Er is 0.1%, Yb is 0.7%, and Y is 2.1%. These rare earth scores depend on fluctuations in different minerals.

 The energy consumption of the refrigeration industry accounts for more than 15% of the total energy consumption of the society. At present, the gas compression refrigeration technology commonly used has a Carnot cycle efficiency of only about 25%, and the gas refrigerant used in gas compression refrigeration destroys the atmospheric ozone layer and causes a greenhouse effect. Exploring non-polluting, green and environmentally friendly refrigeration materials and developing new low-energy, high-efficiency refrigeration technologies are urgent issues in the world today.

Magnetic refrigeration technology is characterized by environmental protection, high efficiency, energy saving, stability and reliability. It has attracted worldwide attention in recent years. Several types of room temperature and even high temperature giant magnetocaloric materials discovered in the United States, China, the Netherlands, and Japan have greatly promoted people's expectations for green magnetic refrigeration technology, such as: Gd-Si-Ge, LaCaMn0 ₃ , Ni-Mn-Ga, La(Fe,Si) ₁₃ -based compound, MnAs-based compound, and the like. The common feature of these new giant magnetocaloric materials is that the magnetic entropy change is higher than that of the traditional room temperature magnetic refrigeration material Gd, the phase transition property is one stage, and most of them exhibit strong magnetocrystalline coupling characteristics, and the magnetic phase transition is accompanied by significant The phase change of the crystal structure occurs. These new materials also exhibit different material characteristics. For example, the Gd ₅ (Si ₂ Ge ₂ ) alloy discovered by the American Ames National Laboratory in 1997 has a huge magnetocaloric effect, and the adiabatic temperature change ΔΤ is higher than 30% of the elemental rare earth Gd. The magnetic entropy becomes higher than 100% of Gd; however, such materials often require further purification of the raw material Gd during the synthesis process. The commercially available Gd purity is 95-98 at.% (atomic ratio), and the price is 200 USD/kg. The Gd ₅ (Si ₂ Ge ₂ ) alloy prepared by commercial purity Gd does not have a giant magnetocaloric effect; if the raw material Gd is purified to > 99.8 at. % (atomic ratio), the Gd ₅ (Si ₂ Ge ₂ ) side is synthesized. The giant magnetocaloric effect, and the price of Gd with a purity of > 99.8 & 1.% is 4,000 USD / kg, which greatly increases the preparation cost of the material. Studies have also shown that the presence of impurities in raw materials (such as 0.43at.% C, 0.43at.%N, 1.83at.%0) or the introduction of a small amount of C elements will lead to the first phase transformation of Gd ₅ (Si ₂ Ge ₂ ). The feature disappears and the giant magnetocaloric effect disappears (J. Magn. Magn. Mater. 167, L 179 (1997); J. Appl. Phys. 85, 5365 (1999)). Among other new materials, the raw material of the MnAs-based compound is toxic, and the NiMn-based Heusler alloy has the characteristics of large hysteresis loss and the like.

Among the new types of materials discovered in the past decade or so, La(Fe,Si) ₁₃ -based compounds, which are widely accepted internationally and are most likely to achieve high temperature and even room temperature magnetic refrigeration applications, have low raw material prices. The phase transition temperature, phase transition property, and hysteresis loss can be adjusted with the composition, and the magnetic entropy near room temperature is twice as high as that of Gd. La(Fe,Si) ₁₃ -based magnetic refrigeration materials have been used in prototype testing in several countries, for example: In 2006, the American National Aerospace Technology Center (Astronautics Technology Center, Astronautics Corporation of America) first introduced La ( Fe, Si) ₁₃ -based materials are used in prototype tests. The preliminary results prove that their refrigeration capacity is better than Gd. Further, the company's latest prototype test results in 2010 prove that: room temperature refrigeration capacity of La(Fe,Si) ₁₃ -based materials Can achieve 2 times Gd.

Studies have shown that the phase transition properties of La(Fe,Si) ₁₃ based compounds can vary with the adjustment of the components. For example, the phase transition property of a compound with a low Si content is generally one stage. As the Co content increases, the Curie temperature rises, the first-order phase transition property weakens, and gradually transitions to the second stage, and the hysteresis loss gradually decreases (the second-order phase transition has no hysteresis). Loss), however, due to changes in composition and exchange, the magnitude of the magnetocaloric effect also decreases. The addition of Mn reduces the Curie temperature by affecting the exchange effect, the first-order phase transition property is weakened, the hysteresis loss is gradually reduced, and the magnitude of the magnetocaloric effect is also decreased. On the contrary, it has been found that the replacement of La by a small rare earth magnetic atom (e.g., Ce, Pr, Nd) enhances the first-order phase transition property, the hysteresis loss increases, and the magnetocaloric effect increases. It has also been found that the introduction of interstitial atoms (eg C, H, B, etc.) with small atomic radii increases the Curie temperature and causes the magnetocaloric effect to occur in the higher temperature range, for example, in the formula LaFen.5Sii.5Ha The phase change temperature (magnetic) when the content of interstitial atom H increases from α = 0 to α = 1.8 The peak temperature of the thermal effect) rises from 200K to 350K. It is expected that a first-order phase-change La(Fe,Si) ₁₃ -based compound having a giant magnetocaloric effect can be used for practical magnetic refrigeration applications and achieve an ideal refrigeration effect.

Previous reports have shown that La(Fe,Si) ₁₃ -based compounds use commercial elemental elements in the preparation of rare earth raw materials. It is known that the earth's crust is rich in rare earth elements of La and Ce. The abundance of Ce is the highest, followed by Y, Nd, La, etc., and the natural composition of many rare earth ores is 20-30% for La and 40-60% for Ce. And other rare earth and non-rare earth mixtures. It is much easier to obtain a LaCe alloy in a ratio of about 1:2 in the purification process than to obtain elemental La and Ce, respectively. The price of commercial LaCe alloys is also much cheaper than the commercial elemental elements La, Ce. If a commercial LaCe alloy can be used as a raw material, a giant magnetocaloric La(Fe,Si) ₁₃ -based compound having a NaZn ₁₃ structure can be prepared, which has important practical significance for the development of magnetic refrigeration applications.

In addition, in fact, in the natural world, four light rare earth elements such as La, Ce, Pr, and Nd are often stored in the same mineral. For example, they account for about 98% of the rare earth in the bastnasite ore, accounting for the monazite ore. The proportion of rare earths also reached about 91%. Industrially, the La-Ce-Pr-Nd mixed rare earth ratio obtained from these ores is much easier to obtain the elemental La, Ce, Pr, and Nd, respectively. Therefore, the industrially pure La-Ce-Pr-Nd mixed rare earth and Compared with elemental rare earths, there is an absolute price advantage. For example, the prices of elemental rare earth metals La, Ce, Pr, and Nd in 2011 are about RMB 250,000/ton, about RMB 350,000/ton, about RMB 1.7 million/ton. , about 1.8 million yuan / ton, the average price is about 1.025 million yuan / ton, and the price of mixed rare earth La-Ce-Pr-Nd is about 465,000 yuan / ton (quote from Baotou Rare Earth Enterprise Association http: //www.reht.com/?thread-1271-l.html )„If you can use this natural pure La-Ce-Pr-Nd blend with natural proportions extracted from minerals such as bastnasite or monazite. Preparation of La(Fe,Si) ₁₃ -based magnetic refrigeration materials using rare earths as raw materials will have great application prospects.

 Accordingly, it is an object of the present invention to provide an industrial pure mixed rare earth as a raw material.

1^^^) ₁₃ -base magnetic refrigeration material. Another object of the present invention is to provide a method for producing the above La(Fe,Si) ₁₃ based magnetic refrigeration material. A further object of the present invention is to provide a 1 comprising the ^ (? ^ ₀₁₃ magnetic refrigerating machine magnetocaloric material of the base. Still another object of the present invention is to provide a said La (Fe, Si) ₁₃ Magnetic yl The use of thermal effect materials in the manufacture of refrigeration materials.

 The object of the present invention is achieved by the following technical solutions.

The invention provides a La(Fe,Si) ₁₃ -based magnetic refrigeration material prepared by using industrial pure mixed rare earth as raw material, and the industrial pure mixed rare earth is extracted from light rare earth ore as a rare earth purified intermediate product. a La-Ce-Pr-Nd mixed rare earth having a natural proportion of impurities or a LaCe alloy having a natural ratio containing impurities extracted from a light rare earth ore having a NaZn ₁₃ type structure,

When the industrial pure mixed rare earth is an impurity-containing La-Ce-Pr-Nd mixed rare earth extracted from a light rare earth ore, the chemical formula of the material is:

 Wherein A is selected from one or more of the elements C, H and B,

 The range of X is: 0 < χ 0.5, preferably 0 < χ 0.3,

 The range of ρ is: 0 ρ 0.2,

 The range of q is: 0 q 0.2,

 The range of y is: 0.8<y 1.8,

 The range of α is: 0 α 3.0,

优选为纯度 > 98wt.%, 所述 La-Ce-Pr-Nd混合稀土中的杂质包括 Sm、 Fe、 Si、 Mg、 Zn、 W、 Mo、 Cu、 Ni、 Ti、 Th、 Y、 Ca、 Pb、 Cr、 C、 H、 O中的一种或多种； Wherein, the relative molar ratios of the three elements of Ce, Pr, and Nd are the natural proportions of Ce, Pr, and Nd in the La-Ce-Pr-Nd mixed rare earth, and the total number of moles thereof is X; In the Ce-Pr-Nd mixed rare earth, the molar ratio of the four elements of La, Ce, Pr, Nd is its natural proportion in the light rare earth ore, and the purity of the La-Ce-Pr-Nd mixed rare earth is >

Preferably, the purity is > 98 wt.%, and the impurities in the La-Ce-Pr-Nd mixed rare earth include Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb. One or more of Cr, C, H, O;

 When the industrial pure mixed rare earth is a rare earth-containing LaCe alloy containing impurities in a rare earth ore purification process, the chemical formula of the material is:

Lai _-xz Ce _x R _z (Fe i _-pq Co _p Mn _q ) 1 _3-y S i _y A _a ,

 Wherein R is selected from one or both of Pr and Nd elements,

 A is selected from one or more of C, H and B elements,

 The range of X is: 0 < x 0.5, preferably 0 < x 0.3,

 The range of z is: 0 z 0.5, and χ+ζ<1,

 The range of p is: 0 p 0.2,

 The range of q is: 0 q 0.2,

 The range of y is: 0.8<y<1.8,

 The range of a is: 0<a<3.0,

 Wherein, the purity of the LaCe alloy is >95 at.%, and the La:Ce atomic ratio in the alloy is a natural ratio of La:Ce in the light rare earth ore, preferably 1:1.6-1:2.3, impurities in the LaCe alloy Including Pr, Nd, Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr,

One or more of C, H, and O.

当所述工业 纯混合稀土为从轻稀土矿中提取的含杂质的具有自然比例的 LaCe合金时，所 述材料的化学通式为：

The invention also provides a preparation method of the above magnetic refrigeration material, the method comprising the following steps: 1) formulating raw materials according to chemical formula, when A in the chemical formula includes hydrogen element, preparing raw materials other than hydrogen according to a chemical formula, the raw material includes industrial pure mixed rare earth, and the industrial pure mixed rare earth is used as a rare earth purified intermediate product from light rare earth ore. Extracted La-Ce-Pr-Nd mixed rare earth with natural proportion or impurity-containing LaCe alloy with natural proportion extracted from light rare earth ore, when the industrial pure mixed rare earth is extracted from light rare earth ore When the rare earth-containing La-Ce-Pr-Nd is mixed with rare earth, the chemical formula of the material is:

When the industrial pure mixed rare earth is an impurity-containing LaCe alloy having a natural proportion extracted from a light rare earth ore, the chemical formula of the material is:

 2) preparing an alloy ingot by using an arc smelting technique, placing the prepared raw material in step 1) into an electric arc furnace, vacuuming, cleaning with argon gas, and smelting under argon gas to obtain an alloy ingot;

3) vacuum annealing the alloy ingot smelted in step 2), and then quenching in liquid nitrogen or water to obtain La _1-xz Ce _x R _z (Fe _1-M Co _p Mnq) _13- ySiyA _a having a NaZn ₁₃ structure. Or La _1-x (Ce, Pr, Nd) _x (Fe _1-pq Co _p Mn _q ) _13-y Si _y A _a magnetocaloric effect material;

 Wherein, when A in the above chemical formula includes a hydrogen element, the method further comprises the step 4): dividing the material obtained in the step 3) into a powder and annealing in hydrogen.

 The present invention also provides a magnetic refrigerator comprising the magnetic refrigeration material provided by the present invention or the magnetic refrigeration material produced by the preparation method provided by the present invention.

 The invention also provides the use of the magnetic refrigeration material or the magnetic refrigeration material produced in accordance with the method of the invention in the manufacture of a refrigeration material. BRIEF DESCRIPTION OF THE DRAWINGS

 The invention will be described in detail in conjunction with the following figures, in which:

y=0.2, 0.3 )样品室温下的 XRD 谱线。 Figure 1 is an embodiment

y = 0.2, 0.3) XRD line at room temperature.

 Figure 2 is a thermomagnetic (M-T) curve of a LaojCei Fen.sSiMCy (y = 0.2, 0.3) sample prepared in Example 1 under a 0.02 T magnetic field.

Figure 3 is a 1^. ₇ 6 produced in Example 1. .^6 ₁₁ . ₍ ^ ₁ . ₄ (^(=0.2, 0.3) The magnetization curve (MH curve) of the sample at different temperatures at different temperatures.

4 is a 1^ produced in Example 1. . ₇ 6. .^6 ₁₁ . ₍ ^ ₁ . ₄ ( =0.2, 0.3) The dependence of the magnetic entropy change AS on temperature under different magnetic field changes.

(χ=0·04, 0.06, 0.08 )样 品室温下的 XRD谱线， 其中 *号峰为未知杂相。 图 6为

(χ=0·04, 0.06, 0.08 )样 品在 0.02Τ磁场下的热磁 （Μ-Τ) 曲线。 Figure 5 is

(χ=0·04, 0.06, 0.08) The XRD line at room temperature, where the * peak is an unknown phase. Figure 6 is

(χ=0·04, 0.06, 0.08) The thermomagnetic (Μ-Τ) curve of the sample at 0.02 Τ magnetic field.

(χ=0·04, 0.06, 0.08 )样 品不同温度下升场过程的磁化曲线 （ΜΗ曲线） 和由 ΜΗ曲线 （图 7a, b, c) 导出的 Arrott图 （图 7d)。 Figure 7 is

(χ=0·04, 0.06, 0.08) The magnetization curve of the sample at different temperatures at different temperatures (ΜΗ curve) and the Arrott diagram derived from the ΜΗ curve (Fig. 7a, b, c) (Fig. 7d).

(χ=0·04, 0.06, 0.08 )样 品不同磁场变化下磁熵变 Δ S对温度的依赖关系。 Figure 8 is

(χ=0·04, 0.06, 0.08) The dependence of the magnetic entropy change Δ S on the temperature under different magnetic field changes.

9 is an XRD line at room temperature of a sample of Lao. _95-y Ce ₀₅ Pr _y Fe _1L5 Si _L5 (y=0.1, 0.5) prepared in Example 3, wherein the peak marked with * is an unknown impurity phase.

 Figure 10 shows the heat of a (y=0.1, 0.5) sample in a 0.02T magnetic field.

(y=0.1, 0.5)样品在 0-5T 磁场变化下磁熵变 AS对温度的依赖关系。 Figure 11 is

(y=0.1, 0.5) The dependence of the magnetic entropy change AS on temperature in the 0-5T magnetic field change.

Figure 12 is a 1^. ₈ 6 obtained in Example 4. ₂ ?6 ₁₁ . ₄ 81 ₁ . ₆ :6 ₀₁ ( 01=0, 0.2, and 0.4 ) The XRD line at room temperature, where the * sign is an unknown impurity.

( a=0、 0.2和 0.4 )样品在 0.02T 磁场下的热磁 （M-T) 曲线。 Figure 13 is

(a = 0, 0.2, and 0.4) Thermomagnetic (MT) curves of the sample at 0.02 T magnetic field.

(a=0、 0.2和 0.4 )样品在 0-1T 磁场变化下磁熵变 AS对温度的依赖关系。 Figure 14 is

(a = 0, 0.2, and 0.4) The dependence of the magnetic entropy on the temperature of the sample under the 0-1T magnetic field change.

Figure 15 is a graph showing the XRD spectrum of a sample of Lao. ₉ Ce _ai (Fe ₆ Co ₂ Mn ₀ . ₂ ) _13-y Si _y (y = 0.9, 1.8) prepared in Example 5 at room temperature. Unknown miscellaneous phase.

Figure 16 is a thermomagnetic (MT) curve of a sample of Lao. ₉ Ce _ai (Fe ₆ Co ₂ Mn ₀ . ₂ ) _13-y Si _y (y = 0.9, 1.8) prepared in Example 5 under a magnetic field of 0.02 T.

 Figure 17 is a sample of Lao.7Ceo.3Fen.5SiL5C 2Ho.45 prepared in Example 6: (a) a thermomagnetic (MT) curve at 0.02 T magnetic field; (b) a magnetic entropy change AS pair at 0-5 T magnetic field change Temperature dependence.

 Figure 18 is a sample of Lao.7Ceo.3Fen.5SiL5C 2Bao5Ho.55 prepared in Example 6: (a) Thermomagnetic (MT) curve at 0.02 T magnetic field; (b) Magnetic entropy change AS under 0-5 T magnetic field change Temperature dependence.

 19 is an XRD line of a La^Cea^Pr^Ndo.^wFen.sSiM sample prepared in Example 7, and the unknown impurity phase is indicated by an *.

Figure 20 is a graph of Example 7 prepared in Example ₇ . 6. _{. 21 (? 1¾. 2 ^} (1 .. 75) ,? 6 11. (^ Thermomagnetic _1.4 0.02 D sample at a magnetic field (MT) curve.

21 is a La^Cea^Pro^Nda^wFen^iM sample prepared in Example 7 at a 0-5T magnetic field. The change of magnetic entropy to AS under temperature is changed.

Figure 22 is a 1^. ₇ 6 produced in Example 8. .^6 ₁₁ . ₍ ^ ₁ . ₄ 0 ₎ . _{1 3⁄4} . _{9 The} sample 1 ^ line at room temperature, the unknown impurity phase is marked by *.

 Figure 23 is a thermomagnetic (M-T) curve of a La^Cec Fe^SiMQ H^ sample prepared in Example 8 under a magnetic field of 0.02 T.

 Fig. 24 is a graph showing the dependence of the magnetic entropy change AS on the temperature of the La^Cec Feu.sSiMCo.iH^ sample prepared in Example 8 under a 0-5T magnetic field change.

 Figure 25 is a XRD (X-ray diffraction) line of a sample of Lao. Ce Nd Fen.sSiwCy (y = 0, 0.1, 0.2) prepared in Example 9, wherein the * peak is derived from an unknown impurity phase.

Figure 26 is a Lao. ₇ (Ce, Pr, Nd) obtained in Example 9. . ₃ Fe _1L6 Si _L 4Cy ( y = 0, 0.1, 0.2 ) Thermomagnetic (MT) curve of the sample at 0.02 T magnetic field.

(y=0, 0.1, 0.2)样品 在不同温度下升场过程的磁化曲线 （MH曲线）。 Figure 27 shows

(y = 0, 0.1, 0.2) The magnetization curve (MH curve) of the sample during the field rise at different temperatures.

 Figure 28 is a graph showing the dependence of the magnetic entropy change AS on the temperature of Lao. Ce Nd Fen.sSiwCy (y = 0, 0.1, 0.2) prepared in Example 9.

( χ=0·02, 0.04, 0.06, 0.08, 0.1 )样品在室温下的 XRD谱线， 其中 *号峰来自于未知杂相。 Figure 29 is an embodiment

( χ = 0·02, 0.04, 0.06, 0.08, 0.1 ) The XRD line of the sample at room temperature, where the * peak comes from the unknown impurity phase.

FIG 30 is a Lao Example 10 was _{embodiment. 7 (Ce, Pr, Nd} ) 0. 3 (Fe 1-x Co x) 1L6 Si L4 (χ = 0 · 02, 0.04, 0.06, 0.08, 0.1) samples Thermomagnetic (Μ-Τ) curve at 0.02 Τ magnetic field.

(χ=0·02, 0.04,Figure 31 is an embodiment

(χ=0·02, 0.04,

0.06, 0.08, 0.1 ) The magnetization curve of the sample at different temperatures (ΜΗ curve) and the Arrott diagram derived from the ΜΗ curve (Fig. 31a, 31b, 31c, 31d, 31e) (corresponding to Fig. 31f, 31g, 31h) , 31i, 31j).

FIG 32 is a Lao Example 10 was _{embodiment. 7 (Ce, Pr, Nd} ) 0. 3 (Fe 1-x Co x) 1L6 Si L4 (χ = 0 · 02, 0.04, 0.06, 0.08, 0.1) samples The dependence of magnetic entropy change AS on temperature under different magnetic field changes.

 Figure 33 is a comparison of the XRD line at room temperature of Lao. Ce ^ Nd Fen.sSiMH hydride prepared in Example 11 and before hydrogen absorption, wherein the * peak is derived from the unknown impurity phase.

 Figure 34 is a comparison of the thermomagnetic (M-T) curve of Lao. Ce Nd Fen.sSiMH^ hydride prepared in Example 11 under a magnetic field of 0.02 T and before hydrogen absorption.

35a, b are the magnetization curves (MH curve) of the Lao. Ce Nd Fen.sSiMH hydride prepared in Example 11 at different temperature rise and fall fields, and before the hydrogen absorption, FIG. 35c shows that before hydrogen absorption, The relationship between the magnetic hysteresis loss and temperature. Figure 36 is a graph showing the dependence of the magnetic entropy change AS on the temperature of the Lao. Ce ^ Nd Fen.sSiMH hydride prepared in Example 11 under different magnetic field changes and before hydrogen absorption.

(α=0·1、 0.3和 0.5 ) 合金样品在室温下的 XRD谱线， 其中 *号峰为未知杂相。 Figure 37 is an embodiment

(α = 0.1, 0.3, and 0.5) The XRD line of the alloy sample at room temperature, where the * peak is an unknown impurity phase.

38 is Lao. ₈ (Ce, Pr, Nd) obtained in Example 12. ₂ Fe _1L 4Si _L6 B _a (α=0·1, 0.3 and 0·5) Thermomagnetic (Μ-Τ) curves of alloy samples at 0.02 Τ magnetic field.

(α=0·1、 0.3和 0.5 ) 合金样品在 0-1T磁场变化下磁熵变 AS对温度的依赖关系。 Figure 39 is an embodiment

(α=0·1, 0.3, and 0.5) The dependence of the magnetic entropy change AS on the temperature of the alloy sample under the 0-1T magnetic field change.

 Figure 40 is an XRD line of Lao. Ce i^Nd Feu.sSiMCaiH^ hydride prepared in Example 13 at room temperature.

Example 41 is prepared in an embodiment 13 ^ ₇ (^ 1 ^ (1) .. _{3? 611. (1} ^. _40). Thermomagnetic ₁ ¾. ₈ butoxy hydride in 0.02 of the magnetic field ( MT) curve.

 Figure 42 is a graph showing the dependence of the magnetic entropy change AS on the temperature of Lao. Ce i^Nd Fen.sSiMQ H^ hydride prepared in Example 13 under different magnetic field changes.

 Figure 43 is an XRD line at room temperature of La^Ce i^Nc FeasCoasMno n-ySiy (y = 1.8) prepared in Example 14, wherein the * sign is an unknown impurity phase.

Figure 44 is a magnetic field of Lao. ₉ (Ce, Pr, Nd) _i (Fe ₀ . ₆ Co ₀ . ₂ Mn ₀ . ₂ ) _13-y Si _y (y = 0.9 and 1.8) prepared in Example 14. Thermal magnetic (MT) curve underneath.

Figure 45 is a 1^. ₇ ( ^1^(1).. ₃ ?6 ₁₁ .^ _{1. 5} 0 ₎ . ₂ 8 obtained in Example 15. . . . Thermal magnetic (MT) curve of ₅ 3⁄4. ₅₅ hydride at 0.02 T magnetic field.

 Figure 46 is a graph showing the dependence of the magnetic entropy change Δ S on the temperature of Lao. Ce i^Nd Feu.sSiLsQ Bo.osHo^ hydride produced in Example 15. Detailed description of the invention

 To help understand the invention, some terms are defined below. The terms defined herein have the meaning commonly understood by one of ordinary skill in the art to which the invention pertains.

Unless otherwise stated, the "^211 ₁₃ type structure" or "1:13 structure" corresponding to the LaFe ₁₃ _ _x M _x used herein refers to a structure in which the space group is F. The Fe atoms occupy the two crystal positions 8b (Fe ¹ ) and 96i (Fe ¹¹ ), respectively, in a ratio of 1:12. La and Fe ¹ atoms constitute a CsCl structure. The La atom is surrounded by 24 Fe ¹¹ atoms, and the Fe ¹ atom is surrounded by 12 Fe ¹¹ atoms which constitute an icosahedron. Each Fe ¹¹ atom is surrounded by 9 nearest neighbor Fe ¹¹ atoms, 1 Fe ¹ atom and one La atom. For LaFe ₁₃ ^M _x (M = A1, Si) compounds, neutron diffraction experiments show: 8b position It is completely occupied by Fe atoms, and the M atoms and the remaining Fe atoms randomly occupy the 96i position.

 In the present invention, the terms "magnetic material", "magnetic refrigerating material" and "magnetothermal effect material" have the same meaning, and the three can be used interchangeably.

 In the present invention, the terms "impurity-containing" and "industrially pure" have the same meaning, and the two may be used interchangeably. For La-Ce-Pr-Nd mixed rare earths, "impregnated" or "industrially pure" means purity > 95 \¥1.%; for LaCe alloys, "impurity-containing" or "industrial pure" It means purity > 95 &1.%.

In one aspect, the present invention provides a La(Fe,Si) ₁₃ -based magnetic refrigeration material prepared by using industrial pure mixed rare earth as a raw material, and the industrial pure mixed rare earth is extracted from a light rare earth ore as a rare earth purified intermediate product. A La-Ce-Pr-Nd mixed rare earth having a natural proportion of impurities or a LaCe alloy having a natural ratio containing impurities extracted from a light rare earth ore.

 In a first embodiment of the invention, the industrially pure mixed rare earth is an impurity-containing La-Ce-Pr-Nd mixed rare earth having a natural proportion as a rare earth purified intermediate product extracted from a light rare earth ore. Preferably, the impurity-containing La-Ce-Pr-Nd mixed rare earth is a high Ce industrial pure mixed rare earth.

 In the above embodiment, the impurity-containing material extracted from the light rare earth ore has a natural proportion

La-Ce-Pr-Nd mixed rare earth is commercially available, wherein four elements of La, Ce, Pr, and Nd are main elements, and their molar ratio in the mixed rare earth is natural in the light rare earth ore. proportion. Preferably, the light rare earth mineral may include: a mineral such as bastnasite or monazite ore. Preferably, the impurity-containing La-Ce-Pr-Nd mixed rare earth has a purity of > 95 wt.%. The type of the impurity includes, but is not limited to, one or more of Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr, C, H, O. Kind. In some cases, the types of impurities in the La-Ce-Pr-Nd mixed rare earth include, but are not limited to, Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ti, Ca, Pb, Cr, One or more of C, H, and O.

Further, in the foregoing embodiment, the magnetic refrigeration material further contains one selected from the group consisting of Sm, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr, and O. Kind or multiple elements. In some cases, the magnetic refrigeration material further contains one or more elements selected from the group consisting of Sm, Mg, Zn, W, Mo, Cu, Ti, Ca, Pb, Cr, and O. The above elements are all introduced by the La-Ce-Pr-Nd mixed rare earth containing impurities. When the material to be prepared is composed only of La, Ce, Pr, Nd, Fe, Si, the chemical formula of the magnetic refrigeration material does not include carbon (C) and/or hydrogen (H) elements, and then is contained by impurities. The C and/or H element introduced by the La-Ce-Pr-Nd mixed rare earth also becomes an impurity at this time, and in this case, the magnetic refrigeration material further contains Sm, Mg, Zn, W, Mo, Cu, One or more elements of Ni, Ti, Th, Y, Ca, Pb, Cr, C, H, and O. In a second embodiment of the invention, the industrially pure mixed rare earth is a naturally proportioned LaCe alloy, such as a commercial industrial pure LaCe alloy, which is extracted from light rare earth ore as a rare earth purified intermediate. Preferably, the impurity-containing LaCe alloy has a purity of > 95 at%, preferably 95-98 at.% (wherein the &% represents atomic percentage). The La:Ce atomic ratio in the LaCe alloy is a natural ratio in the light olefinite ore, preferably 1: 1.6-1:2.3. The impurity species in the LaCe alloy may include, but are not limited to, Pr, Nd, Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr, C, H. One or more of O. In some cases, the impurity species in the LaCe alloy may include, but is not limited to, one of Pr, Nd, Fe, Si, Cu, Ni, Zn, Th, Y, Mg, Ca, C, H, O. Or a variety.

 Further, in the above second embodiment, the magnetic material further contains a selected from the group consisting of Pr,

One or more of Nd, Sm, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr and O. In some cases, the magnetic material further contains one or more elements selected from the group consisting of Pr, Nd, Cu, Ni, Zn, Th, Y, Mg, Ca, and O. These elements are introduced from the impurity-containing LaCe alloy. When the material to be prepared consists only of La, Ce, Fe, Si, since the bismuth is prepared by using the LaCe alloy containing impurities, the impurities present in the alloy are inevitably introduced together, then the four elements of Pr, Nd, C and H are in this case. The alloy also becomes an impurity, and the impurities contained in the magnetic material are Pr, Nd, C, H, Sm, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb. One or more of Cr, O and O.

It should be particularly noted that the impurity-containing LaCe alloy may be directly extracted from the rare earth ore, or may be obtained by processing the impurity-containing La-Ce-Pr-Nd mixed rare earth by processing Pr and Nd elements. La and Ce are the main constituent elements of the LaCe alloy. The La-Ce-Pr-Nd is mixed with rare earth ore. However, as long as the purity satisfies the above definition, the change in the type of impurities does not affect the implementation of the present invention and the magnetic refrigeration effect of the material. Therefore, the inventive concept of the present invention mainly utilizes an industrial pure mixed rare earth having a natural proportion as a raw material to prepare a La(Fe,Si) ₁₃ -based magnetic refrigeration material, which reduces dependence on high-purity elemental rare earth raw materials and reduces material preparation. Cost to promote its industrial production. In the present invention, Scheme 1) using an impurity-containing La-Ce-Pr-Nd mixed rare earth extracted from a light rare earth ore; and Scheme 2) using an impurity-containing LaCe alloy is two exemplary embodiments of the present invention, Therefore both embodiments belong to the same inventive concept. The La-Ce-Pr-Nd mixed rare earth and LaCe alloy as raw materials are all mixed rare earths with natural proportions extracted from light rare earth ore, and the magnetic refrigerating material properties of NaZn ₁₃ structure prepared by different raw materials are used. Basically the same, the difference in molecular formula is due to the natural proportion of mixed rare earth materials The ratio of elements between La-Ce-Pr-Nd and La-Ce is uncertain (depending on the natural components of the ore), so the molecular formulas of the two different expressions belong to the same inventive concept.

 In certain embodiments of the invention, the alpha may range from: 0 a 0.8.

 Further, according to the magnetic refrigeration material provided by the present invention, the magnetic refrigerating material may have a magnetic entropy change value of 5.0-50.0 J/kgK under a 0-5 Τ magnetic field change, and a phase change temperature zone of 10-400K.

 In another aspect, the present invention provides a method of preparing the above magnetic refrigeration material, the method comprising the steps of:

1) formulating raw materials according to chemical formula, when the hydrazine in the chemical formula includes hydrogen element, preparing raw materials other than hydrogen according to a chemical formula, the raw material includes industrial pure mixed rare earth, and the industrial pure mixed rare earth is used as a rare earth purified intermediate product from light rare earth ore. Extracted La-Ce-Pr-Nd mixed rare earth with natural proportion or impurity-containing LaCe alloy with natural proportion extracted from light rare earth ore, when the industrial pure mixed rare earth is extracted from light rare earth ore When the rare earth-containing La-Ce-Pr-Nd is mixed with rare earth, the chemical formula of the material is: La _1-x (Ce, Pr, Nd) _x (Fe^ _q Co _p Mn _q ) _13-y Si _y A _a , when the industrial pure mixed rare earth is a rare earth-containing LaCe alloy containing impurities in a rare earth ore purification process, the chemical formula of the material is:

 2) preparing an alloy ingot by using an arc smelting technique, placing the prepared raw material in step 1) into an electric arc furnace, vacuuming, cleaning with argon gas, and smelting under argon gas to obtain an alloy ingot;

或 La_1-x(Ce,Pr,Nd)_x(Fe_1-p-qCo_pMnq)_13-ySiyA_a磁热效应材料； 3) vacuum annealing the alloy ingot smelted in step 2), and then quenching in liquid nitrogen or water to obtain a structure having NaZn ₁₃

Or La _1-x (Ce,Pr,Nd) _x (Fe _1-p- qCo _p Mnq) _13- ySiyA _a magnetocaloric effect material;

 Wherein, when A in the above chemical formula includes a hydrogen element, the method further comprises the step 4): dividing the material obtained in the step 3) into a powder and annealing in hydrogen.

 According to the preparation method provided by the present invention, in one embodiment, the La, Ce, Pr and Nd elements in the raw material are La-Ce-Pr-Nd mixed rare earth having a natural proportion of impurities extracted from light rare earth ore. provide. In another embodiment, the La and Ce elements in the feedstock are provided by an impurity-containing LaCe alloy having a natural proportion extracted from the light rare earth ore. Preferably, the La element deficiency provided by the LaCe alloy or the La-Ce-Pr-Nd mixed rare earth is partially supplemented by the elemental La. The other elements in the chemical formula select a substance containing the element as a raw material according to a conventional method in the art, such that the ratio of the ratio of the amount of all elements and each elemental substance in the raw material to the amount of all elements and each elemental substance in the chemical formula the same.

Further, according to the aforementioned production method, in the raw material, when A includes the C element, the C element is preferably provided by the FeC alloy. Because element C has a high melting point, it is difficult to melt into the alloy. In addition, a FeC alloy made of elemental Fe and C can be used to ensure that a sufficient amount of C element can be introduced. At this time, since the Fe element also contains Fe element, it is necessary to appropriately reduce the added elemental Fe, so that the ratio of the added various elements still satisfies the atomic ratio in the chemical formula of the magnetic refrigeration material. Similarly, when A includes the B element, it is also preferable to provide the B element from the FeB alloy.

 Further, according to the aforementioned preparation method, other materials other than La-Ce-Pr-Nd mixed rare earth and/or LaCe alloy in the raw material, such as La, Fe, FeC, FeB, Co, Mn, Si, Pr,

Both Nd and B have a purity greater than 98 wt.%.

Further, according to the foregoing preparation method, the step 2) may include: placing the raw materials prepared in the step 1) into an electric arc furnace, evacuating to a vacuum degree of less than lx lO ² Pa, and using a purity greater than 99 wt.%. High-purity argon gas is used to clean the furnace chamber 1-2 times. Then, the furnace chamber is filled with the argon gas to 0.5-1.5 atmospheres, and the arc is arc-started to obtain alloy ingots. Each alloy ingot is repeatedly smelted at 1500-2500 °C. -6 times. Among them, the melting temperature is preferably 1800-2500 °C.

Further, according to the foregoing preparation method, the step 3) may include: annealing the alloy ingot smelted in the step 2) at 1000-1400 ° C and having a vacuum of less than 1 X 10" ³ Pa, and annealing for 1 hour. After 60 days, it is then quenched in liquid nitrogen or water to prepare a main phase of NaZn ₁₃ structure.

La _1-xz Ce _x R _z (Fe _1-p- qCo _p Mnq) _13- ySiyA _a or La _1-x (Ce,Pr,Nd) _x (Fe _1-p- qCOpMnq) _13- ySiyA _a

According to the foregoing preparation method, the step 4) may include: dividing the material obtained in the step 3) into a powder and annealing in hydrogen to obtain

Or _a hydride of La _1-x (Ce, Pr, Nd) _x (FenqCo _p Mnq) _13- ySiyA _a . Preferably, the amount of material entering the hydrogen in the alloy is controlled by adjusting the hydrogen pressure, the annealing temperature and the time.

Further, according to the foregoing preparation method, the step 4) may include: dividing the material prepared in the step 3) into an irregular powder having a particle diameter of less than 2 mm, placing a purity greater than 99 wt.%, and a pressure of 0. -100 atmospheres of hydrogen, the pressure of hydrogen is preferably 10 - ^{4 -} 100 atmospheres, annealing at 0-600 ° C for 1 min to 10 days, annealing preferably at 100 to 350 ° C for 1 minute to 3 days, thereby preparing Lai zCexR Fe^qCOpMnq^-ySiyAa or

La _1-x (Ce, Pr, Nd) _x (Fe _1-p- qCo _p Mnq) hydride of _13- ySiyA _a .

In still another aspect, the present invention provides a magnetic refrigerator, wherein the magnetic refrigerant used in the magnetic refrigerator includes the La (Fe, Si) ₁₃ -based magnetic refrigeration material provided by the present invention or is produced according to the method provided by the present invention. Magnetic refrigeration material.

In still another aspect, the present invention provides the use of the magnetic refrigeration material or the magnetic refrigeration material produced by the method provided by the present invention in the manufacture of a composite refrigeration material. The advantages of the present invention over the prior art are:

(1) The present invention utilizes an intermediate product of a rare earth purification process, a rare-phase La-Ce-Pr-Nd mixed rare earth or a light rare earth mineral containing impurities extracted from a light rare earth mineral such as bastnasite ore and monazite ore. The extracted LaCe alloy with natural proportion containing impurities as a raw material to prepare 1 ^ ^ _{13 13} -based magnetic refrigeration material reduces the dependence on high-purity elemental rare earth raw materials, reduces the preparation cost of materials, and develops magnetic materials for materials. Refrigeration applications have important practical implications;

 2) Since La is non-magnetic, one or more substitutions of magnetic Ce, Pr, Nd are introduced, La, exchange coupling (RR) between the same/different rare earth ions, and exchange coupling between rare earth ions and Fe ( RT) will give the compound a large saturation magnetic moment, resulting in a large magnetocaloric effect. Further, it has been found that the simultaneous introduction of Ce, Pr, Nd (i.e., the LaFeSi magnetic refrigeration material prepared by using La-Ce-Pr-Nd mixed rare earth as a raw material in the present invention) is more than that of Ce alone (i.e., the LaCe alloy is used as a raw material in the present invention). LaFeSi magnetic refrigeration material) can obtain a larger magnetocaloric effect at room temperature;

3) In the La(Fe,Si) ₁₃ -based magnetic refrigeration material prepared by the present invention, the impurities introduced from the raw material La-Ce-Pr-Nd mixed rare earth or LaCe alloy do not affect the formation of NaZn ₁₃ phase and the first-order phase transition. The appearance of features and variable magnetic transition behaviors maintains a huge magnetocaloric effect. This is completely different from the case of the famous giant magnetocaloric material Gd ₅ Si ₂ Ge ₂ , the presence and introduction of impurities in the Gd ₅ Si ₂ Ge ₂ alloy (eg C, H, 0, Fe, Co, Ni, Cu, Ga). , Al, etc.) will cause the first-order phase transition characteristics to disappear, and the giant magnetocaloric effect will disappear (J. Magn. Magn. Mater. 167, L 179 (1997); J. Appl. Phys. 85,

5365(1999) )o The best way to implement the invention

 The present invention will be further described below in conjunction with the embodiments. It should be noted that the following examples are for illustrative purposes only and are not intended to limit the invention. Various changes made by those skilled in the art in light of the teachings of the present invention are intended to be included within the scope of the appended claims.

 A description of the materials and equipment used in the examples is as follows:

1) The commercial LaCe alloy is a natural proportion of La-Ce alloy extracted from the world's largest light rare earth mineral-fluorocarbon antimony ore in Inner Mongolia, China. It is purchased from Inner Mongolia Baotou Steel Rare Earth International Trading Co., Ltd. There are two kinds of purity: (a) The purity of the LaCe alloy used in the embodiment 1-2 is 97.03 at.%, the atomic ratio of La and Ce is 1:1.88, and the impurity and content are: 0.05 at. ⁰ /. Pr, 0.05 at.% Nd, 0.71 at.% Fe, 0.24 at.% Si, 0.11 at.% Cu, 0.05 at.% Ni, 0.002 at.% Th, 0.63 at.% Zn, 1.14 at.% of O; (b) The LaCe alloy used in Examples 3-8 has a purity of 95.91 at.%, an atomic ratio of La and Ce of 1:2.24, and an impurity content of 0.07. At.% Pr, 0.07 at.% Nd, 0.92 at.% Fe, 0.35 at.% Si, 0.27 at.% Cu, 0.13 at.% Ni, 0.003 at.% Th, 0.91 at .% of Zn, 1.37 at.% of 0.

2) Industrial pure La-Ce-Pr-Nd mixed rare earth, which is a natural proportion of La-Ce-Pr-Nd mixed rare earth extracted from the world's largest light rare earth ore-fluorocarbon antimony ore in Inner Mongolia, China. Purchased from Inner Mongolia Baotou Steel Rare Earth International Trading Co., Ltd., there are two kinds of purity: The purity of the mixed rare earth used in Example 9-11 is 99.6 wt.%, and the contents of La, Ce, Pr and Nd are respectively: 28.27 \¥1. % of La, 50.46 wt. ⁰ /(^ Ce, 5.22 wt. of ⁰ / ₀ Pr, 15.66 wt.% of Nd, impurity and content of <0.05 wt. ⁰ /. Sm, 0.037 wt. ⁰ /. Fe, 0.016 wt. ⁰ /. of Si, 0.057 wt. ⁰ /. of Mg, <0.010 wt.% of Zn, 0.01 wt. ^o / (^ W, 0.007 wt. ⁰ /. Mo, <0·01 Wt.% Cu, <0.01 wt.% Ti, <0.01 wt.% Ca, <0.01 wt.% Pb, <0.03 wt.% Cr, <0.01 wt.% C; Example 12- The purity of industrial pure La-Ce-Pr-Nd mixed rare earth used in 15 is 98.4 wt.%, and the contents of La, Ce, Pr and Nd are respectively: 25.37 \¥1.% of La, 52.90 \¥1.% Ce, 4.57 wt.% Pr, 15.56 wt.% Nd.

 3) Other raw materials and their purity are: elemental La (purity 99.52 wt%), elemental Pr (98.97 wt.%), elemental Nd (98.9 wt.%), purchased from Hunan Shenghua Rare Earth Metal Materials Co., Ltd.; Fe ( 99.9 wt%) purchased from Beijing Nonferrous Metals Research Institute; FeC (99.9 wt%, Fe, C weight ratio: 95.76:4.24), smelted from elemental C and 99.9% by weight of Fe; Si (99.91 wt%) , purchased from Beijing Nonferrous Metal Research Institute; FeB alloy (99.9 wt.%, Fe, B weight ratio of 77.6:22.4), purchased from Beijing Zhongke Sanhuan High Technology Co., Ltd.; Co (99.97 wt%), purchased from Beijing Institute of Nonferrous Metals; Mn (99.8 wt.%), purchased from Beijing Shuanghuan Chemical Reagent Factory.

 The above raw materials are all in the form of blocks.

4) The electric arc furnace used is produced by Beijing Shike Optoelectronic Technology Co., Ltd. Model: WK-II non-consumable vacuum arc furnace, Cu target X-ray diffractometer is produced by Rigaku, model RINT2400, superconducting quantum interference vibration sample magnetic Strong meter (MPMS (SQUID) VSM), manufactured by Quantum Design (USA), model MPMS (SQUID) VSM. Example 1: Preparation of L _{an 7} C _en F _{ei 1} 6Si _{1 4} C _Y ( y = 0.2 and 0.3 ) Two kinds of magnetic refrigeration materials

( y=0.2和 0.3 )化学式配料， 原料为含杂质 的 LaCe合金 (纯度 97.03 at.%)、 以及 Fe、 Si、 La和 FeC, 其中， 单质 La 用来补充 LaCe合金中 La不足的部分， FeC合金用来提供 C , 由于 FeC合 金中也含有 Fe元素， 需要适当减少添加的单质 Fe , 使得添加的各种元素 的配比仍旧满足磁性材料化学式的原子配比； 2)将步骤 1) 中的原料混合， 放入电弧炉中， 抽真空至 2xlO_³Pa, 用 纯度为 99.996wt%的高纯氩气清洗炉腔 2次， 之后炉腔内充入纯度为 99.996wt%高纯氩气至一个大气压， 电弧起弧（电弧起弧后原材料就熔在 一起成为合金了， 下同） ， 获得合金锭， 每个合金锭子反复熔炼 4次， 熔 炼温度为 2000°C, 熔炼结束后， 在铜坩锅中冷却获得铸态合金锭； 1) Press

(y=0.2 and 0.3) chemical formula, the raw material is an impurity-containing LaCe alloy (purity: 97.03 at.%), and Fe, Si, La and FeC, wherein elemental La is used to supplement the La-deficient portion of the LaCe alloy, FeC The alloy is used to provide C. Since the FeC alloy also contains Fe element, it is necessary to appropriately reduce the added elemental Fe, so that the ratio of the added elements still satisfies the atomic ratio of the chemical formula of the magnetic material; Mixed raw material 2) in step 1), into an electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.996wt% of the high purity argon purged twice with cavity purity, after charging the cavity with a purity of 99.996 Wt% high purity argon gas to one atmosphere, arc arcing (the raw materials are melted together into an alloy after arc arcing, the same below), the alloy ingot is obtained, and each alloy spindle is repeatedly smelted 4 times, the melting temperature is 2000 °C After the smelting is finished, cooling in a copper crucible to obtain an as-cast alloy ingot;

3) The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a high vacuum (lxlO_ ⁴ Pa) quartz tube, annealed at 1080 ° C for 30 days, breaking the quartz tube liquid nitrogen quenching, La having a NaZn ₁₃ type structure was obtained. . ₇ Ce. ₃ Fe„. ₆ Si _L4 C _y (y=0.2, 0.3) sample.

 Performance Testing:

(y=0.2, 0.3 ) 两个样 品均为干净的 NaZn₁₃型单相结构， 这类体系尤其是掺 C体系中最容易出 现的 α-Fe杂相在这 2个样品中均没有出现， 表明 LaCe合金原材料中杂质 的存在并没有影响 NaZn₁₃相的形成和长大。 1. The room temperature X-ray diffraction (XRD) pattern of the sample was measured by Cu target X-ray diffractometer. As shown in Fig. 1, the results showed

(y=0.2, 0.3) Both samples are clean NaZn ₁₃ type single-phase structure, and the most probable α-Fe heterophase in this system, especially in the C-doped system, does not appear in these two samples, indicating The presence of impurities in the LaCe alloy raw material does not affect the formation and growth of the NaZn ₁₃ phase.

2. Determination on the superconducting quantum interference vibration sample magnetometer

(y=0.2, 0.3) The thermomagnetic (M-T) curve of the sample at 0.02 T magnetic field, as shown in Fig. 2, it can be seen that the temperature hysteresis is small, increasing with the C content from y=0.2 to y=0.3. The Curie temperature T _c rises from 200K to 212K.

 The magnetization curve (MH curve) of the rising process of Lao.7Ceo.3Fen.6Sii.4Cy ( y=0.2, 0.3 ) at different temperatures was measured on MPMS (SQUID) VSM. The graph shows the significant inflection point on the MH curve. The presence of magnetic field-induced magnetic transition behavior from paramagnetic to ferromagnetic states indicates that the presence of impurities in the LaCe alloy raw material does not affect the formation of the 1:13 phase, nor does it affect the appearance of the magnetic transformation behavior. The large magnetocaloric effect of the material.

According to Maxwell's relationship: MT, HS (H - S(T = ^H <^^ _H dH , magnetic entropy change AS can be calculated from isothermal magnetization curve. Figure 4 shows Lao.7Ceo.3Fen.6Sii.4Cy (y=0.2, 0.3) The dependence of AS on temperature in different magnetic fields. It can be seen that the peak shape of AS expands asymmetrically to the high temperature region with the increase of the magnetic field. The peak is followed by a platform, which is the first phase of La(Fe,Si) ₁₃ base. The typical characteristics of the variable system are derived from the magnetic field induced magnetic transition behavior above the Curie temperature. The AS peak shape further validates the existence of the first-order phase transition characteristics and the magnetic transformation behavior of the system, further indicating the presence of impurities in the LaCe alloy raw materials. Does not affect the formation of the 1:13 phase, does not affect the appearance of the magnetic transformation behavior, and guarantees the large magnetocaloric effect of the material. It has been shown that the appearance of the AS spike is due to the coexistence of two phases of the first-order phase transition process. There is no illusion of thermal effect, AS platform reflects the nature of magnetocaloric effect. y=0.2, 0.3 sample, 0-5T magnetic field change AS platform is 28.7J/kgK, 25.1J/kgK, respectively, which are significantly higher than traditional room temperature magnetic Magnetic entropy change of cooling material Gd (5T Under magnetic field, the magnetic entropy becomes 9.8J/kgK), the full width at half maximum is 19.4K, 20.4Κ, and the cooling capacity is 508.8J/kg and 462.8J/kg, respectively. The high and wide magnetic entropy change platform is especially needed for Ericsson type magnetic refrigeration machines, and is of great significance for practical magnetic refrigeration applications.

Conclusion: This example can be confirmed that the industrial pure LaCe alloy is used as raw material. According to the preparation process, La(Fe,Si) ₁₃ -based carbide with NaZn ₁₃ crystal structure can be prepared, and the impurities in the LaCe alloy raw material are present. Without affecting the formation and growth of the NaZn ₁₃ phase, the magnetic transformation behavior is still significant, showing a giant magnetocaloric effect, and the Curie temperature shifts to a high temperature as the C content increases.

Refrigerating material

1) Press La. . ₇ Ce. ₃ (Fe _1-x Co _x ) _1L6 Si _L4 (χ=0·04, 0.06 and 0.08) Chemical formula, raw material is impurity-containing LaCe alloy (purity 97.03 at.%), and Fe, Co, Si, La , wherein the elemental La is used to supplement the insufficient portion of La in the LaCe alloy;

Mixed raw material 2) in step 1), into an electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.996wt% high purity Ar gas purge cavity twice with a purity of, after the cavity is filled with a purity

99.996wt% high purity argon gas to one atmosphere, arc arcing, obtain alloy ingots, each alloy spindle is repeatedly smelted 4 times, the melting temperature is 2000 ° C, after melting, in the copper crucible to obtain

(χ=0·04, 0.06, 0.08) 样品。 3) The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a high vacuum (lxlO_ ⁴ Pa) quartz tube, annealed at 1080 ° C for 30 days, breaking the quartz tube liquid nitrogen quenching, Obtaining a structure with NaZn ₁₃ type

(χ=0·04, 0.06, 0.08) Sample.

 Performance Testing:

(x=0.04, 0.06,1. The room temperature X-ray diffraction (XRD) pattern of the sample was measured by Cu target X-ray diffractometer. As shown in Fig. 5, the results showed

(x=0.04, 0.06,

0.08) The main phases of the three samples are all NaZn ₁₃ type structures. The most prone a-Fe heterophase in this type of system does not appear in these three samples, and a small amount of unknown heterogeneous phase appears (marked with * in Figure 5). Whether or not the peak is related to the presence of impurities in the raw material LaCe alloy remains to be confirmed. These small amounts of unknown heterogeneous phase coexist with the NaZn ₁₃ type main phase, but the presence of the heterophase does not affect the formation and growth of the NaZn ₁₃ type main phase.

2. The thermomagnetic (Μ-Τ) curve of the sample of LaojCeoU oJu.sSiw (χ=0·04, 0.06, 0.08) in a magnetic field of 0.02 测定 is measured on a superconducting quantum interference vibration sample magnetometer MPMS (SQUID) VSM. As shown in Figure 6. It can be seen that the temperature lag is small, and the Co content increases from x=0.04 to x=0.08. The Curie temperature T _c rises from 222K to 280K.

( x=0.04, 0.06, 0.08 ) 在不同磁场下 AS对温度的依赖关系。 可以看出， AS峰形随着磁场 的增加向高温区不对称展开， 来源于居里温度以上磁场诱导的从顺磁至铁 磁态的变磁转变行为， 验证了体系的变磁转变行为的存在。 随着 Co含量 的增加， 变磁转变行为减弱， AS峰形逐步趋向对称。 AS峰形随磁场的不 对称展宽进一步表明 LaCe合金原材料中杂质的存在不影响 1 : 13相的生 成， 也不影响变磁转变行为的出现， 保证了材料的大磁热效应。 x=0.04, 0.06, 0.08三个样品， 0-5T磁场变化下 AS峰值分别为 25.1J/kgK、 18.2 J/kgK、 14.1 J/kgK, 位于 222K、 255Κ、 277Κ, 均高于传统室温磁制冷材料 Gd的 磁熵变 （5T磁场下， 磁熵变为 9.8J/kgK ) , 半高宽分别是 20.6K、 23.8Κ、 30.8Κ, 制冷能力分别是 448.8J/kg、 350.8J/kg、 340.3J/kg。 La ₀ . ₇ Ce ₀ . ₃ (Fe _1-x Co _x ) _1L6 Si _L 4 was measured on the MPMS (SQUID) VSM (χ=0·04, The magnetization curve (MH curve) of the 0.06, 0.08) sample at different temperatures is shown in Figures 7a-c. The presence of an inflection point on the MH curve (or an inflection point or a negative slope of the Arrott diagram (Fig. 7d) indicates the presence of a magnetic field induced magnetic transition from paramagnetic to ferromagnetic, indicating that the presence of impurities in the LaCe alloy raw material does not affect 1:13 phase. The generation does not affect the appearance of the magnetic transformation behavior, which ensures the large magnetocaloric effect of the material. At the same time, as the Co content increases, the magnetic transition behavior decreases and the inflection point disappears. According to the Maxwell relationship: AS(T,H)=S(T,H)-S(T,0)= ^j . 9τ ^{, Η} , The magnetic entropy change AS can be calculated from the isothermal magnetization curve. Figure 8 shows

(x=0.04, 0.06, 0.08) The dependence of AS on temperature under different magnetic fields. It can be seen that the AS peak shape asymmetry unfolds to the high temperature region with the increase of the magnetic field, and the magnetic field transition behavior from the paramagnetic to the ferromagnetic state induced by the magnetic field above the Curie temperature is verified, and the magnetic transformation behavior of the system is verified. presence. As the Co content increases, the magnetic transition behavior decreases, and the AS peak shape gradually becomes symmetrical. The asymmetric broadening of the AS peak shape with the magnetic field further indicates that the presence of impurities in the LaCe alloy raw material does not affect the formation of the 1:13 phase, nor does it affect the appearance of the magnetic transformation behavior, ensuring the large magnetocaloric effect of the material. Three samples of x=0.04, 0.06, 0.08, the peak values of AS under the 0-5T magnetic field change were 25.1J/kgK, 18.2 J/kgK, 14.1 J/kgK, respectively, at 222K, 255Κ, 277Κ, both higher than the traditional room temperature magnetic refrigeration. The magnetic entropy of the material Gd (magnetic entropy becomes 9.8J/kgK under 5T magnetic field), the full width at half maximum is 20.6K, 23.8Κ, 30.8Κ, and the cooling capacity is 448.8J/kg, 350.8J/kg, 340.3 respectively. J/kg.

Conclusion: This example can be confirmed that the industrial pure LaCe alloy is used as raw material. According to the preparation process, a La(Fe,Si) ₁₃ -based compound with a NaZn ₁₃ type crystal structure can be prepared. Co can replace Fe to increase the Curie temperature. Near to room temperature. The presence of impurities in the LaCe alloy raw material does not affect the formation and growth of the NaZn ₁₃ phase, and the system exhibits a giant magnetocaloric effect.

( y=0.1和 0.5 ) 化学式配料， 原料为含 杂质的 LaCe合金 (纯度 95.91at.%)、 以及 Fe、 Co、 Si、 La、 Pr, 其中， 单质 La用来补充 LaCe合金中 La不足的部分； 1) Press

(y=0.1 and 0.5) chemical formula, the raw material is an impurity-containing LaCe alloy (purity: 95.91 at.%), and Fe, Co, Si, La, Pr, wherein elemental La is used to supplement the La-deficient portion of the LaCe alloy. ;

Mixed raw material 2) in step 1), into an electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.996wt% of the high purity argon purged twice with cavity purity, after charging the cavity with a purity of 99.996 Gt% high purity argon to one atmosphere, arc arcing, to obtain alloy ingots, each alloy spindle is repeatedly smelted 6 times, the melting temperature is 1800 °C, 1900 °C, 2000 °C, 2100 °C, 2300 °C 2500 ° C, after the smelting is finished, cooling in a copper crucible to obtain an as-cast alloy ingot;

(y=0.1, 0.5) 样品。 3) The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a high vacuum (9xlO_ ⁴ Pa) quartz tube, and annealed at 1100 ° C for 50 days to break the quartz tube liquid nitrogen quenching. Obtained Has a NaZn ₁₃ type structure

(y=0.1, 0.5) sample.

 Performance tests were performed in the same manner as in Examples 1 and 2:

1. X-ray diffraction (XRD) pattern is shown in Fig. 9. The results show that both samples of the present example are crystallized into a NaZn ₁₃ type structure, and a small amount of heterophase observed is indicated by an * in Fig. 9.

 2. Figure 10 shows the thermomagnetic (M-T) curve measured at 0.02T magnetic field. It can be seen that

The Pr content increases from y=0.1 to y=0.5, and the Curie temperature T _c decreases from 187K to 177K. The temperature hysteresis increased from about 3 为 to about 5 Κ, indicating that the first-order phase transition property is enhanced. Fig. 11 is a graph showing the dependence of the magnetic entropy change AS on the temperature of the two samples of the present embodiment under a magnetic field change of 0 to 5 Torr. The effective magnetic entropy change (platform) under 0-5T magnetic field change is 22.7J/kgK (y=0.1) and 26.0J/kgK (y=0.5), respectively, and the effective magnetic entropy change is enhanced with the increase of Pr content.

Conclusion: This example can be confirmed that the industrial pure LaCe alloy is used as raw material. According to the preparation process, La(Fe,Si) ₁₃ -based compound with NaZn ₁₃ type crystal structure can be prepared. The presence of impurities in LaCe alloy raw materials is not Affecting the formation and growth of NaZn ₁₃ phase, with the substitution of rare earth Ce and Pr for La, the Curie temperature shifts to low temperature, the first-order phase transition property is enhanced, and the effective magnetic entropy is increased. Example 4: Preparation of 1 ^ ^^ ₄ ^„ (0=0, 0.2 and 0.4) three kinds of magnetic refrigeration materials

=0、 0.2和 0.4 )化学式配料， 原料为 La、 工业纯 LaCe合金 (纯度 95.91 at.%)、 以及 Fe、 Si和 FeB, 单质 La用于 补充 LaCe合金中 La不足的部分。 FeB合金用来提供 B, 由于 FeB合金中也 含有 Fe元素， 需要适当减少添加的单质 Fe, 使得添加的各种元素的配比仍 旧满足磁性材料化学式的原子配比。 1) Press separately

=0, 0.2 and 0.4) chemical formula, the raw material is La, industrial pure LaCe alloy (purity 95.91 at.%), and Fe, Si and FeB, and the elemental La is used to supplement the La-deficient part of the LaCe alloy. The FeB alloy is used to provide B. Since the FeB alloy also contains Fe element, it is necessary to appropriately reduce the added elemental Fe, so that the ratio of the added elements still satisfies the atomic ratio of the chemical formula of the magnetic material.

2) step 1) mixing raw materials, into the electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.996wt% of the high purity argon purged twice with cavity purity, after charging the cavity with a purity of 99.996wt % high purity argon to 1.5 atmospheres, arc arcing, to obtain alloy ingots, each alloy spindle is repeatedly smelted 6 times, the first 3 times of melting temperature is 1800 ° C, the last 3 times of melting temperature is 2000 ° C, after smelting , cooling in a copper crucible to obtain an as-cast alloy ingot.

3) Pack the as-cast alloy ingots prepared in step 2) with molybdenum foil and seal them under high vacuum ( 1 X 10- ⁴

Pa) Quartz tube, annealed at 1030 ° C for 60 days, break the quartz tube ice water quenching, get three

The La sCe sFe^Si Ba alloys are 0, 0.2 and 0.4, respectively.

 Performance tests were performed in the same manner as in Examples 1 and 2:

1. Room temperature X-ray diffraction (XRD) pattern (Fig. 12) shows that the three alloys of this example are crystallized into a NaZn ₁₃ type structure, and a small amount of α-Fe and other heterophases can be detected, marked with an *.

2. Figure 13 shows the thermomagnetic (MT) curve of the sample obtained in step (3) under a magnetic field of 0.02 T. It can be seen that the phase transition temperature is 183 Κ (α = 0), 187 Κ (α = 0.2), and 195 Κ (α = 0.4). According to the Maxwell relationship, the magnetic entropy change of the sample under the 0-1T magnetic field change is 24.8J/kgK. (α=0), 23.9J/kgK (α=0.2) and 11.6J/kgK (α=0.4) (Fig. 14).

Conclusion: This example can be confirmed that the industrial pure LaCe alloy is used as raw material. According to the preparation process, La(Fe,Si) ₁₃ -based borides with NaZn ₁₃ crystal structure can be prepared, and the impurities in the LaCe alloy raw materials are present. Without affecting the formation and growth of the NaZn ₁₃ phase, the system exhibits a giant magnetocaloric effect, and the Curie temperature moves toward a high temperature as the B content increases. Example 5: Preparation of two magnetic refrigeration materials of La^Ce^iFe^Co^Mn^^S^ (v=0.9 and 1.8)

1) Press La. ₉ Ce _i (Fe.. ₆ Co.. ₂ Mn.. ₂ ) _13-y Si _y ( y = 0.9 and 1.8 ) Chemical formula, the raw material is industrial pure LaCe alloy (purity 95.91at.%), and Fe, Si, Co, Mn, La, wherein the elemental La is used to supplement the La-deficient portion of the LaCe alloy.

2) step 1) mixing raw materials, into the electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.6% argon purged twice with cavity purity, after charging the cavity with a purity of 99.6% to an argon At 0.6 atm, the arc is arc-started, and an alloy ingot is obtained. Each alloy spindle is repeatedly smelted 5 times, and the melting temperature is 2400 ° C. After the smelting is completed, the as-cast alloy ingot is obtained by cooling in a crucible.

( y=0.9, 1.8 )二种 组分的合金。 3) The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a quartz tube, vacuum on the back: lxlO_ ⁴ Pa, high-purity argon (99.996wt%) to 0.2 at room temperature Atmospheric pressure (the purpose is to balance the external pressure after the temperature reaches the quartz softening temperature, the quartz tube is not deformed), then annealed at 1300 ° C for 3 days, the furnace is cooled to 1100 ° C, and the quartz tube liquid nitrogen quenching is removed from the furnace. Obtaining a structure with NaZn ₁₃ type

( y = 0.9, 1.8 ) an alloy of two components.

 Performance tests were performed in the same manner as in Examples 1 and 2:

1. The room temperature X-ray diffraction (XRD) pattern of the alloy of this example (Fig. 15) indicates that the main phase structure is a NaZn ₁₃ type structure, and a small amount of α-Fe and an unknown impurity phase (marked as a heterogeneous phase by *) are present.

( y=0.9和 1.8 )合金在Second, Figure 16 shows

(y=0.9 and 1.8) alloys in

Thermomagnetic (MT) curve at 0.02 T magnetic field. It can be seen that the phase transition temperatures are located at 97K and 70K, respectively. According to the Maxwell relationship, the entropy change under the change of 0-5 Τ magnetic field is 1.6 J/kgK and 2.5 J/kgK _{0 respectively.}

Conclusion: In combination with the foregoing examples and the present examples, it can be confirmed that the industrial pure LaCe alloy is used as the raw material, according to the preparation process, in the larger component range (Co content 0 ≤ p ≤ 0.2, Mn content 0 ≤ q ≤ 0.2, Si) The La(Fe,Si) ₁₃ -based magnetocaloric effect material with NaZn ₁₃ type crystal structure can be prepared in the content of 0.8≤y≤2.

Two magnetic refrigeration materials 1) Press Lao.7Ceo.3Fei LsSi Co. ₂ and Lao.7Ceo.3Fei LsSi Co. ₂ B, respectively. . . . 5 chemical formula, the raw material is industrial pure LaCe alloy (purity 95.91 at.%), and FeC, FeB, Si, La, wherein the elemental La is used to supplement the insufficient portion of La in the mixed rare earth.

2) step 1) mixing raw materials, into the electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.996wt% high purity Ar gas purge cavity once with a purity, after charging the cavity with a purity of 99.996wt % High-purity argon gas to one atmosphere, arc arcing, alloy ingots are obtained, and each alloy spindle is repeatedly smelted twice, and the melting temperature is 2000 ° C. After the melting is completed, the as-cast alloy ingot is obtained by cooling in a copper crucible.

3) The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a high vacuum ( 1 X 10- ⁴ Pa ) quartz tube, and annealed at 1080 ° C for 30 days to break the quartz tube liquid nitrogen. Quenching

Lao Ceo Fe! LsSiLsCcs and La. . ₇ Ce. . ₃ Fe _1L5 Si _L5 C. . ₂ B. . . . ₅ two alloys.

 4) The Lao.7Ce 3Fen.5Sii.5C 2 and Lao.7Ceo.3Fen.5SiL5C 2Bo.05 alloys obtained in the step 3) are respectively divided into alloy particles, and the particle size ranges from 0.05 to 2 mm.

5) Using the PCT tester to anneal the alloy particles obtained in step 4) in hydrogen: a. Place the LaojCei Fen.sSi^Ci alloy particles obtained in step 4) into the high pressure sample chamber of the PCT tester, and evacuate. To lxlO^ Pa, the sample chamber temperature is raised to 350 ° C, then high purity H ₂ (purity: 99.99%) is introduced into the sample chamber, and the H ₂ pressure is adjusted to 0.101, 0.205, 0.318, 0.411, 0.523, respectively. 0.617, 0.824, l.OHMPa, and maintain hydrogen absorption for 1 minute under each pressure, then place the high pressure sample chamber container in room temperature (20 ° C) water, cool to room temperature, according to the calculation, determine the H content is about 0.45 , obtained La 7Ceo.3Fen.5SiL5Co.2H. . ₄₅

b. Place the Lao.7Ceo.3Fen.5SiL5Co.2Bo.05 alloy particles obtained in step 4) into the high pressure sample chamber of the PCT tester, evacuate to lxlO^Pa, and raise the temperature of the sample chamber to 200 °C. High purity 3⁄4 (purity: 99.99%) was introduced into the sample chamber, and the pressure was adjusted to 0.0125, 0.0543, 0.115, 0.168, 0.218, 0.274, 0.326, 0.419 MPa, respectively. Under the first seven hydrogen pressures, hydrogen absorption was performed. Minutes, kept at the last hydrogen pressure for 3 days, then place the high pressure sample chamber container in water at room temperature (20 ° C), cool to room temperature, and determine the H content to be about 0.55 according to PCT analysis and weighing calculation. 1^. . ₇ 6. .^6 ₁₁ .^ ₁ . ₅ 0 ₎ . ₂ 8. . . . ₅ 3⁄4. ₅₅ hydride magnetic refrigeration material.

 Performance tests were performed in the same manner as in Examples 1 and 2:

1. The room temperature X-ray diffraction (XRD) pattern of the two hydride materials of this example shows that both hydride materials are NaZn ₁₃ type structures.

2. Figures 17a, b and 18a, b show the thermomagnetic (MT) curves of the two materials at 0.02 T magnetic field and the dependence of the magnetic entropy change (AS) calculated according to the Maxwell relationship on the temperature (calculated liter Field AS). Found La 7Ceo.3Feu.5SiL5Co.2H. ₄₅ and La 7Ceo.3Feu.5SiL5Ca2B o5Ho.55 The phase transition temperatures of the two hydride materials are ~ 248K and ~ 259K respectively; the maximum value of magnetic entropy change ( AS ) under 0-5T magnetic field change is about 19.3 J/kgK and 18.1J/kgK, the magnetocaloric effect is considerable. Conclusion: The multi-gap carbon/boron/hydrogen compound obtained by annealing 1^(?6,81) ₁₃ -based carbide/carbo boron compound prepared from industrial pure LaCe alloy under hydrogen atmosphere exhibits considerable magnetocaloric effect. The regulation hydrogen absorption process can adjust the phase transition temperature of the material to move to high temperature, so that the material has a large magnetic entropy change at high temperature, which is of great significance for practical magnetic refrigeration applications. Example 7: Preparation of La^Cen iEi^s^^i^Fe^S^ Magnetic Refrigeration Material

 1) According to La^Ce ^Pr Ndo.^ wFeu.sSi" chemical formula, the raw materials are industrial pure LaCe alloy (95.91at.%), and Fe, Si, La, Pr, and Nd.

Mixed raw material 2) in step 1), into an electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.996wt.% Of the high purity argon purged twice with cavity purity, after the cavity is filled with a purity

99.996wt.% of high-purity argon gas to one atmosphere, arc arcing, to obtain alloy ingots, each alloy spindle is repeatedly smelted 4 times, the melting temperature is 2000 °C, and after cooling, the as-cast alloy ingot is obtained;

3) The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a high vacuum (l xlO_ ⁴ Pa) quartz tube, annealed at 1080 ° C for 30 days, breaking the quartz tube liquid nitrogen quenching A sample of Lao Ceo^Pro^Nd osFe SiM having a NaZn ₁₃ structure was obtained.

 Performance tests were performed in the same manner as in Examples 1 and 2:

A sample at room temperature X-ray diffraction (XRD) pattern shown in Figure 19, the results show that _{Lao. 7 Ceo.2i (Pro.25Ndo. 75} ) o.o9Fe 11. 6 Si 1. 4 Sample main phase NaZn ₁₃ Type structure, there is a small amount of unknown impurity phase (marked with * in Figure 19).

2. The thermomagnetic (MT) curve of the sample under a magnetic field of 0.02 T is shown in Fig. 20. It can be seen that the Curie temperature T _{c of the} sample is 170 K, and the temperature lag Δ Τ is about 8 K. The magnetization curve (ΜΗ curve) of the up-field process at different temperatures was measured, and the magnetic entropy change AS calculated according to the Maxwell relationship is shown in Fig. 21. We found that the effective magnetic entropy change (AS platform) of the sample under 0-5T magnetic field change is 29.8J/kgK, and the full width at half maximum is 14.8K. The high and wide magnetic entropy change platform is especially needed for Ericsson type magnetic refrigeration machines, and is of great significance for practical magnetic refrigeration applications.

Conclusion: This example can be confirmed that the industrial pure LaCe alloy is used as raw material. According to the preparation process, La(Fe,Si) ₁₃ -based carbide with NaZn ₁₃ crystal structure can be prepared, and the impurities in the LaCe alloy raw material are present. It does not affect the formation and growth of NaZn ₁₃ phase. The simultaneous introduction of Ce, Pr, Nd to replace La can increase the hysteresis, indicating that the first-order phase transition property is enhanced and the effective magnetic entropy change is also enhanced. Example 8: Preparation of La^C^gg^g L^j^magnetic refrigeration material

 1) According to La^Cec Feu.sSiMQ chemical formula, the raw material is industrial pure LaCe alloy

(95.91at.%), and La, FeC, Fe, Si.

2) step 1) mixing raw materials, into the electric arc furnace, evacuated to 2xlO_ ³ Pa, pure The chamber was cleaned twice with 99.996 wt% high-purity argon gas. The furnace chamber was filled with high-purity argon with a purity of 99.996 wt% to 1.4 atm. The arc was arc-started to obtain alloy ingots. Each alloy spindle was repeated. The mixture was smelted twice, and the melting temperature was 2000 ° C. After the smelting was completed, the as-cast alloy ingot was obtained by cooling in a copper crucible.

3) The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a high vacuum (1 X 10- ⁴ Pa) quartz tube, and annealed at 1100 ° C for 10 days to break the quartz tube liquid nitrogen. Quenching

LaojCeojFen.sSiwQ alloy material.

4) The 1^ prepared in step 3). . ₇ 6. ₃ ?6 ₁₁ . ₍ ^ ₁ . ₄ 0 ₎ . _{1 The} alloy material is broken into irregular particles, and the average particle size range is 20~200 microns.

5) Using the PCT tester to anneal the La^Cec Fe^SiMC i alloy particles obtained in step 4) in hydrogen: Place the La^Cec Feu.sSiMQ irregular alloy particles into the high pressure sample chamber of the PCT tester. Vacuum the sample to lxlO^Pa, raise the temperature of the sample chamber to 120 °C, then pass the high purity 3⁄4 (purity: 99.99%) into the sample chamber, and adjust the pressure of 3⁄4 to 1χ10_ ⁵ , 2χ10 ^-3 , 0.1015, 1.579 , 2.083, 3.054, 4.128, 5.142, 6.190, 7.083, 8.120, 9.653 MPa (1 atm 0.101325 MPa), maintain hydrogen absorption time for 25 minutes under the first 11 hydrogen pressures, and maintain hydrogen absorption time at the last hydrogen pressure After 3 days, the high pressure sample chamber container was placed in water at room temperature (20 ° C), cooled to room temperature, and the H content was determined to be 2.9 according to PCT analysis and weighing calculation; thereby obtaining LaojCec Feu.sSiMQ H^ hydride magnetic Refrigerated material.

 Performance tests were performed in the same manner as in Examples 1 and 2:

1. The room temperature X-ray diffraction (XRD) pattern is shown in Fig. 22. The main phase is NaZn ₁₃ type structure, a small amount of heterophase exists, and the impurity phase is marked by *.

 2. Fig. 23 and Fig. 24 are the thermomagnetic (M-T) curves at 0.02 T magnetic field and the dependence of the magnetic entropy change (AS) calculated according to the Maxwell relationship on temperature (calculated ascension AS). We found that the phase transition temperature of LaojCec Fe^SiMQ H^ hydride material is ~ 348K, and the maximum magnetic entropy change is 22.8J/kgK under the variation of 0-5T magnetic field, and the magnetocaloric effect is considerable.

Conclusion: The multi-gap carbon/hydrogen compound obtained by annealing 1^(?6,81) ₁₃ -based carbide prepared from industrial pure LaCe alloy under hydrogen atmosphere exhibits considerable magnetocaloric effect and can be adjusted by regulating hydrogen absorption process. The amount of hydrogen absorption and the phase transition temperature move toward high temperature, which makes the material have a large magnetic entropy change at high temperature, which is of great significance for practical magnetic refrigeration applications. Example 9: Preparation of La^iCe Ndy^Fe^Si C^ (v=0, 0.1 and 0.2) Three kinds of magnetic refrigeration materials

1) Press La separately. . ₇ (Ce, Pr, Nd). ₃ Fe _1L6 Si _L4 C _y (y=0, 0.1 and 0.2) chemical formula, the raw material is industrial pure La-Ce-Pr-Nd mixed rare earth (purity 99.6wt%), elemental Fe, elemental Si, Elemental La and FeC alloys, in which elemental La is used to supplement the La-deficient part of the mixed rare earth, FeC alloy is used to provide C, and since the FeC alloy also contains Fe element, it is necessary to appropriately reduce the added elemental Fe, so that various additions are made. The ratio of the elements still satisfies the atomic ratio in the chemical formula.

2) Mix the raw materials in step 1), put them into an electric arc furnace, evacuate to 2xlO_ ³ Pa, and clean the furnace cavity with high purity argon gas with a purity of 99.996 wt.%, then fill the cavity with purity.

99.996wt.% of high-purity argon gas to one atmosphere, arc arcing, to obtain alloy ingots, each alloy spindle is repeatedly smelted 4 times, the melting temperature is 2000 °C, and after cooling, the as-cast alloy ingot is obtained.

 3) Pack the as-cast alloy ingots prepared in step 2) with molybdenum foil and seal them in high vacuum.

( lxlO_ ⁴ Pa) Quartz tube, annealed at 1080 ° C for 30 days, breaking the quartz tube liquid nitrogen quenching, to obtain La with NaZn ₁₃ type structure. . ₇ (Ce, Pr, Nd). . ₃ Fe _1L6 Si _L 4Cy (y = 0, 0.1, 0.2 ) # product.

 Performance Testing:

(y=0, 0.1, 0.2) 样品均为干净的 NaZn₁₃型单相结构， 这类体系尤其是掺 C体系中最 容易出现的 α-Fe杂相没有出现， 表明高 Ce工业纯混合稀土 La-Ce-Pr-Nd 原料中杂质的存在并没有影响 NaZn₁₃相的形成和长大，出现的少量未知杂 相 （图 25中标注 *号峰）是否与原材料高 Ce混合稀土中杂质的存在有关 还有待进一步确认， 这些少量未知杂相与 NaZn₁₃型主相共存， 但是， 杂相 的存在并没有影响 NaZn₁₃型主相的生成和长大。 1. The room temperature X-ray diffraction (XRD) pattern of the sample was measured by Cu target X-ray diffractometer. As shown in Fig. 25, the results showed

(y=0, 0.1, 0.2) The samples are all clean NaZn ₁₃ type single-phase structure. This type of system, especially the most prone to the α-Fe hetero phase in the C-doped system, does not appear, indicating that the high Ce industrial pure mixed rare earth La -The presence of impurities in the Ce-Pr-Nd material does not affect the formation and growth of the NaZn ₁₃ phase, and the presence of a small amount of unknown heterophase (marked with a * peak in Figure 25) is related to the presence of impurities in the high Ce mixed rare earth. It remains to be further confirmed that these small amounts of unknown heterogeneous phase coexist with the NaZn ₁₃ type main phase, however, the presence of the heterophase does not affect the formation and growth of the NaZn ₁₃ type main phase.

2. Determine the Lao. ₇ (Ce, Pr, Nd)o. ₃ Fe _1L6 Si _L4 C _y ( y = 0, 0.1, 0.2 ) sample in 0.02 on the superconducting quantum interference vibration sample magnetometer MPMS (SQUID) VSM Thermal magnetic field under T magnetic field

(MT) curve, as shown in Fig. 26, it can be seen that as the content of C increases, the Curie temperature T _c rises from 169K (y = 0) to 200K (y = 0.2); Small, from 8K (y=0) to 4K (y=0.2).

( y=0, 0.1, 0.2) 样品在不同温度下升场过程的磁化曲线 （MH曲线） ， 示于图 27, MH曲线上显著拐点的出现表明磁场诱导的从顺磁至铁磁态变磁转变 行为的存在，表明高 Ce工业纯混合稀土 LaCrPrNd中杂质的存在并不影响 1:13相的生成， 同时也不影响变磁转变行为的出现， 保证了材料的大磁热 效应。 Measured on MPMS (SQUID) VSM

( y = 0, 0.1, 0.2) The magnetization curve (MH curve) of the sample at different temperatures during the field rise, as shown in Figure 27. The presence of a significant inflection point on the MH curve indicates a magnetic field induced magnetic change from paramagnetic to ferromagnetic. The existence of transformation behavior indicates that the presence of impurities in the high-Ce industrial pure mixed rare earth LaCrPrNd does not affect the formation of the 1:13 phase, and does not affect the appearance of the magnetic transformation behavior, which ensures the large magnetocaloric effect of the material.

 The magnetic entropy change AS is calculated from the isothermal magnetization curve according to the Maxwell relationship. Figure 28 shows

La ₀ . ₇ (Ce, Pr, Nd). ₃ Fe _1L6 Si _L 4Cy (y=0, 0.1, 0.2 ) The dependence of AS on temperature in different magnetic fields. It can be seen that the AS peak shape asymmetry develops toward the high temperature region with the increase of the magnetic field, and the peak is followed by a platform. , which is a typical feature of the 1^(?6,80 ₁₃ -based first-order phase change system, derived from Magnetic field induced magnetic field transition behavior above temperature. The ΔS peak shape further verified the existence of first-order phase transition characteristics and magnetic transformation behavior of the system, further indicating that the presence of impurities in the high-Ce industrial pure mixed rare earth LaCrPrNd does not affect the formation of 1:13 phase, nor does it affect the magnetic transformation. The appearance of behavior ensures the large magnetocaloric effect of the material. Studies have shown that the appearance of AS spikes is due to the coexistence of two phases in the first-order phase transition process, and there is no illusion of thermal effects. The AS platform following the reaction reflects the nature of the magnetocaloric effect. y=0, 0.1, 0.2 samples, the height of the AS platform under the change of 0-5T magnetic field is 31.6J/kgK, 30.2J/kgK, 26.6J/kgK, respectively, which are significantly higher than the magnetic entropy change of the traditional room temperature magnetic refrigeration material Gd ( Under 5T magnetic field, the magnetic entropy becomes 9.8J/kgK), the full width at half maximum is 14.4K, 16.6Κ, 18.9K, and the cooling capacity is 404.6J/kg, 467.9 J/kg, 461.7J/kg „ high. The wide magnetic entropy change platform is especially needed for Ericsson-type magnetic refrigeration machines, and is of great significance for practical magnetic refrigeration applications.

Conclusion: This example can be confirmed that high-Ce industrial pure mixed rare earth is used as raw material. According to the preparation process, La(Fe,Si) ₁₃ -based carbide with NaZn ₁₃ type crystal structure can be prepared, and high Ce industrial pure mixed rare earth can be prepared. The presence of impurities in the material does not affect the formation and growth of the NaZn ₁₃ phase. The magnetic transformation behavior is still significant, showing a giant magnetocaloric effect, and the Curie temperature shifts to a high temperature as the C content increases.

0.08 and 0.1) Five magnetic refrigeration materials

1) Chemically compounded according to La ₀ . ₇ (Ce,Pr,Nd) ₃ (Fe _1-x Co _x ) _{11 6} Si _L 4 ( χ=0·02, 0.04, 0.06, 0.08 and 0.1), the raw materials are industrial Pure La-Ce-Pr-Nd mixed rare earth (purity 99.6 wt%), and elemental Fe, elemental Co, elemental Si and elemental La, wherein elemental La is used to supplement the insufficient portion of La in the mixed rare earth.

Mixed raw material 2) in step 1), into an electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.996wt.% Of the high purity argon purged twice with cavity purity, after the cavity is filled with a purity 99.996wt.% high purity argon gas to one atmosphere, arc arcing, obtain alloy ingot, each alloy spindle is repeatedly smelted 4 times, the melting temperature is 2000 ° C, after melting, in the copper crucible to obtain

( χ=0·02 , 0.04, 0.06, 0.08, 0.1 ) 样品。 3) The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a high vacuum (l xlO_ ⁴ Pa) quartz tube, annealed at 1080 ° C for 30 days, breaking the quartz tube liquid nitrogen quenching , obtained with NaZn ₁₃ type structure

( χ=0·02 , 0.04, 0.06, 0.08, 0.1 ) Sample.

 Performance Testing:

( x=0.02, 0.04, 0.06, 0.08, 0.1 ) 样品主相均为 NaZn₁₃型结构， 这类体系中最容易 出现的 α-Fe杂相在这 5个 Co含量不同的样品中均没有出现， 出现的少量 未知杂相 （图 29中标注 *号峰 )是否与原料高 Ce混合稀土中杂质的存在 有关还有待进一步确认， 这些少量未知杂相与 NaZn₁₃型主相共存， 但是， 杂相的存在并没有影响 NaZn₁₃型主相的生成和长大。 1. The room temperature X-ray diffraction (XRD) pattern of the sample was measured by Cu target X-ray diffractometer, as shown in Fig. 29, and the results showed

( x=0.02, 0.04, 0.06, 0.08, 0.1 ) The main phase of the sample is NaZn ₁₃ type structure, the easiest of such systems The α-Fe heterogeneous phase did not appear in the five samples with different Co content, and the presence of a small amount of unknown heterophase (marked with a * peak in Figure 29) is related to the presence of impurities in the high-content Ce mixed rare earth. It was further confirmed that these small amounts of unknown hetero phases coexisted with the NaZn ₁₃ type main phase, but the presence of the heterophase did not affect the formation and growth of the NaZn ₁₃ type main phase.

 2. Determination of superconducting quantum interference vibration sample magnetometer MPMS (SQUID) VSM

Lao. ₇ (Ce,Pr,Nd)o. ₃ (Fei _-x Co _x )ii. ₆ Si _L4 ( x=0.02 , 0.04, 0.06, 0.08 , 0.1 ) Thermomagnetic (MT ) of a sample at 0.02 T magnetic field The curve is shown in Figure 30. It can be seen that as the Co content increases, the Curie temperature T _c rises from 198K (χ=0·02) to 306K (χ=0·1); the temperature hysteresis decreases rapidly, when the Co content increases from χ=0.02 By χ=0.06, the temperature lag ΔΤ is reduced from 4Κ to 0.

Measured on MPMS (SQUID) VSM

 (x=0.02, 0.04, 0.06, 0.08, 0.1) The magnetization curve of the sample at different temperatures during the field rise is shown in Figure 31. The presence of an inflection point on the MH curve (Fig. 7a, b, c, d, e) (or the inflection point or negative slope of the Arrott diagram (Fig. 3 If, g, h, i, j) indicates that the magnetic field is induced from paramagnetic to iron The existence of magnetic transition behavior indicates that the presence of impurities in the high-Ce industrial pure mixed rare earth La-Ce-Pr-Nd raw material does not affect the formation of 1:13 phase, and does not affect the occurrence of magnetic transformation behavior. The large magnetocaloric effect of the material. At the same time, as the Co content increases, the magnetic transition behavior decreases and the inflection point disappears.

 The magnetic entropy change AS is calculated from the isothermal magnetization curve according to the Maxwell relationship. Figure 32 shows

Lao. ₇ (Ce, Pr, Nd) o. ₃ (Fe _1-x Co _x ) _{1 L6} Si _L4 ( x = 0.02 , 0.04 , 0.06 , 0.08 , 0.1 ) AS dependence on temperature in different magnetic fields. It can be seen that the AS peak shape asymmetry broadens to the high temperature region with the increase of the magnetic field, and the magnetic field transition behavior from paramagnetic to ferromagnetic state induced by the magnetic field above the Curie temperature, which verifies the magnetic transformation behavior of the system. presence. As the Co content increases, the magnetic transition behavior decreases, and the AS peak shape gradually becomes symmetrical. The asymmetry broadening of the AS peak shape with the magnetic field further indicates that the presence of impurities in the high-Ce industrial pure mixed rare earth La-Ce-Pr-Nd raw material does not affect the formation of the 1:13 phase, nor does it affect the occurrence of the magnetic transformation behavior. The large magnetocaloric effect of the material. Five samples of x=0.02, 0.04, 0.06, 0.08, 0.1, the AS peaks at 0-5T magnetic field change were 29.6J/kgK, 24.3J/kgK, 22.5J/kgK, 16.0J/kgK, 12.4J/kgK, respectively. , located at 198K, 225K, 254Κ, 279Κ, 306Κ, both higher than the magnetic entropy change of the traditional room temperature magnetic refrigeration material Gd (magnetic entropy becomes 9.8J/kgK under 5T magnetic field), the full width at half maximum is 18.2K, 20.9Κ 22.5Κ, 29.3Κ, 37.7Κ, refrigeration capacity reached 491.6J/kg, 446.9 J/kg, 396.8J/kg, 363.9J/kg, 359.6J/kg, respectively

Compared with LaFeSi-based materials prepared from LaCe alloys, the second-phase phase-change LaFeSi-based materials prepared from La-Ce-Pr-Nd mixed rare earths exhibit greater magnetocaloric effects near room temperature: for example, La- Secondary phase change system prepared by using Ce-Pr-Nd mixed rare earth as raw material La ₀ . ₇ (Ce,Pr,Nd) ₀ . ₃ (Fe _1-x Co _x ) _1L6 Si _L4 , x=0.06, 0.08 sample magnetic entropy peak under 5T magnetic field is 22.5J/kgK (254K) , 16.0J/kgK (279K), refrigeration capacity is 396.8J/kg, 363.9J/k, respectively; and the similar component secondary phase transformation system La ₀ . ₇ Ceo. ₃ (Fei _-y) prepared from LaCe alloy Co _y ) ii. ₆ Si _L4 , y = 0.06, 0.08 has a magnetic entropy of 18.2 J/kg K (251 K) and 14.1 J/kg K (279 K) , and the cooling capacities are 350.8 J/kg and 340.3 J/kg, respectively. The magnetic entropy change is higher than the latter by 24% and 13% respectively, and the former of the refrigeration capacity is 13% and 7% higher than the latter, which is caused by the competition of multiple exchange couplings of RR and RT.

Conclusion: This example can be confirmed that high-Ce industrial pure mixed rare earth is used as raw material. According to the preparation process, La(Fe,Si) ₁₃ -based compound with NaZn ₁₃ type crystal structure can be prepared, and high Ce industrial pure mixed rare earth raw material can be prepared. The presence of impurities in the middle does not affect the formation and growth of the NaZn ₁₃ phase. Co instead of Fe raises the Curie temperature to around room temperature. Compared with materials prepared from LaCe alloys, it exhibits a larger magnetocaloric effect in the room temperature region. Example 11: Preparation of La Ce.P Nd^Fe^SiuH hydride magnetic refrigeration material

 1) According to the chemical formula of Lao. Ce i^Nc^i Fen.sSiM, the raw material is industrial pure La-Ce-Pr-Nd mixed rare earth (purity 99.6wt%), elemental Fe, elemental Si and elemental La, among which elemental La It is used to supplement the insufficient portion of La in the mixed rare earth.

Mixed raw material 2) in step 1), into an electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.996wt.% Of the high purity argon purged twice with cavity purity, after the cavity is filled with a purity

99.996wt.% of high-purity argon gas to one atmosphere, arc arcing, to obtain alloy ingots, each alloy spindle is repeatedly smelted 4 times, the melting temperature is 2000 °C, and after cooling, the as-cast alloy ingot is obtained.

3) The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a high vacuum (lxlO_ ⁴ Pa) quartz tube, annealed at 1080 ° C for 30 days, breaking the quartz tube liquid nitrogen quenching, A sample of Lao. Ce i^Nc^i Feu.sSiM having a NaZn ₁₃ type structure was obtained.

 4) The Lao. Ce i^Nd Feu.sSiM sample was pulverized and sieved to obtain irregular particles having a particle size of 0.5 to 2 mm.

 5) The Lao.Ce^Nd Feu.sSiM particles were placed in a high pressure sample chamber of the PCT tester by a PCT tester, and the Lao.Ce^Nd Feu.sSiM irregular particles were placed in a high pressure sample chamber, and evacuated to lxlO^. Pa, raise the temperature of the sample chamber to 250 ° C, then pass high purity 3⁄4 (purity: 99.99%) into the sample chamber, and adjust the pressure of 3⁄4 to 0.1081, 0.1847, 0.2463, 0.2909, 0.3407, 0.3938, 0.4450, 0.5492 0.5989 MPa (1 atmosphere pressure 0.101325 MPa), and maintain hydrogen absorption time under each pressure: 3-10 minutes, then place the high pressure sample chamber container in room temperature (20 ° C) water, cool to room temperature, according to PCT Analysis and weighing calculations were carried out to obtain a Lao. Ce ^ Nd Fen.sSiMH ^ hydride magnetic refrigeration material having an H content of about 1.6.

Performance Testing: First, measured by Cu target X-ray diffractometer

The room temperature X-ray diffraction (XRD) spectrum before and after hydrogen absorption, as shown in Figure 33, shows that the main phase of the Lao. Ce i^Nd Feu.sSiMH^ sample before and after hydrogen absorption is NaZn ₁₃ type structure, due to the gap H atom The introduction of the unit cell parameters was expanded from 11.452A before hydrogen absorption to 11.576A after hydrogen absorption. A small amount of unknown heterogeneous phase appeared before and after the hydrogen absorption of the sample (marked with a * peak in Figure 33). Whether the presence of these unknown heterophases is related to the presence of impurities in the high-content Ce mixed rare earth remains to be confirmed. These small unknown phases are The NaZn ₁₃ type main phase coexists, but the presence of the hetero phase does not affect the formation and growth of the NaZn ₁₃ type main phase.

The thermomagnetic (MT) curve of the 0.02T magnetic field before and after hydrogen absorption of the Lao. Ce ^Nd Fen.sSiMH^ sample was measured on a superconducting quantum interference vibration sample magnetometer MPMS (SQUID) VSM, as shown in Figure 34. . It can be seen that the sample Curie temperature T _c rises from 169 K before hydrogen absorption to 314 K after hydrogen absorption, and the temperature lag decreases from 8 K before hydrogen absorption to 2 K after hydrogen absorption.

 The magnetization curves (MH curves) of the rising and falling fields at different temperatures before and after hydrogen absorption of the Lao. Ce ^Nd Fen.sSiwHLs samples were measured on MPMS (SQUID) VSM, as shown in Fig. 35a, b, Fig. 35c. The curve of magnetic hysteresis loss with temperature before and after hydrogen absorption of the sample. It can be seen that the Curie temperature of the sample is greatly increased to room temperature after hydrogen absorption, and the temperature hysteresis and magnetic hysteresis are greatly reduced. The maximum magnetic hysteresis decreases from about 232 J/kg before hydrogen absorption to about 42 J/kg after hydrogen absorption. .

 The magnetic entropy change AS is calculated from the isothermal magnetization curve according to the Maxwell relationship. Figure 36 shows

La^Ce ^Nd Feu.sSiMH^ The dependence of AS on temperature obtained during the up-and-down process of different magnetic fields before and after hydrogen absorption. After hydrogen absorption, the Curie temperature rises to near room temperature, although the peak value of effective magnetic entropy (magnetic entropy change platform) decreases from 32.5 J/kgK before hydrogen absorption to 27.8 J/kgK after hydrogen absorption. The peaks of magnetic entropy before and after hydrogen are much higher than those of the traditional room temperature magnetic refrigeration material Gd (the magnetic entropy becomes 9.8 J/kgK under 5T magnetic field), and the effective cooling capacity after deducting the maximum magnetic hysteresis loss is from hydrogen absorption. The previous 152 J/kg rose to 378 J/kg after hydrogen absorption, rising by about 150%. Large magnetocaloric effects and strong cooling capacity near room temperature are important for practical magnetic refrigeration applications.

Conclusion: The hydride obtained by annealing La(Fe,Si) ₁₃ based compound prepared from high Ce industrial pure mixed rare earth in hydrogen atmosphere exhibits considerable magnetocaloric effect. The phase transition temperature of the material can be adjusted by regulating hydrogen absorption process. Moving to high temperature, hysteresis loss is reduced, effective cooling capacity is increased, and the material exhibits superior magnetocaloric effect at high temperature or even room temperature, which is important for practical magnetic refrigeration applications.

Example 12: Preparation of 1^^(^, ?1^, ^)" ^^ _{1 4} ^„ (0=0.1, 0.3, and 0.5) Three kinds of magnetic refrigeration materials 1) Press La separately. . ₈ (Ce, Pr, Nd). ₂ Fe ₁₁ .4Si ₁ . ₆ B _α =0·l, 0.3 and 0·5 ) Chemical formula, raw material is industrial pure La-Ce-Pr-Nd mixed rare earth (purity 98.4wt%), elemental La, elemental Fe , elemental Si and FeB alloy.

2) step 1) mixing raw materials, into the electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.996wt% of the high purity argon purged twice with cavity purity, after charging the cavity with a purity of 99.996wt % high purity argon gas to 1.4 atmospheres, arc arcing, alloy ingots, each alloy spindle is repeatedly smelted 4 times, the melting temperature is 1800 ° C, 2000 ° C, 2200 ° C, 2500 ° C, after the smelting , cooling in a copper crucible to obtain an as-cast alloy ingot.

3) The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a high vacuum (1 X 10- ⁴ Pa) quartz tube, and annealed at 1030 ° C for 60 days to break the quartz tube ice water. Quenching, obtaining La. . ₈ (Ce, P^Nd^ Fe^Si^Ba three alloy samples (α, 0.1, 0.3 and 0.5 respectively).

 Performance tests were performed in the same manner as in Examples 1 and 2:

1. The room temperature X-ray diffraction (XRD) pattern of the alloy material of this example (Fig. 37) shows that the alloy is crystallized into a NaZ _{ni 3} type structure, and a small amount of unknown heterophase such as α-Fe appears (marked with * peak in the figure). These small amounts of unknown heterogeneous phase coexist with the NaZn ₁₃ type main phase, and the presence of the heterophase does not affect the formation and growth of the NaZn ₁₃ type main phase.

 2. Figure 38 shows the thermomagnetic (MT) curve of the alloy material obtained in step (3) under a magnetic field of 0.02 T. It can be seen that the phase transition temperature is 183 Κ (α = 0.1 ) and 192 Κ ( α = 0.3 ), respectively. 206 Κ (α = 0.5). According to the Maxwell relationship, the magnetic entropy changes of the three alloy samples under the 0-1Τ magnetic field change are 23.5J/kgK (α=0.1), 12.0J/kgK (α=0.3) and 7.8J/kgK (α=0.5). (As shown in Figure 39).

Conclusion: This example can be confirmed that high-Ce industrial pure mixed rare earth is used as raw material. According to the preparation process, La(Fe,Si) ₁₃ -based boride with NaZn ₁₃ type crystal structure can be prepared, and high Ce industrial pure mixed rare earth can be prepared. The presence of impurities in the raw materials does not affect the formation and growth of the NaZn ₁₃ phase. The system exhibits a giant magnetocaloric effect, and the Curie temperature moves toward a high temperature as the B content increases.

 1) According to Laa C^P^Nd Fe^SiMCc chemical formula, the raw material is industrial pure

La-Ce-Pr-Nd mixed rare earth (purity 98.4% by weight), and La, FeC, Fe, Si.

2) step 1) mixing raw materials, into the electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.996wt% of the high purity argon purged twice with cavity purity, after charging the cavity with a purity of 99.996wt % of high purity argon to 1.4 atmospheres, arc arcing, obtaining alloy ingots, each alloy spindle is repeatedly melted After 6 times of smelting, the melting temperature was 2000 ° C. After the smelting was completed, the as-cast alloy ingot was obtained by cooling in a copper crucible. 3) The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a high vacuum (1 X 10- ⁴ Pa) quartz tube, and annealed at 1100 ° C for 10 days to break the quartz tube liquid nitrogen. Quenching, obtaining La. . ₇ (Ce, Pr, Nd^^Fen^SiL.Co.i alloy material.

4) The La ₇ (Ce, Pr, Nd) ₀ . ₃ Fe ₁₁ . ₆ Si ₁ . ₄ C ₀ .i alloy material prepared in the step 3) is broken into irregular particles, and the particle size ranges from 0.05 to 2 Glutinous rice.

5) La ₀₇ (Ce, Pr, obtained by step 4) using the PCT tester

The alloy particles are annealed in a hydrogen atmosphere: The Lao. Ce i^Nd Feu.sSiMQ irregular alloy particles are placed in the high pressure sample chamber of the PCT tester, evacuated to lxlO^Pa, and the sample chamber temperature is raised to 120°. C, then pass high purity 3⁄4 (purity: 99.99%) into the sample chamber, and adjust the 3⁄4 pressure to lxlO ^-5 , 2χ10 ^-3 , 0.1017, 1.505, 2.079, 3.013, 4.182, 5.121, 6.076, 7.102, 8.074 , 9.683MPa (1 atm 0.101325MPa), maintain hydrogen absorption time for 25 minutes under the first 11 hydrogen pressures, and maintain hydrogen absorption time for 3 days under the last hydrogen pressure, then place the high pressure sample chamber container at room temperature (20 °C) in water, cooled to room temperature, according to PCT analysis and weighing calculation, determine H content is about 2.8;

Lao^Ce i^Nd Fe^SiMQ H^ hydride magnetic refrigeration material.

 Performance tests were performed in the same manner as in Examples 1 and 2:

First, the room temperature X-ray diffraction (XRD) spectrum is shown in Figure 40. The main phase is NaZn ₁₃ type structure, which contains a small amount of heterophase, and the impurity phase is marked with *.

 2. Figure 41 and Figure 42 show the dependence of the thermomagnetic (M-T) curve at 0.02 T magnetic field and the magnetic entropy change (AS) calculated according to the Maxwell relationship (calculation of the up-field AS). We found that the phase transition temperature of the Lao^Ce i^Nd Fen.sSiMQ H^ hydride material is located.

The maximum magnetic entropy change of ~347K, 0-5Τ magnetic field is 23.6 J/kgK, and the magnetocaloric effect is considerable.

Conclusion: The multi-gap carbon/hydrogen compound obtained by annealing La(Fe,Si) ₁₃ -based carbide prepared by high-Ce industrial pure mixed rare earth as raw material exhibits considerable magnetocaloric effect and can be adjusted by regulating hydrogen absorption process. The amount of hydrogen absorption, the phase transition temperature shifts to high temperature, so that the material has a large magnetic entropy change at high temperature, which is of great significance for practical magnetic refrigeration applications. Example 14: flJil^ i ^ MkiiEgfl^fl^ aa ^iiJb^L ^I^ Two kinds of magnetic refrigeration materials

1) Press La separately. ₉ (Ce, Pr, Nd) oi (Feo.6Coo. ₂ Mno. ₂ ) _13-y Si _y ( y=0.9 and 1·8 ) Chemical formula, raw material is industrial pure La-Ce-Pr-Nd mixed rare earth (purity 98.4 wt%), and Fe, Si, Co, Mn, La.

2) step 1) mixing raw materials, into the electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.6% of the high purity argon purged twice with cavity purity, then charged into the oven cavity purity of 99.6% argon, The gas is heated to 0.6 atmospheres, the arc is arc-started, and the alloy ingot is obtained. Each alloy spindle is repeatedly smelted 5 times, and the melting temperature is 2400 ° C. After the melting is completed, the as-cast alloy ingot is obtained by cooling in a copper crucible.

3) The as-cast alloy ingots prepared in step 2) are separately wrapped with molybdenum foil, sealed in a quartz tube, vacuum on the back: lxlO_ ⁴ Pa, high-purity argon (99.996wt%) to 0.2 at room temperature Atmospheric pressure (the purpose is to balance the external pressure after the temperature reaches the quartz softening temperature, the quartz tube is not deformed), then annealed at 1380 ° C for two hours, the furnace is cooled to 1100 ° C, and the quartz tube liquid nitrogen quenching is removed from the furnace. An alloy of two components of La ₀₉ (Ce, Pr, Nd) _i (Fe ₀ . ₆ Co ₀ . ₂ Mn ₀ . ₂ ) _13-y Si _y (y=0.9 and 1.8) was obtained.

 Performance tests were performed in the same manner as in Examples 1 and 2:

First, the room temperature X-ray diffraction (XRD) pattern shows that the main phase structure of the two materials is NaZn ₁₃ type structure, and there are α-Fe and unknown heterophase. Figure 43 shows Ι^. . ₉ ε _ι (Ρε ₆ α). . ₂ Μη. ₂ ) A room temperature X-ray diffraction (XRD) pattern of ₁₃ ί _γ (y = 1.8) alloy particles, marked with * as a heterophase.

2. Figure 44 shows the La ₉ (Ce, Pr, Nd) _i (Fe ₀ . ₆ Co ₂ Mn ₀ . ₂ ) _13-y Si _y ( y = 0.9 and 1.8) alloy samples at 0.02 Τ magnetic field. Thermomagnetic (Μ-Τ) curve. It can be seen that the phase transition temperatures of the two materials are at 102K and 71K, respectively, and the entropy changes under the change of 0-5 Τ magnetic field are 1.4 J/kgK and 2.3 J/kgK, respectively.

Conclusion: With the combination of Example 10 and this example, it can be confirmed that the industrial pure La-Ce-Pr-Nd mixed rare earth is used as the raw material, according to the preparation process, in the larger component range (Co content 0 ≤ p ≤ 0.2, Mn A La(Fe,Si) ₁₃ -based magnetocaloric material with a main phase of NaZn ₁₃ structure can be prepared with a content of 0 ≤ q ≤ 0.2 and a Si content of 0.8 < y ≤ 1.8. Example 15: Preparation of La Ce Ndy^Fe^Si^G^B^H^ multi-gap magnetic refrigeration material

 1) According to La ^Ce i^Nd Fen SiLsQ^B chemical formula, the raw material is industrial pure La-Ce-Pr-Nd mixed rare earth (purity 98.4wt%), and FeC, FeB, Fe, Si, La.

2) step 1) mixing raw materials, into the electric arc furnace, evacuated to 2xlO_ ³ Pa, 99.996wt% high purity Ar gas purge cavity once with a purity, after charging the cavity with a purity of 99.996wt % High-purity argon gas to one atmosphere, arc arcing to obtain alloy ingots, each alloy spindle is repeatedly smelted twice, and the melting temperature is 2000 ° C. After the smelting is finished, the as-cast alloy ingot is obtained by cooling in a copper crucible.

3) The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a high vacuum (1 X 10- ⁴ Pa) quartz tube, and annealed at 1080 ° C for 30 days to break the quartz tube liquid nitrogen. Quenching and obtaining La. . ₇ (Ce, Pr, Nd). . ₃ Fe„. ₅ Si _L5 C.. ₂ B.. ₅ alloy.

4) La prepared in step 3). . ₇ (Ce, Pr, Nd). ₃ Fe ₁₁ . ₅ Si ₁ . ₅ C. . ₂ B . ₅ alloy is divided into alloy particles, particle size range: 0.05~2mm.

 5) Annealing the alloy particles obtained in step 4) in a hydrogen atmosphere using a PCT tester: placing the Lao^Ce^Nd Fen.sSiLsC sBo.M alloy particles obtained in step 4) into the high pressure sample chamber of the PCT tester Inside, evacuate to lxlO^Pa, raise the temperature of the sample chamber to 350 °C, then pass high purity 3⁄4 (purity: 99.99%) into the sample chamber, and adjust the pressure of 3⁄4 to 0.0113, 0.0508, 0.116, 0.164, respectively. 0.205, 0.262, 0.410, 0.608, 0.874 MPa (1 atm 0.101325 MPa), maintain hydrogen absorption time for 1 minute under the first eight hydrogen pressures, and hold for 3 days under the last hydrogen pressure, then place the high pressure sample chamber container At room temperature (20 ° C) in water, cooled to room temperature, according to PCT analysis and weighing calculation, determine H content is about 0.55, thus obtaining

Lao. Ce i^Nd Feu.sSiLsQ B osHo Hydride magnetic refrigeration material.

 Performance tests were performed in the same manner as in Examples 1 and 2:

1. Room temperature X-ray diffraction (XRD) pattern shows that the hydride material is NaZn ₁₃ type structure. 2. Figure 45 and Figure 46 show the dependence of the thermomagnetic (MT) curve at 0.02 T magnetic field and the magnetic entropy change (AS) calculated according to the Maxwell relationship (calculated ascension field AS). It is found that the phase transition temperature of Lao.^Ce i^Nd Feu.sSiLsCc B osH^ hydride material is respectively at -263K; the maximum value of magnetic entropy change (AS) under the change of 0-5T magnetic field is about 19.0J/kgK, and the magnetocaloric effect is considerable. .

Conclusion: The multi-gap carbon/boron/hydrogen compound obtained by annealing La(Fe,Si) ₁₃ -based carbon/boron compound prepared from industrial pure mixed rare earth La-Ce-Pr-Nd under hydrogen atmosphere is considerable. The magnetocaloric effect, by regulating the hydrogen absorption process, can adjust the phase transition temperature of the material to move to high temperature, so that the material has a large magnetic entropy change at high temperature, which is of great significance for practical magnetic refrigeration applications. Comparative Example: Rare earth metal Gd

A typical room temperature magnetic refrigeration material elemental rare earth Gd (purity 99.9 wt.%) was selected as a comparative example. The Curie temperature was 293K measured on the MPMS (SQUID) VSM, and the magnetic entropy at the Curie temperature became 9.8 J/kgK under a 0-5 5 magnetic field change. It is found that the magnetic entropy of La(Fe,Si) ₁₃ -based magnetic refrigeration materials prepared by using industrial pure La-Ce-Pr-Nd mixed rare earth or industrial pure LaCe alloy as raw materials in most of the above examples greatly exceeds Gd, indicating that the material has a greater magnetocaloric effect.

 The present invention has been described in detail above with reference to the preferred embodiments thereof. It should be understood that the above detailed description should not be construed as limiting the scope of the invention. Therefore, various changes and modifications can be made to the embodiments of the invention without departing from the spirit and scope of the invention.

Claims

Patent claim 1. A 1^(?6, 80 ₁₃ -base magnetic refrigeration material prepared by using industrial pure mixed rare earth as a raw material, wherein the industrial pure mixed rare earth is extracted from a light rare earth mineral as a rare earth purified intermediate product and has a natural impurity Proportion of La-Ce-Pr-Nd mixed rare earth or LaCe alloy with natural proportions containing impurities extracted from light rare earth ore, the magnetic material having a NaZn ₁₃ type structure, When the industrial pure mixed rare earth is an impurity-containing La-Ce-Pr-Nd mixed rare earth extracted from a light rare earth ore, the chemical formula of the material is:

 Wherein A is selected from one or more of the elements C, H and B,  The range of X is: 0 < x 0.5, preferably 0 < x 0.3,  The range of p is: 0 p 0.2,  The range of q is: 0 q 0.2,  The range of y is: 0.8<y 1.8,  The range of α is: 0<α<3.0,  Wherein, the relative molar ratios of the three elements of Ce, Pr, and Nd are the natural proportions of Ce, Pr, and Nd in the La-Ce-Pr-Nd mixed rare earth, and the total number of moles thereof is X; In the Ce-Pr-Nd mixed rare earth, the molar ratio of the four elements of La, Ce, Pr and Nd is its natural proportion in the light rare earth ore, and the purity of the La-Ce-Pr-Nd mixed rare earth is > 95 wt. %, preferably purity > 98 wt.%, said The impurities in the La-Ce-Pr-Nd mixed rare earth include Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr, C, H, O One or more; When the industrial pure mixed rare earth is an impurity-containing LaCe alloy extracted from a light rare earth ore, the chemical formula of the material is:

 Wherein R is selected from one or both of Pr and Nd elements,  A is selected from one or more of C, H and B elements,  The range of X is: 0 < x 0.5, preferably 0 < x 0.3,  The range of z is: 0 z 0.5, and χ+ζ<1,  The range of p is: 0 p 0.2,  The range of q is: 0 q 0.2,  The range of y is: 0.8<y<1.8,  The range of α is: 0 α 3.0,  Wherein, the purity of the LaCe alloy is >95 at.%, and the La:Ce atomic ratio in the alloy is its natural proportion in the light rare earth ore, preferably 1:1.6-1:2.3, and impurities in the LaCe alloy include Pr , Nd, -32- Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr, C, One or more of H and O.  2. The magnetic refrigeration material according to claim 1, wherein, in the case where the industrial pure mixed rare earth is an impurity-containing La-Ce-Pr-Nd mixed rare earth, the magnetic refrigeration material further contains a selected from the group consisting of Sm One or more elements of Mg, Zn, W, Mo, Cu, Ti, Ca, Pb, Cr, O; when the chemical formula A does not include C and H elements, the magnetic refrigeration material It further contains one or more elements selected from the group consisting of Sm, Mg, Zn, W, Mo, Cu, Ti, Ca, Pb, Cr, C, H, and O.  The magnetic refrigerating material according to claim 1, wherein, in the case where the industrial pure mixed rare earth is an impurity-containing LaCe alloy: the magnetic refrigerating material further contains Pr, Nd, Cu, Ni, One or more elements of Zn, Th, Y, Mg, Ca, O; when the magnetic material is LaCeFeSi, further containing Pr, Nd, C, H, Cu, Ni, Zn, Th, Y, Mg One or more elements of Ca, O.  The method of producing a magnetic refrigeration material according to any one of claims 1 to 3, which comprises the steps of:  1) formulating a raw material according to a chemical formula, when A in the chemical formula includes a hydrogen element, preparing a raw material other than hydrogen according to a chemical formula, the raw material comprising an industrial pure mixed rare earth, the industrial pure mixed rare earth being used as a rare earth purification intermediate product from a light rare earth Mineral-derived impurities with a natural proportion La-Ce-Pr-Nd mixed rare earth or impurity-containing LaCe alloy with natural proportion extracted from light rare earth ore, when the industrial pure mixed rare earth is an impurity-containing La-Ce-Pr extracted from light rare earth ore -Nd When mixing rare earths, the chemical formula of the material is:

When the industrial pure mixed rare earth is an impurity-containing LaCe alloy extracted from a light rare earth ore during the rare earth purification process, the chemical formula of the material is:

 2) preparing an alloy ingot by using an arc smelting technique, placing the prepared raw material in step 1) into an electric arc furnace, vacuuming, cleaning with argon gas, and smelting under argon gas to obtain an alloy ingot; 3) vacuum annealing the alloy ingot smelted in step 2), and then quenching in liquid nitrogen or water to obtain La _1-xz Ce _x R _z (Fe _1-M Co _p Mnq) _13- ySiyA _a having a NaZn ₁₃ structure. or La _1-x (Ce,Pr,Nd) _x (Fe _1-pq Co _p Mn _q ) _13-y Si _y A _a magnetocaloric effect material;  Wherein, when A in the above chemical formula includes a hydrogen element, the method further comprises the step 4): dividing the material obtained in the step 3) into a powder and annealing in hydrogen.  5. The method according to claim 4, wherein in the raw material La-Ce-Pr-Nd mixed rare earth, the molar ratio of the four elements of La, Ce, Pr, Nd is its natural in the light rare earth ore a ratio of the La-Ce-Pr-Nd mixed rare earth having a purity of > 95 wt.%, preferably a purity of > 98 wt.%, - 33 - The impurities in the La-Ce-Pr-Nd mixed rare earth include Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr, C, H, O One or more.  The method according to claim 4, wherein the raw material LaCe alloy has a purity of > 95 at.%, and the La and Ce atomic ratio in the alloy is a natural proportion thereof in the light rare earth ore, preferably 1:1.6-1:2.3, impurities in the LaCe alloy include Pr, Nd, Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr, One or more of C, H, and O.  The preparation method according to any one of claims 4 to 6, wherein, in the raw material, when A includes a C element, a C element is provided by a FeC alloy; preferably, when A includes a B element, FeB alloy provides B element. The preparation method according to claim 4, wherein the step 2) comprises: placing the raw material prepared in the step 1) into an electric arc furnace, and vacuuming to a degree of vacuum of less than lx lO ² Pa, using a purity greater than 99 wt.% of argon gas is used to clean the furnace chamber 1-2 times. Then, the furnace chamber is filled with the argon gas to 0.5-1.5 atmospheres, and the arc is arc-started to obtain alloy ingots. Each alloy ingot is at 1500-2500 ° C. The melting is repeated 1-6 times, and the melting temperature is preferably 1800-2500 °C. 9. The preparation method according to claim 4, wherein the step 3) comprises: annealing the alloy ingot smelted in the step 2) at 1000-1400 ° C and having a vacuum of less than 1 X 10- ³ Pa. 1 hour to 60 days, then quenched in liquid nitrogen or water to prepare a main phase of NaZn ₁₃ structure La _1-xz Ce _x R _z (Fe _1-p- qCOpMnq) _13- ySiyA _a or La _1-x (Ce,Pr,Nd) _x (Fe _1-p- qCOpMnq) _13- ySiyA _a , The preparation method according to claim 4, wherein the step 4) comprises: dividing the material obtained in the step 3) into an irregular powder having a particle diameter of less than 2 mm, and placing the purity higher than 99 wt.%. In a hydrogen gas having a pressure of 0-100 atmospheres, the pressure of hydrogen gas is preferably 10 - ^{4 -} 100 atmospheres, and annealing is performed at 0-600 ° C for 1 minute to 10 days, preferably at 100-350 ° C for 1 minute to 3 hours. day.  A magnetic refrigerator comprising the magnetic cooling material according to any one of claims 1 to 3 or the magnetic refrigeration material produced by the method according to any one of claims 4 to 10.  Use of the magnetic refrigerating material according to any one of claims 1 to 3 or the magnetic refrigerating material produced by the method according to any one of claims 4 to 10 for producing a refrigerating material. - 34 -