JP6865951B2 - P-type thermoelectric semiconductor, its manufacturing method and thermoelectric power generation element using it - Google Patents

Description

The present invention relates to a p-type thermoelectric semiconductor, a method for manufacturing the same, and a thermoelectric power generation element using the same, and particularly to a p-type thermoelectric transformation semiconductor having high thermal operation stability, a method for manufacturing the same, and a thermoelectric power generation element using the same.

Even in Japan, where energy conservation has progressed particularly in the world, about 3/4 of the primary supply energy is currently discarded as heat energy in waste heat recovery. Under such circumstances, thermoelectric power generation devices are attracting attention as solid-state devices capable of recovering thermal energy and directly converting it into electrical energy.

Since the thermoelectric power generation element is a direct conversion element to electric energy, there are merits such as ease of maintenance and scalability due to the absence of moving parts. For this reason, active material research is being conducted on thermoelectric semiconductors.

For use in thermoelectric power generation, it is desirable to form the element without containing rare earth elements, which are rare, expensive, and tend to have resources unevenly distributed in a specific area.
Transition metal sulfides are known as systems that exhibit high thermoelectric performance (power factor, etc.), as shown in Non-Patent Documents 1 and 2. However, there are many compounds having a high power factor but a relatively high thermal conductivity, and a system having a lower thermal conductivity is desired. In addition, many compounds have thermal instability such as copper being diffused by heat. Considering the actual operating environment of the thermoelectric element, it was necessary to find a compound having excellent thermal operational stability.
In such transition metal sulfides, if a semiconductor with high thermal operation stability (stability of thermoelectric characteristics in a high temperature environment) can be found while taking advantage of its high power factor, it can be widely applied as a thermoelectric semiconductor or a thermoelectric power generation element. It will be possible. Therefore, the development of a transition metal sulfide thermoelectric semiconductor that meets the requirements has been strongly desired.

Incidentally, copper (Cu), with respect to CuCr ₂ S ₄ material is a ternary compound consisting of chromium (Cr) and sulfur (S), as in Non-Patent Document 3, although the thermoelectric properties have been investigated, which is It was a metallic compound and had low thermoelectric performance like the conventional metallic compounds.

Japanese Unexamined Patent Publication No. 2008-177356

Chem. Int. Ed. , 2015, vol. 54, pp. 12909-12913. Sci. Technol. Adv. Mater. , 2012, vol. 13, p. 053003 Thermoelectric materials, 2000, p. 626 Condensed Matter, 1980, vol. 12b, p. 409 J. Magn. Magn. Mater. , 1997, vol. 175, pp. 299-303 J. Alloys Compd. , 2004, vol. 377, pp. 53-58 Phys. Chem. Miner. , 2003, vol. 30, p. 463

The object of the present invention is to solve the above-mentioned conventional problems, to provide a thermoelectric semiconductor which is excellent in thermoelectric characteristics such as a power factor and which secures high thermal operation stability, and further to utilize such a thermoelectric semiconductor. It is to provide a thermoelectric power generation element.

_{CuCr 2-x} Sb _x S _{4 obtained by doping the CuCr 2} S ₄ material, which is one of the transition metal sulfides, with an appropriate amount of antimony (Sb) substituted is used as the thermoelectric semiconductor material. As a result, the metallic CuCr ₂ S ₄ is replaced with a semiconductor having a relatively high electric conductivity, a large Seebeck coefficient, and a low thermal conductivity, and the problem of the thermoelectric semiconductor is solved. CuCr _2-x Sb _x S ₄ is a p-type semiconductor.
The configuration of the present invention is shown below.

(Structure 1)
A quaternary p-type thermoelectric semiconductor containing sulfide.
A p-type thermoelectric semiconductor characterized in that the composition of the thermoelectric semiconductor has the composition shown below.
CuCr _2-x Sb _x S ₄
(Here, x is 0.2 or more and 0.5 or less)

(Structure 2)
The p-type thermoelectric semiconductor according to the configuration 1, wherein x is 0.22 or more and 0.5 or less.

(Structure 3)
The p-type thermoelectric semiconductor according to the configuration 1, wherein x is 0.22 or more and 0.35 or less.

The configuration of the present invention is shown below.
(Structure 4)
The p-type thermoelectric semiconductor according to any one of configurations 1 to 3, wherein the crystal structure of the thermoelectric semiconductor is a spinel structure in which chromium or antimony is arranged at 16c in Wyckoff Position.

(Structure 5)
The process of preparing a raw material mixture in which a copper source, a chromium source, an antimony source and a sulfur source are mixed, and
Having a step of calcining the raw material mixture,
A method for producing a p-type thermoelectric semiconductor, which comprises producing a p-type thermoelectric semiconductor having the following composition.
CuCr _2-x Sb _x S ₄
(Here, x is 0.2 or more and 0.5 or less)

(Structure 6)
The method for manufacturing a p-type thermoelectric semiconductor according to the configuration 5, wherein x is 0.22 or more and 0.5 or less.

(Structure 7)
The method for manufacturing a p-type thermoelectric semiconductor according to the configuration 5, wherein x is 0.22 or more and 0.35 or less.

(Structure 8)
The method for producing a p-type thermoelectric semiconductor according to any one of configurations 5 to 7, wherein at least one of the copper source, the chromium source, the antimony source, and the sulfur source is a simple substance of the element.

(Structure 9)
The copper source, chromium source, antimony source and sulfur source include at least one selected from the group consisting of copper sulfide, chromium sulfide, antimony sulfide, copper chromium alloy, copper antimony compound, and chromium antimony compound. The method for producing a p-type thermoelectric semiconductor according to any one of Structures 5 to 8, wherein the method is characterized by the above.

(Structure 10)
The method for producing a p-type thermoelectric semiconductor according to any one of configurations 5 to 9, wherein the firing is performed at a temperature of 550 ° C. or higher and 850 ° C. or lower in a vacuum or an inert atmosphere.

(Structure 11)
The method for producing a p-type thermoelectric semiconductor according to any one of configurations 5 to 10, wherein the firing is carried out for 1 hour or more.

(Structure 12)
The method for producing a p-type thermoelectric semiconductor according to any one of configurations 5 to 11, wherein after firing, additional firing is performed at least once, in which crushing is performed and firing is performed again.

(Structure 13)
After the calcination or the additional firing, p-type thermoelectric semiconductor manufacturing method according to Structure 1 2, characterized in that annealing.

(Structure 14)
The method for manufacturing a p-type thermoelectric semiconductor according to the configuration 13, wherein the annealing is performed at a temperature of 550 ° C. or higher and 750 ° C. or lower.

(Structure 15)
The method for manufacturing a p-type thermoelectric semiconductor according to the configuration 13 or 14, wherein the annealing is 1 hour or more and 100 hours or less.

(Structure 16)
A thermoelectric power generation device in which a p-type semiconductor and an n-type semiconductor are integrated, wherein the p-type thermoelectric semiconductor according to any one of configurations 1 to 4 is used as the p-type semiconductor. element.

According to the present invention, it is possible to provide a p-type thermoelectric semiconductor having high thermoelectric performance and high thermal operation stability. Further, it is possible to provide a thermoelectric power generation element having high thermoelectric performance and high thermal operation stability.

The schematic diagram which shows the structure of the thermoelectric semiconductor of this invention. The X-ray diffraction pattern figure of the thermoelectric semiconductor powder sample of an Example. The characteristic diagram which shows the electric conductivity of the thermoelectric semiconductor of an Example. The characteristic figure which shows the Seebeck coefficient of the thermoelectric semiconductor of an Example. The characteristic figure which shows the thermoelectric power factor of the thermoelectric semiconductor of an Example. The characteristic figure which shows the thermal conductivity of the thermoelectric semiconductor of an Example. The characteristic figure which shows the dimensionless figure of merit of the thing thermoelectric semiconductor of an Example. The cross-sectional schematic diagram which shows the structure of the thermoelectric power generation element of this invention.

(Thermoelectric semiconductor)
First, the thermoelectric semiconductor of the present invention will be described.

The thermoelectric semiconductor of the present invention is a quaternary sulfide semiconductor composed of copper (Cu), chromium (Cr), antimony (Sb) and sulfur (S), and is a p-type semiconductor having the composition shown in the following formula.
CuCr _2-x Sb _x S ₄
(Here, x is 0.2 or more and 0.5 or less)

This thermoelectric semiconductor is a _{spinel-type compound made of CuCr 2} S ₄ substituted and doped with Sb. The structure is considered to be a legislative crystal system structure shown in FIG. 1 from the measurement results of Rietveld analysis and X-ray diffraction. That is, the structure is a spinel structure in which Cr or Sb is arranged at 16c in Wyckoff Position. It is desirable that Sb is substituted (substituted dope) at the location of Cr in this way, but if it is about several mol%, it is also allowed to be substituted at the portion of S.
Further, the thermoelectric semiconductor is preferably a single crystal, but a polycrystal is also allowed.

Further, from the viewpoint of thermoelectric operation and stability of characteristics, _{it is desirable that CuCr 2-x} Sb _x S ₄ has a single phase. When x is less than 0.2, multiple phases may appear and become unstable. In that case, the thermoelectric operation and its characteristics tend to be unstable, so x is required to be 0.2 or more. When x is 0.22 or more, a particularly high power factor PF and a high dimensionless figure of merit ZT can be obtained, which is more preferable.

On the other hand, when x exceeds 0.5, the insulating property becomes stronger and the thermal conductivity σ or, for example, the thermal conductivity κ at a high temperature of 400 ° C. or higher becomes low, and sufficient thermoelectric characteristics (power) are obtained. Factor PF and dimensionless performance index ZT) are difficult to obtain. Therefore, x is required to be 0.5 or less. Further, from the viewpoint of ensuring sufficient semiconductor properties and obtaining a high power factor PF and a high dimensionless figure of merit ZT, x is more preferably 0.4 or less, and even more preferably 0.35 or less. Preferred (see Example 1).

One of the features of the material of the present invention is that the bond length between the mixed atomic site consisting of Cr and Sb (Cr / Sb mixed atomic site) and the S atomic site is short, and the Cr / Sb mixed atomic site and the S atomic site are In the atomic plane to be formed, the arrangement is such that the S atoms are waving up and down. _{The bond lengths L Cr / Sb-S} between the Cr / Sb mixed atomic site and the S atomic site _{are 2. When the x of CuCr 2-x} Sb _x S ₄ is 0.22, 0.3, 0.5, respectively. It is 4200 nm, 2.4199 nm and 2.4339 nm. These values were obtained based on the X-ray diffraction pattern.
On the other hand, in ordinary compounds containing Sb and S, the bond length of Sb-S is long. For example _{, in stibnite Sb 3} S ₂ , an Sb-S bond length of 2.5 to 3.6 nm has been reported. (See Non-Patent Document 7).

In Non-Patent Document 4, _{it is reported that the CuCr 2} S ₄ compound decomposes at 445 ° C to 550 ° C under vacuum. _{The CuCr 2-x} Sb _x S ₄ (x is 0.2 or more and 0.5 or less) produced by the present inventors is excellent in stability without showing decomposition up to a high temperature of at least 650 ° C. under vacuum. It is considered that this is due to the unexpected bond strength of the above Cr / Sb mixed atom site and S atom site, which is realized regardless of doping the large Sb atom. Such high-temperature stability is rare in Cu-based sulfide thermoelectric materials, and is useful in practical application environments.

Further, CuCr _2-x Sb _x S ₄ (x is 0.2 or more and 0.5 or less) has a simple tetragonal structure, but is considered to be caused by the above-mentioned crystal structural characteristics. It has been found that the product exhibits a characteristically low thermal conductivity (2 W / m · K or less at room temperature to 650 ° C., see FIG. 7). This newly discovered structurally derived feature makes it possible to have both a large Seebeck coefficient α (see FIG. 4) and a high electrical conductivity σ (see FIG. 3), as shown in Example 1 below, which is high. Thermoelectric performance (see FIGS. 5 and 7) can be obtained.

_{As described in Non-Patent Document 3, the thermoelectric properties of CuCr 2} S ₄ without Sb substitution doping have been investigated, but it is a metallic compound and has thermoelectric performance similar to that of a conventional metallic compound. Was low.
Further, Sb-substituted CuCr ₂ S ₄ are found in Non-Patent Documents 5 and 6, but these have been investigated in terms of magnetic properties (magnetic resistance) with spintronics application in mind. In Non-Patent Documents 5 and 6, although the electrical resistance is measured, the resistivity required for the evaluation of thermoelectric characteristics is unknown, the temperature is low below room temperature, which is difficult to apply as a thermoelectric element, and the Seebeck coefficient and There is no description about thermal conductivity.
CuCr _2-x Sb _x S ₄ has high thermal operating stability of the present invention, relatively high electrical conductivity, large result that combine properties suitable for use as a material for thermoelectric element as Seebeck coefficient and low thermal conductivity unexpected This has been derived based on detailed crystal structure analysis and experiments.

Next, the method for manufacturing the thermoelectric semiconductor of the present invention will be described.
In the production of the p-type thermoelectric semiconductor of the present invention, first, a copper source, a chromium source, a strontium source and a sulfur source as raw materials are prepared. These materials may be the respective single elements, namely Cu, Cr, Sb and S elements themselves, or as starting materials copper sulfide, chromium sulfide, antimony sulfide, copper chromium alloy, copper antimony compound, and chromium. Antimony compounds and the like may be used. Moreover, these combinations may be used. It is preferable that at least one of the copper source, the chromium source, the strontium source, and the sulfur source is a simple substance of the element because it is easy to control the amount of the raw material.

The state of these raw materials is preferably in the form of powder. If the particle size is extremely fine, such as nanoparticles, the ratio of surface area to volume becomes significantly high and surface oxides can be easily taken in, which is not preferable. Further, if the particle size is granular or lumpy so as to reach the unit of mm, these elements are sufficiently mixed to take a long time to produce a homogeneous crystal, which is not preferable in terms of production efficiency.

These raw materials are preferably stored and handled in a vacuum or in an atmosphere of an inert gas such as argon. This is to reduce surface oxidation and adsorbed water as much as possible to prevent oxygen and water from being taken into the crystals. For this reason, these raw materials are preferably stored in vacuum-sealed or inert gas-sealed ampoules and handled in a glove box filled with an inert gas.

Next, these raw materials are weighed using an electronic balance or the like so that the final composition is the desired CuCr _2-x Sb _x S ₄ (raw material composition), and then these raw materials are mixed to prepare a mixture. .. Here, x is a predetermined value within the range of 0.2 or more and 0.5 or less. Sulfur (S) becomes a gas, and a portion that is not incorporated into the crystal is generated. Therefore, an appropriate amount that is also estimated for that portion is weighed.

The mixture is sealed with a vacuum or an inert gas such as argon and then fired. The firing temperature is preferably 550 ° C. or higher and 850 ° C. or lower, and the firing time is preferably 1 hour or longer. Further, there is no problem even if firing is performed for a long time such as 24 hours, but in that case, time and power consumption are wasted.
It is also preferable to press-mold this mixture prior to this firing.
Further, although there is a furnace as a method of firing, the method is not limited to the furnace, and for example, discharge plasma sintering or hot pressing may be used.

Repeated firing of one or more times (where the cycle of crushing using a ball mill or the like is repeated after firing) and annealing at 550 ° C or higher and 750 ° C or lower cause Sb to be more incorporated into crystals and replaced, so that doping is sufficient. It is preferable because it can be performed. This annealing is preferably performed for 1 hour or more and 100 hours or less. Annealing of the above range improves the homogeneity of the crystal composed of _{CuCr 2-x Sb x S 4} , such as thermal behavior becomes stable thermoelectric semiconductor obtained.

(Thermoelectric power generation element)
Here, the thermoelectric generation element will be described.
As shown in FIG. 8, for example, the thermoelectric power generation element 31 has an n-type thermoelectric semiconductor 32 and a p-type thermoelectric semiconductor between the electrode 35 on the low temperature side and the electrode 34 on the high temperature side via these electrodes. 33 is an element having a structure electrically arranged in series.

When the thermoelectric power generation element 31 is installed in an environment where the electrode 34 has a high temperature and the electrode 35 has a lower temperature than that, and the electrode at the end is connected to an electric circuit or the like, a voltage is generated due to the Seebeck effect, as shown by the arrow. A current flows through the electrode 35 → n-type thermoelectric semiconductor 32 → electrode 34 → p-type thermoelectric semiconductor 33. That is, the electrons in the n-type thermoelectric semiconductor 32 obtain the thermal energy from the high-temperature electrode 34 and move to the low-temperature electrode 35 to release the thermal energy there, whereas the holes of the p-type thermoelectric semiconductor are the high-temperature electrodes. A current flows by the principle that heat energy is obtained from 34 and moved to a low temperature electrode 35 where the heat energy is released.

As the p-type thermoelectric semiconductor 33, a p-type thermoelectric semiconductor of the present invention consisting of CuCr _{2-x Sb} x _{S 4} in which the x and 0.2 to 0.5. The n-type thermoelectric semiconductor is not particularly limited as long as it is an n-type thermoelectric semiconductor, and for example, an n-type thermoelectric semiconductor made _{of a CuFeS 2-based material having a calcopyrite crystal structure can be preferably mentioned.}
As a result, stable heat recovery of thermal operation becomes possible, and the range of available heat is greatly expanded.

Hereinafter, the present invention will be described in more detail by way of examples, but these examples are given here only for the purpose of assisting the understanding of the present invention, and the present invention is not limited thereto.

(Example 1)
Example 1 is an example in which a quaternary p-type thermoelectric semiconductor made of copper, chromium, antimony and sulfur is produced.
The material composition _is a _{CuCr 2-x Sb x S 4} , to produce a p-type thermoelectric semiconductor by changing the 0.22,0.3 and 0.5 x, and evaluated the thermoelectric properties.

<Manufacturing of thermoelectric semiconductors>
First, as a raw material, copper (Cu) (powder, Aldrich Co., Ltd., 99.5%),
Chromium (Cr) (powder, Fruuchi Chemical Co., Ltd., 99.99%), antimony (powder, Aldrich Co., Ltd., 99.5%) and sulfur (S) (powder, Aldrich Co., Ltd., 99.5%) ) Was prepared. These raw materials are sealed and stored with an inert gas (argon gas).
Next, when x is 0.30 in a glove box filled with an inert gas (argon gas), Cu, Cr, Sb and S are 0.4055 g, 0.5590 g and 0.2315 g, respectively. And 0.8610 g electronic balance was used for weighing. Here, since S was vaporized in the following firing step and a part of it was not incorporated into the thermoelectric semiconductor material, an amount larger than the composition ratio of the thermoelectric semiconductor material to be produced was weighed.
Then, these powders were sufficiently mixed, and the mixture was press-molded (CIP) using a hand press machine.

Then, the press-molded sample was placed in a quartz tube, evacuated, sealed (sealed), and then the sample was fired. There, the temperature was raised from room temperature to 750 ° C. over 8 hours at a constant temperature rise rate, and then fired at 750 ° C. for 15 hours. After that, it was slowly cooled to room temperature over 8 hours. This process is not essential for phase synthesis, but the addition of this process resulted in a more uniform sample.

The obtained sample was pulverized using a mortar, and the above molding, heating, and reaction processes were repeated after changing 750 ° C to 650 ° C. Here, there is no change in the time of each process.
Finally, sintering was performed by a discharge plasma sintering apparatus, and the molded sample was annealed at 650 ° C. for 48 hours in an argon atmosphere to prepare a sample of _{CuCr 1.70} Sb _0.30 S _4. Here, for sintering, Dr. Fuji Radio Industrial Co., Ltd. Using SINTER, the sintering conditions were a pressure of 50 MPa, a temperature of 600 ° C., and 5 minutes.

Further, by performing the same process by changing the ratio of the raw materials, CuCr _2-x Sb _x S ₄ (x = 0.22, x = 0.30, x = 0.35, x = 0.50) Each sample was prepared.

<Characteristics of thermoelectric semiconductors>
Due to the production conditions of annealing at 650 ° C. for 48 hours in an argon atmosphere, changes in the material (crystal) are unlikely to occur at such a high temperature. In addition, in the thermal conductivity measurement up to 650 ° C. performed in vacuum, no change was observed in the thermoelectric characteristics in the repeated measurements. From these facts, it can be said that the thermoelectric semiconductor made of this material is a thermoelectric semiconductor having high thermoelectric operation stability capable of stable thermoelectric conversion even in a high temperature operating environment.

The X-ray diffraction pattern was measured using the fired sample. The result is shown in FIG. In the measurement of this X-ray diffraction pattern, only the first firing at 750 ° C. for 15 hours was performed, and remolding by pulverization and refiring and discharge plasma sintering (SPS) was not performed.
Based on this X-ray diffraction pattern, the Rietveld analysis, it was confirmed that a substantially single phase of spinel structure (MgAl ₂ O ₄ -type structure) Sample is obtained.
_{The actual measurement data Yobs} is shown in the portion other than the lower part in FIG. 2, and the difference _Yobs −Y _{calc from the calculated value Y calc} assuming the crystal structure from the actual measurement as follows is shown in the lower part. The calculated value Y _calc was obtained by assuming that the sample had a crystal structure (spinel structure) of scutertite and fitting it to a diffraction pattern as much as possible.
From the difference _Y obs _{-Y calc} calculation from Figure 2 and measured as apparent is very small, the structure of the produced samples, replace a portion of the Cr spinel crystals consisting of CuCr ₂ S ₄ to Sb It can be said that it is a spinel structure in which chromium or antimony is arranged at 16c in Wyckoff Position. The crystal structure is shown in FIG.

3 to 7 show the measurement results of the electric conductivity σ, the Seebeck coefficient α, the power factor PF, the thermal conductivity κ, and the dimensionless performance index ZT of the thermoelectric semiconductor of the thermoelectric transformation semiconductor, respectively. Here, this measurement sample is pulverized once after the completion of firing, and then remolded by discharge plasma sintering (SPS).

As can be seen from FIG. 3, the relatively high electrical conductivity σ of ^{2.5 to 4.2 × 10 4} S / m due to the substitution doping of Sb, especially in the samples of x = 0.22 and x = 0.30. Has been obtained. At the same time, as shown in FIG. 4, a relatively high Seebeck coefficient α of 80 to 160 μV / K is obtained in the measurement temperature range. Although x = 0 is metallic, it was converted to a semiconductor by Sb substitution doping, and a high Seebeck coefficient α was expressed.
On the other hand, the sample with x = 0.5 is directed toward the insulator, and as shown in FIGS. 5 and 7, the thermoelectric performance represented by the power factor PF and the dimensionless performance index ZT is x. Inferior to = 0.22, x = 0.30 and x = 0.35.
Further, as shown in FIG. 6, the thermal conductivity κ is a value of 2 W / m · K or less, which is characteristically low as a transition metal sulfide in the entire temperature range in the measurement region, and is Cr / Sb. It can be seen that the substitution doping and the crystal structure of the above are working.

As described above, the sample was SPS-sintered, and the purpose of this is to make the sample dense and to mold it. In the present invention, SPS sintering is not essential, but it lowers the electrical resistance and improves the thermoelectric performance.

(Example 2)
Example 2 is an example in which the thermoelectric power generation element 31 is manufactured (see FIG. 8).
In the manufactured thermoelectric power generation element 31, the n-type thermoelectric semiconductor 32, which is a thermoelectric material chip, is bonded to the electrode 35 on the low temperature side by soldering, and the end on the opposite side of the n-type thermoelectric semiconductor 32 and the high temperature side. The electrode 34 is also joined by solder. Further, the same electrode 34 and the p-type thermoelectric semiconductor 33 which is a thermoelectric material chip are bonded, and the opposite end of the p-type thermoelectric semiconductor 33 is bonded to another electrode 35 to which another n-type thermoelectric semiconductor 32 is bonded. ing. With such a configuration, the thermoelectric power generation element 31 is electrically connected in series.

As p-type thermoelectric semiconductor 33 in the thermoelectric power generating device having such a structure, with _CuCr 1.7 _Sb 0.3 _{S 4} material prepared in Example 1. As a result, it has become possible to perform heat recovery under higher thermal operational stability than before.

(Comparative Example 1)
Comparative Example 1 _is a case of the x = 0.18 in the _CuCr 2-x _Sb x _{S 4} material were examined and the lattice parameter (lattice parameter). The method for preparing this sample is the same as that of Example 1 except that the weighing of the raw materials is finally changed to CuCr _1.82 Sb _0.18 S _4. As a result, in Comparative Example 1 in which x = 0.18, phase division was observed, and the lattice parameters were 0.9847 nm and 0.9918 nm. When x was 0.22, 0.3, and 0.5, the lattice parameters were 0.9922 nm, 0.9950 nm, and 1.0000 nm, respectively, and no phase division was observed. Phase splitting is a source of instability in thermoelectric properties.

As described above, since the p-type thermoelectric semiconductor and the thermoelectric power generation element according to the present invention are elements that directly convert heat having high thermoelectric conversion efficiency and high thermal operation stability into electricity, they are widely used in industry such as waste heat recovery. It is expected.

31: Thermoelectric power generation element 32: n-type thermoelectric semiconductor 33: p-type thermoelectric semiconductor 34: Electrode 35: Electrode

Claims (15)

A quaternary p-type thermoelectric semiconductor containing sulfide.
A p-type thermoelectric semiconductor characterized in that the composition of the thermoelectric semiconductor has the composition shown below.
CuCr _2-x Sb _x S ₄
(Here, x is 0.2 or more and 0.5 or less) The p-type thermoelectric semiconductor according to claim 1, wherein the x is 0.22 or more and 0.5 or less. The p-type thermoelectric semiconductor according to claim 1, wherein the x is 0.22 or more and 0.35 or less. The p-type thermoelectric semiconductor according to any one of claims 1 to 3, wherein the crystal structure of the thermoelectric semiconductor is a spinel structure in which chromium or antimony is arranged at 16c in Wyckoff Position. The process of preparing a raw material mixture in which a copper source, a chromium source, an antimony source and a sulfur source are mixed, and
Having a step of calcining the raw material mixture,
A method for producing a p-type thermoelectric semiconductor, which comprises producing a p-type thermoelectric semiconductor having the following composition.
CuCr _2-x Sb _x S ₄
(Here, x is 0.2 or more and 0.5 or less) The method for manufacturing a p-type thermoelectric semiconductor according to claim 5, wherein x is 0.22 or more and 0.5 or less. The method for manufacturing a p-type thermoelectric semiconductor according to claim 5, wherein x is 0.22 or more and 0.35 or less. The method for producing a p-type thermoelectric semiconductor according to any one of claims 5 to 7, wherein at least one of the copper source, the chromium source, the antimony source and the sulfur source is a simple substance of the element. The copper source, chromium source, antimony source and sulfur source include at least one selected from the group consisting of copper sulfide, chromium sulfide, antimony sulfide, copper chromium alloy, copper antimony compound, and chromium antimony compound. The method for producing a p-type thermoelectric semiconductor according to any one of claims 5 to 8, wherein the p-type thermoelectric semiconductor is manufactured. The method for producing a p-type thermoelectric semiconductor according to any one of claims 5 to 9, wherein the firing is performed at a temperature of 550 ° C. or higher and 850 ° C. or lower in a vacuum or an inert atmosphere. The method for producing a p-type thermoelectric semiconductor according to any one of claims 5 to 10, wherein after firing, additional firing is performed at least once, in which crushing is performed and firing is performed again. The method for producing a p-type thermoelectric semiconductor according to claim 11, wherein annealing is performed after the firing or the additional firing. The method for manufacturing a p-type thermoelectric semiconductor according to claim 12, wherein the annealing is performed at a temperature of 550 ° C. or higher and 750 ° C. or lower. The method for producing a p-type thermoelectric semiconductor according to claim 12 or 13, wherein the annealing is 1 hour or more and 100 hours or less. A thermoelectric power generation device in which a p-type semiconductor and an n-type semiconductor are integrated, wherein the p-type thermoelectric semiconductor according to any one of claims 1 to 4 is used as the p-type semiconductor. Power generation element.

Images