CN100406536C - A novel rare-earth three-primary-color phosphor and its preparation method - Google Patents

Abstract

The invention discloses a rare-earth three-primary-color fluorescent powder, whose composition is represented by the following general formula: La ₂ O ₃ :xRE, wherein RE is rare-earth doped ion praseodymium Pr, neodymium Nd, europium Eu, terbium Tb, x=0.001～ 0.1. It also discloses a liquid-phase mixing-high-temperature solid-phase preparation method of the rare earth trichromatic fluorescent material. The rare-earth three-color phosphor can be excited by 250-300nm ultraviolet light to emit red, green and blue light respectively, especially the green light has the best effect. Moreover, La ₂ O ₃ :RE (RE=Pr, Eu, Tb, Nd) all have similar excitation spectra. Therefore, the trichromatic fluorescent powder that can be used as excimer discharge light source excitation of the present invention is used for developing new green energy-saving mercury-free fluorescent lamps or for RED fluorescent powder. The preparation method can fully disperse and contact the lanthanum oxide and the rare earth doping ions in the solution, and finally make the reactants mix more uniformly, and the composition distribution of the prepared fluorescent powder is more uniform, and can be obtained with finer particle size and better luminous effect. Phosphor.

Description

A novel rare-earth three-primary-color phosphor and its preparation method

technical field

The invention relates to an ultraviolet-excited luminescent material and a preparation method thereof, in particular to a novel rare-earth three-primary-color phosphor used for excimer light source excitation and RED display and a preparation method of the phosphor.

Background technique

Energy saving and environmental protection are the two major themes of green lighting. At present, the energy-saving lighting effect widely used is about 701m/w. The phosphor powder needs mercury vapor as the working gas, and mercury pollutes the environment. An important research direction of mercury-free fluorescent lamps. The excimer light source has its unique advantages, such as working under atmospheric pressure, because there is no self-absorption of radiation, the luminous efficiency is very high, up to 50% to 80%, and it has a very high power density (>1MW/cm ³ ), the duration of the micro-discharge channel is on the order of ns, the discharge can be started quickly, and various shapes of lighting lamps can also be made according to needs. Moreover, it emits a narrow-band spectrum, and its luminous wavelengths range from the visible to the vacuum ultraviolet region. It is considered to be a promising new generation of lighting sources. The key to the development of excimer discharge fluorescent lamps is to study the three primary color phosphors excited by the corresponding wavelengths (such as XeBr ^* , Br ₂ ² excimer discharge luminescence wavelengths are 282 and 289nm, respectively). On the other hand, RED flat panel display and its luminescent materials are also important targets of current research.

In terms of patent literature disclosure of luminescent materials, the early green fluorescent powder for lamps disclosed in Chinese Patent Publication No. CN1104235A uses related rare earth oxides and diammonium hydrogen phosphate as raw materials, and adds appropriate amount of active SiO ₂ , H ₃ BO ₃ and Li ₂ CO ₃ , through high-temperature solid-state reaction, to prepare a phosphor that emits green fluorescence under ultraviolet laser light. The chemical formula of this phosphor is: (La _1-XYZ Ce _X Tb _Y ) ₂ O ₃ ·(1-mn )P ₂ O ₅ ·zLiO·mSiO ₂ ·nB ₂ O ₃ .

Such as Chinese Patent Publication No. CN1146478A disclosed compound based on rare earth phosphate is used as a luminous body in the plasma system, said compound is a phosphate of general formula LnPO ₄ doped with at least one rare earth element, wherein Ln It is yttrium, lanthanum, gadolinium or lutetium, and its rare earth doping element is a mixture of terbium and cerium.

For example, the Chinese Patent Publication No. CN1190115A discloses a manufacturing method of a blue fluorescent powder, the chemical expression of which is BaMgAl14O23:Eu.

For example, Chinese Patent Publication No. CN1278855A discloses the use of thulium-containing lanthanum phosphate-based compounds as fluorescent materials in plasma or X-ray systems, which also contains gadolinium in lanthanum phosphate.

For example, the Chinese Patent Publication No. CN1276406 discloses a high-efficiency rare-earth phosphate green phosphor, and its chemical composition is: (Ln _1-XYZ Tb _X R _Y Li _Z )[(1-m)PO ₄ ·mBO ₃ ]. In the formula, Ln is Y, La, Gd and Lu; R is Ce, Pr, Dy rare earth elements.

For example, Chinese Patent Publication No. CN1408812A discloses a borate red fluorescent powder for color plasma flat panel display and its manufacturing method. The chemical formula of the fluorescent powder is (Y _1-XYZ Gd _Z M _Y Eu _X )BO ₃ , M One or more of La, Tb, Sm.

For example, the rare earth blue fluorescent material disclosed in Chinese Patent Publication No. CN1483788, its preparation method and application, the general formula of this kind of rare earth blue fluorescent material is: (M1) _x (M2) _y Eu _z (M3) _w (SiO ₃ ) _n Cl _m SiO ₂ , where M1 is an alkali metal element selected from sodium, potassium, rubidium or a combination thereof, M2 is an alkaline earth metal element selected from magnesium, calcium, strontium, barium or a combination thereof, and M3 is selected from yttrium , lanthanum, terbium, cerium or a combination of rare earth metal elements.

For example, Chinese Patent Publication No. CN1580183A discloses a rare earth-activated Y ₂ SiO ₅ phosphor and its preparation method and application. The phosphor is composed of yttrium oxide or yttrium nitrate, silicon dioxide, lanthanide oxide or nitrate , the lanthanide compound is cerium oxide, europium oxide or terbium oxide, and the nitrate is cerous nitrate, europium nitrate or terbium nitrate. The phosphor matrix is a high-temperature phase of Y ₂ SiO ₅ , and the phosphor is Y ₂ SiO ₅ :Tb, Y ₂ SiO ₅ :Ce, Tb, Y ₂ SiO ₅ :Ce or Y ₂ SiO ₅ :Eu.

In addition, in terms of foreign patent documents for luminescent materials, there are patents related to the production method of rare earth phosphate phosphors such as Japanese Patent Application No. 5-171143 (July 1993) and Japanese Patent Application No. 6-128565 (May 1994).

A novel yttrium oxide europium gadolinium red powder with the chemical formula (Y _1-ab Gd _a Eu _b ) ₂ O ₃ reported in USP6097146.

A new borate red powder with the chemical formula (Y _1-abC Gd _C M _b Eu _a )BO ₃ reported in US Patent No. 6,042,747.

U.S. Patent No. USP3897359 reports a kind of europium-excited alkali metal aluminosilicate fluorescent material and its preparation method. The chemical composition formula of the fluorescent material is (Ca _{x Sry} B _z Eu _p )O _x+y+z+p Al ₂ O ₃ ·2SiO ₂ , under the excitation of 200-380nm ultraviolet rays or electron beams, the wavelength range of its emission spectrum is from the near ultraviolet region to the blue-white region.

For the above-mentioned fluorescent materials, some are prepared by high-temperature solid phase reduction method.

For example, the green fluorescent powder for lamp disclosed in Chinese Patent Publication No. CN1104235A is to dissolve an appropriate amount of various rare earth oxides in nitric acid, then adjust the pH value, add oxalic acid to form oxalate co-precipitation, and then add H ₃ BO ₃ , active SiO ₂ and Li ₂ CO ₃ , burn at 600°C for 1-3 hours, then use 85% phosphoric acid to react with the burnt product, dry and burn at 1200-1400°C in a weak reducing atmosphere. The obtained product is heat-treated at 700-800°C for 10 minutes.

For example, the Chinese Patent Publication No. CN1146478A discloses that the rare earth phosphate-based compound is used as a luminescent body in a plasma system, and the precipitate is calcined at 900-1200° C. under a reducing atmosphere.

Another example is the use of thulium-containing lanthanum phosphate-based compounds as fluorescent materials in plasma or X-ray systems disclosed in Chinese Patent Publication No. CN1278855A, which also calcines phosphate at a temperature of at least 1000°C.

Another example is a kind of high-efficiency rare-earth phosphate green phosphor disclosed in Chinese Patent Publication No. CN1276406. Its preparation method is to weigh the corresponding rare-earth oxide and phosphate, lithium-containing salts, and borides. After pre-burning at 700-950°C for 0.5-3 hours, take it out and grind it evenly, and then burn it for the second time at 1050-1350°C for about 1-3 hours. This process is carried out in a weakly reducing atmosphere.

Another example is that the Chinese Patent Publication No. CN1408812A discloses a method for preparing borate red fluorescent powder for color plasma flat panel display, which is to weigh the required rare earth metal oxide according to the proportion of the chemical formula: lanthanum oxide (La ₂ O ₃ ), one or more of yttrium oxide (Y ₂ O ₃ ) _{, gadolinium oxide (Gd 2 O 3 ) and europium oxide (} Eu ₂ O ₃ ) is dissolved in nitric acid or hydrochloric acid to form a rare earth metal salt solution, and then under heating conditions, the prepared oxalic acid or carbonate solution is added to the rare earth metal salt solution to obtain the oxalate or carbonate of the rare earth metal salt deposits. After drying the oxalate or carbonate precipitates of rare earth metals, the mixture of rare earth metal oxides is obtained after keeping the temperature at 800-1200° C. for 0.5-2 hours. Finally, the mixture of rare earth metal oxides, boric acid, flux and agate balls are evenly mixed together, and then calcined at a temperature of 1100-1450° C. to obtain borate red powder.

Another example is that a new type of yttrium oxide europium gadolinium red powder with the chemical formula (Y _1-ab Gd _a Eu _b ) ₂ O ₃ reported in US Patent No. USP6097146 is also synthesized by a high-temperature solid-state reaction method, which first weighs Y ₂ O _3. Dissolve Gd ₂ O ₃ , Eu ₂ O ₃ in nitric acid, add oxalic acid solution to precipitate, decompose at 1000°C to obtain rare earth metal oxides, add co-solvent and mix well, and roast at 1400°C to obtain yttrium oxide europium gadolinium red powder.

The main disadvantages of using high-temperature solid-state reduction method to obtain rare earth fluorescent materials are high energy consumption and high cost. At the same time, it is easy to introduce impurities during the high-temperature sintering process to affect the chromaticity of the prepared fluorescent material, and it is difficult to further process the prepared fluorescent material to obtain fine-sized phosphor powder.

At present, a sol-gel method is also used to prepare rare earth fluorescent materials, such as a new type of borate red powder with the chemical formula (Y _1-abC Gd _C M _b Eu _a )BO ₃ reported in US Patent No. 6,042,747.

Also as Chinese patent publication number is CN1580183A disclosed a kind of rare earth activated Y ₂ SiO ₅ fluorescent powder, its preparation method is also like this, is to dissolve yttrium oxide and lanthanide rare earth compound in the hot concentrated nitric acid in heating and stirring equipment, react After completion, add silicone lipid compounds, adjust the pH value of the solution to 4-8, and let it stand for a period of time at a constant temperature of 60-100°C to form a gel; heat the gel at 300-600°C for a period of time to obtain a solid-phase product; After the phase product is ground, burn it in a reducing atmosphere in the range of 400-1000°C, grind it after burning, add one or more inorganic salts, burn it again in a reducing atmosphere in the range of 800-1600°C, and cool it. Take out and wash with dilute acid to obtain Y ₂ SiO ₅ phosphor activated by rare earth.

Another example is the preparation method of the rare earth blue fluorescent material disclosed by the Chinese Patent Publication No. CN1483788. It adopts two methods to prepare the sol, one is to mix the water-soluble alkali metal salt and excess hydrochloric acid evenly, and then mix Add a sufficient amount of alkyl orthosilicate to the solution, and stir until a uniform and transparent sol is formed. Another method is to stir the water-soluble alkali metal salt and excess hydrochloric acid evenly, then mix enough alkyl orthosilicate and hydrochloric acid, stir and hydrolyze, add the mixed solution of water-soluble alkali metal salt and excess hydrochloric acid, stir until a uniform transparent sol is formed. The pH value of the obtained transparent sol is less than 7, adding alkaline earth metal salts and rare earth metal salts therein, stirring and mixing evenly, adding excess reducing agent and stirring, and standing still to obtain wet gels. After the wet gel is dried, it is heat-treated at 500-800° C. in a non-oxidative atmosphere to obtain a rare-earth blue fluorescent material.

Although the preparation of rare earth blue fluorescent materials by the above sol-gel method can be carried out under mild conditions, the sintering temperature is greatly reduced, and high-purity fluorescent materials can be produced, which effectively avoids the problem of introducing impurities due to high sintering temperatures. , and each raw material component is mixed more uniformly, and the composition distribution of the prepared fluorescent material is more uniform. However, there are also problems that the operation is relatively complicated, the process is relatively long, the production cost is high, and the production efficiency is low.

Regarding rare earth trichromatic fluorescent materials, the early report has Dutch Philip JMPJVerstegen in American Electrochemical Society Journal (J.Electrochem.Soc) 1974 121 volume 12 period 1627 pages entitled "light effect is 80 lumens/watt , a new generation of luxury fluorescent lamps with a color rendering index of 85", this technology adopts the synthesis method of rare earth three-based toner, and synthesizes (Y ₁ Eu) ₂ O ₃ emitting red light and (Ce .Tb)MgAl ₁₁ O ₁₉ and blue-emitting (Ba ₁ Eu)Mg ₂ Al ₁₆ O ₂₇ , and then mix these three monochrome powders in a certain proportion to make certain required phosphors.

And Chinese Patent Publication No. CN1135513A discloses the preparation of single-base double-doped rare earth three-primary color fluorescent material, which is mixed with Eu ³⁺ and Tb ³⁺ in the alkaline earth metal oxo-salt and then sintered to obtain three kinds of fluorescent systems that emit coexistence .

Also, Chinese Patent Publication No. CN1311285A discloses a rare earth three-color fluorescent material for plant tissue culture, which is made by uniformly mixing yttrium oxide red powder, cerium magnesium aluminate green powder and barium magnesium aluminate blue powder, and The yttrium oxide red powder and the barium magnesium aluminate blue powder are respectively mixed with the activator europium, and the cerium magnesium aluminate green powder is mixed with the activator terbium. Or it is made by uniformly mixing vanadium yttrium phosphate red powder, yttrium oxide red powder, magnesium fluorogermanate red powder, barium magnesium aluminate blue powder, strontium pyrophosphate purple light powder and rare earth ultraviolet powder, and respectively in advance in vanadium yttrium phosphate red powder, Yttrium oxide red powder, magnesium fluorogermanate red powder, barium magnesium aluminate blue powder and strontium pyrophosphate purple powder are doped with activator europium, and magnesium fluorogermanate red powder is doped with activator manganese.

Furthermore, the preparation method of rare earth luminescent materials disclosed in Chinese Patent Publication No. CN1338501A is based on "a pair of rare earth ions with conjugated electronic configurations can realize electron transfer under certain conditions and produce abnormal changes in valence states". Theory, choose calcium borophosphate and its cerium (Ce) sensitization system co-doped with rare earth europium (Eu) and terbium (Tb), calcium boroaluminophosphate and its cerium (Ce) sensitization system, calcium oxychloride borate and its cerium sensitization system (Ce) sensitization system, and after the three are mixed and sintered, a rare earth trichromatic phosphor with three emission wavelengths coexisting is obtained.

Furthermore, the Chinese Patent Publication No. CN1603385A discloses an alkali metal tin phosphate-based luminescent material and a preparation method thereof. The chemical composition formula of the matrix is MSn ₃ P ₃ O _11+x . Where M is sodium and potassium, doped alkali metal tin phosphate luminescent material, its chemical composition formula is MSn ₃ P ₃ O _11+x : R, R is doped rare earth and manganese, gallium and other elements, doping amount 20% or less of the amount of tin substance.

Contents of the invention

An object of the present invention is to provide a rare earth trichromatic phosphor powder with good stability and good luminous intensity, which can be used as excimer discharge light source excitation and green energy-saving mercury-free fluorescent lamp or RED display.

Another object of the present invention is to provide a preparation method of the rare earth three-primary-color phosphor, which can further improve the uniformity and luminous effect of the obtained rare-earth three-primary phosphor.

The purpose of the present invention can be achieved through the following technical solutions.

The present invention provides a kind of rare earth trichromatic fluorescent powder, its composition is represented by the following general formula: La ₂ O ₃ :xRE, wherein RE is rare earth doped ion praseodymium Pr, neodymium Nd, europium Eu, terbium Tb, x=0.001～0.1 .

The present invention also provides a method for preparing rare earth three primary color phosphors, the method has the following steps:

1. Prepare the liquid phase by the following method:

Mix stoichiometric amounts of lanthanum oxide and rare earth nitrate solutions and grind them. When grinding, grind the solid particles as finely as possible until the solution presents a uniform slurry to obtain a liquid phase. The rare earths are praseodymium Pr, neodymium Nd, and europium Eu or terbium Tb;

2. After drying the liquid phase, grind again. After grinding, heat-treat the uniformly mixed sample at 800-1300°C for 2-4 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain rare earth tricolor phosphor.

In a preferred example of the present invention, the rare earth nitrate solution is selected from ethanol or aqueous solution of rare earth nitrate.

The rare earth trichromatic phosphor powder prepared by the present invention has the molecular formula La ₂ O ₃ :RE (RE=Pr, Nd, Eu, Tb). Lanthanum oxide is used as a matrix, and rare earth doped ions are used as a fluorescence activator. Since the rare earth ion radius and chemical properties are very close, the rare earth doped ions can well enter the lanthanum oxide lattice. In this system, rare earth doped ions are used as fluorescent activators, which can emit characteristic spectra of different colors. For example, the strong absorption band of La ₂ O ₃ :Pr is in the range of 250-300nm, and within this range of excitation light, it can generate strong 510nm green light (as shown in Figure 2). The excitation spectrum of La ₂ O ₃ : Nd has two substantially equal height peaks around 250 and 308nm, and similar broadband emission peaks are obtained when excited by these two wavelengths, and the strongest emission wavelength is blue light at 460nm (as shown in Figure 3 Show). The absorption spectra of La ₂ O ₃ :Eu and La ₂ O ₃ :Tb are similar to those of La ₂ O ₃ :Pr, the strong absorption bands are in the range of 250-300nm, and the characteristic emission peaks of Eu and Tb are excited, and their emission The peaks are all sharp-line spectra (respectively red light and green light), which are 4f-4f electronic transition emission of rare earth ions (as shown in Figures 4 and 5).

The liquid-phase mixing-high-temperature solid-phase method adopted in the present invention is characterized in that lanthanum oxide and rare earth doped ions are fully dispersed and contacted in the solution, then dried and ground, and finally the reactants are mixed more uniformly, and the obtained fluorescent The distribution of powder composition is more uniform, and phosphor powder with finer particle size and better luminous effect can be produced.

The rare-earth three-primary-color fluorescent powder of the invention can be excited by 250-300nm ultraviolet light, and emit red, green, and blue three-color light respectively, especially the best effect of green light. Moreover, La ₂ O ₃ :RE (RE=Pr, Eu, Tb, Nd) all have similar excitation spectra. Therefore, the trichromatic fluorescent powder that can be used as excimer discharge light source excitation of the present invention is used for developing new green energy-saving mercury-free fluorescent lamps or for RED fluorescent powder.

Description of drawings

Figure 1 is an XRD pattern _{of La2O3} :RE of an illustrative example of the present invention;

Fig _. 2 is the fluorescence spectrogram of _La2O3 :Pr of illustrative example of the present invention;

Fig. 3 is the fluorescence spectrogram of La ₂ O ₃ : Nd of illustrative example of the present invention;

Fig. 4 is the fluorescence spectrogram of La ₂ O ₃ :Eu of the illustrative example of the present invention;

Fig. 5 is the fluorescence spectrogram of La ₂ O ₃ : Tb of the illustrative example of the present invention;

Detailed ways

A rare-earth three-primary-color phosphor, whose composition is represented by the following general formula: La ₂ O ₃ :xRE, wherein RE is rare-earth doped ions of praseodymium Pr, neodymium Nd, europium Eu, terbium Tb, and the molar ratio x=0.001-0.1.

In the rare earth three-color phosphor powder of the present invention, lanthanum oxide is used as a matrix, and rare earth doped ions are used as a fluorescent activator. Since the rare earth ion radius and chemical properties are very close, the rare earth doped ions can well enter the lanthanum oxide crystal lattice In this way, the fluorescence performance of the phosphor powder can be well maintained.

The rare earth trichromatic phosphor powder of the present invention is prepared by the above-mentioned liquid phase mixing-high temperature solid phase method, so that the lanthanum oxide and the rare earth doping ions are fully dispersed and contacted in the solution, and finally the reactants are mixed more uniformly. The invention solves the problems of high energy consumption and high cost in obtaining the rare earth fluorescent material by the existing high-temperature solid phase reduction method. At the same time, it solves the problems that the sol-gel method is complicated to operate, the flow process is relatively long, the production cost is high, and the production efficiency is low.

In the preparation method of the present invention, the solvent used is ethanol or water, and the rare earth nitrate solution is selected from ethanol or aqueous solution of the rare earth nitrate. But not limited to this, as long as the selected solvent can dissolve the rare earth nitrate and will not adversely affect the luminescent performance of the obtained rare earth trichromatic phosphor, which is relatively easy for those skilled in the art to do.

In the preparation method of the present invention, the grinding time is well known to those skilled in the art, and is generally 5-10 minutes. In the method of the present invention, the temperature of the liquid-phase drying is also well known to those skilled in the art, and is generally 60-200° C., and the time is controlled as required. The high-temperature sintering is carried out under airtight conditions, and the airtight conditions are also well known to those skilled in the art.

The present invention is further illustrated by the following examples, but it should be understood that these examples are only exemplary, and the present invention is not limited thereto.

Example 1

Mix 1.629g La ₂ O ₃ and 5mL 0.01mol/L Pr(NO ₃ ) ₃ ethanol solution evenly, and grind for five minutes to grind the solid particles as finely as possible until the solution becomes a uniform slurry. Dry it, then grind it again, place the uniformly mixed sample in a muffle furnace, and treat it at 1200°C for 2 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain the product.

Example 2

Mix 1.629g La ₂ O ₃ and 5mL 0.01mol/L Nd(NO ₃ ) ₃ ethanol solution evenly, and grind for five minutes to grind the solid particles as finely as possible until the solution becomes a uniform slurry. Dry it, then grind it again, place the uniformly mixed sample in a muffle furnace, and treat it at 1200°C for 2 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain the product.

Example 3

Mix 1.629g La ₂ O ₃ and 5mL 0.01mol/L Eu(NO ₃ ) ₃ ethanol solution evenly, and grind for five minutes to grind the solid particles as finely as possible until the solution becomes a uniform slurry. Dry it, then grind it again, place the uniformly mixed sample in a muffle furnace, and treat it at 1200°C for 2 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain the product.

Example 4

Mix 1.629g La ₂ O ₃ and 5mL 0.01mol/L Tb(NO ₃ ) ₃ ethanol solution evenly, and grind for five minutes to grind the solid particles as finely as possible until the solution becomes a uniform slurry. Dry it, then grind it again, place the uniformly mixed sample in a muffle furnace, and treat it at 1200°C for 2 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain the product.

Example 5

Mix 1.629g La ₂ O ₃ and 5mL 0.01mol/L Pr(NO ₃ ) ₃ aqueous solution evenly, and grind for five minutes to grind the solid particles as finely as possible until the solution becomes a uniform slurry. Dry it, then grind it again, place the uniformly mixed sample in a muffle furnace, and treat it at 1200°C for 2 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain the product.

Example 6

Mix 1.629g La ₂ O ₃ and 5mL 0.01mol/L Nd(NO ₃ ) ₃ aqueous solution evenly, and grind for five minutes to grind the solid particles as finely as possible until the solution becomes a uniform slurry. Dry it, then grind it again, place the uniformly mixed sample in a muffle furnace, and treat it at 1200°C for 2 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain the product.

Example 7

1.629g La ₂ O ₃ and 5mL 0.01mol/L Eu(NO ₃ ) ₃ aqueous solution were mixed evenly, and ground for five minutes to grind the solid particles as finely as possible until the solution presented a uniform slurry. Dry it, then grind it again, place the uniformly mixed sample in a muffle furnace, and treat it at 1200°C for 2 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain the product.

Example 8

Mix 1.629g La ₂ O ₃ and 5mL 0.01mol/L Tb(NO ₃ ) ₃ aqueous solution evenly, and grind for five minutes to grind the solid particles as finely as possible until the solution becomes a uniform slurry. Dry it, then grind it again, place the uniformly mixed sample in a muffle furnace, and treat it at 1200°C for 2 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain the product.

Example 9

Mix 1.629g La ₂ O ₃ and 1mL 0.01mol/L Pr(NO ₃ ) ₃ ethanol solution evenly, and grind for five minutes to grind the solid particles as finely as possible until the solution becomes a uniform slurry. Dry it, then grind it again, place the uniformly mixed sample in a muffle furnace, and treat it at 1200°C for 3 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain the product.

Example 10

Mix 1.629g La ₂ O ₃ and 5mL 0.01mol/L Pr(NO ₃ ) ₃ ethanol solution evenly, and grind for five minutes to grind the solid particles as finely as possible until the solution becomes a uniform slurry. Dry it, then grind it again, place the homogeneously mixed sample in a muffle furnace, and treat it at 1300°C for 2 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain the product.

Example 11

Mix 1.629g La ₂ O ₃ and 5mL 0.01mol/L Pr(NO ₃ ) ₃ ethanol solution evenly, and grind for five minutes to grind the solid particles as finely as possible until the solution becomes a uniform slurry. Dry it, then grind it again, place the homogeneously mixed sample in a muffle furnace, and treat it at 800°C for 4 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain the product.

Example 12

Mix 1.629g La ₂ O ₃ and 5mL 0.01mol/L Pr(NO ₃ ) ₃ ethanol solution evenly, and grind for five minutes to grind the solid particles as finely as possible until the solution becomes a uniform slurry. Dry it, then grind it again, place the uniformly mixed sample in a muffle furnace, and treat it at 1000°C for 4 hours under airtight conditions, and wait until the temperature drops to room temperature to obtain the product.

Claims (3)

1. rare-earth trichromatic fluorescent powder, its composition is represented by following general formula: La ₂O ₃: xRE, wherein RE is rear-earth-doped ion praseodymium Pr, neodymium Nd, europium Eu or terbium Tb, mol ratio x=0.001～0.1.

2. method for preparing the described rare-earth trichromatic fluorescent powder of claim 1, this method has following steps:

[1], be equipped with liquid phase in order to the below legal system:

The lanthanum trioxide of mixed chemical calculated amount and rare earth nitrate solution also grind, and be during grinding that solid particulate is levigate as much as possible, presents uniform slurry to solution, liquid phase, described rare earth is praseodymium Pr, neodymium Nd, europium Eu or terbium Tb;

[2], with after the liquid phase oven dry, regrinding with the sample that mixes, in confined conditions in 800～1300 ℃ of thermal treatments 2～4 hours, treats that temperature reduces to room temperature after the grinding, obtains rare-earth trichromatic fluorescent powder.

3. method as claimed in claim 2 is characterized in that: described rare earth nitrate solution is selected the rare earth nitrate ethanolic soln or the aqueous solution for use.

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