KR20130096986A - Sintering technology of oxide thermoelectric materials - Google Patents

Abstract

PURPOSE: A sintering technology of oxide thermoelectric materials is provided to improve purity by heating a precursor solution containing metallic salts and a fuel at a high temperature. CONSTITUTION: A reaction solution including a metallic salt, a fuel and a solvent is prepared. The metallic salt includes a salt of Ca, a salt of Cu, and a salt of Co. The reaction solution is heated. A heating temperature is 100 to 500 °C. An oxide powder is synthesized.

Description

Sintering technology of oxide thermoelectric material {SINTERING TECHNOLOGY OF OXIDE THERMOELECTRIC MATERIALS}

The present application relates to a Ca _{3 - x} Cu _x Co ₄ O ₉ -based oxide thermoelectric material and a method of manufacturing the same.

A thermoelectric material is an energy conversion material that generates electrical energy when a temperature difference is provided between opposite ends of a material, and generates a temperature difference between opposite ends of the material when electrical energy is applied to the material. After the discovery of thermoelectric phenomena such as Seebeck effect, Peltier effect, and Thomson effect, the development of semiconductors and the development of thermoelectric performance index with high thermoelectric index have been developed since late 1930s. It is used as a special power supply device for mountain wallpaper, space, military, etc. by using power generation, and precise temperature control in semiconductor laser diode and infrared detection device using thermoelectric cooling, computer related small cooler, optical communication laser chiller, Used in chillers, semiconductor thermostats, heat exchangers, etc.

As the thermoelectric material, for example, Bi-Sb-Te-based thermoelectric materials such as a method for manufacturing a BiTe-based thermoelectric material (S. Patent No. 10-0727391), Sb ₂ Te ₃ , PbTe-Ag ₂ Te, and the like have been developed. However, these thermoelectric materials have a performance index (ZT: about 1) of commercialization level, but have low heat resistance with a melting point of 500 ° C. or lower, and thus cannot be used for high temperature waste heat, and Bi, Te, and Sb are expensive due to their small reserves. There is a problem that mass production is difficult.

The present application is a high-performance power generation Ca _{3 - x Cu x Co 4 O 9} - provides a method for producing thermoelectric material _{- x Cu x Co 4 O 9} - type thermoelectric material and liquid combustion method using the Ca _3.

However, the problem to be solved by the present application is not limited to the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

A first aspect of the present application is directed to salts of Ca, salts of Cu and Co to have a molar ratio of the metals involved in the formula represented by Ca _{3 - x} Cu _x Co ₄ O ₉ , wherein 0 ≦ x <3. Preparing a reaction solution comprising a metal salt, a fuel, and a solvent comprising a salt; A step of synthesizing oxide _{powder, Ca 3 - - x Cu x} Co 4 O 9 - and the reaction solution was heated by self blast Ca ₃ having a composition of the formula _x Cu _x Co ₄ O ₉ - based It is possible to provide a method for producing a thermoelectric material.

With a second aspect of the present application it is manufactured by the manufacturing method of the first aspect of the present _{Ca 3-x Cu x Co 4} O 9 ( where, 0 ≤ x <3 Im) a composition represented by, Ca _{3 - x} A Cu _x Co ₄ O ₉ -based thermoelectric material can be provided.

By the present application, by heating a precursor solution containing the metal salts and the fuel using a solution combustion process at high temperature it has excellent thermoelectric properties at a high temperature in a moment in a short time by self blast high purity by the size and shape uniformly Ca _{3 - x} The Cu _x Co ₄ O ₉ -based thermoelectric material powder can be easily produced. In addition, according to the present application, it is possible to obtain a high quality nanopowder for preparing the Ca _{3 - x} Cu _x Co ₄ O ₉ -based thermoelectric material. In _{addition, Ca 3 - x Cu x Co} 4 O 9 - based thermoelectric material powder is suitable for use for commercial purposes because of low-cost material having a high heat-resistant temperature.

Figure 1 according to one embodiment of the invention, a Ca _{2 .76} Cu _{0 .24} Co synthesized by the solution combustion process ₄ O ₉ The scanning electron micrograph of the powder is shown.
Figure 2 according to one embodiment of the present application, Ca ₂ Cu _{.76 0 .24} Co ₄ O ₉ The photograph (a) and SAED (selected area electron diffraction) pattern (b) analyzed by the transmission electron microscope of the powder are shown.
Figure 3 according to one embodiment of the present _{application, Ca 2 .76 Cu 0 .24 Co} 4 O 9 X-ray diffraction pattern of the synthetic powder is shown.
Figure 4 according to one embodiment of the present application, Ca ₂ Cu _{.76 0 .24} Co due to changes in the sintering temperature ₄ O ₉ X-ray diffraction pattern of the specimen is shown.
5 is according to one embodiment of the invention, a temperature-specific Ca ₂ Cu _{0 .76} Co ₄ O ₉ sintered _.24 A graph showing the scanning electron micrograph of the specimen.
Figure 6 according to one embodiment of the present _{application, Ca 2 .76 Cu 0 .24 Co} 4 O 9 sintered temperature by A graph showing the electrical conductivity of the specimen.
Figure 7 according to one embodiment of the present _{application, Ca 2 .76 Cu 0 .24 Co} 4 O 9 according to the sintering temperature It is a graph showing the thermal power of the specimen.
Figure 8 according to one embodiment of the present _{application, Ca 2 .76 Cu 0 .24 Co} 4 O 9 sintered temperature by This graph shows the output parameters of the specimen.

Hereinafter, embodiments and examples of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains.

It should be understood, however, that the present invention may be embodied in many different forms and is not limited to the embodiments and examples described herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout this specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected" but also includes the case where it is "electrically connected" do.

Throughout this specification, when a member is located "on" another member, this includes not only when one member is in contact with another member but also when another member exists between the two members.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

As used herein, the terms "about," " substantially, "and the like are used herein to refer to or approximate the numerical value of manufacturing and material tolerances inherent in the stated sense, Accurate or absolute numbers are used to prevent unauthorized exploitation by unauthorized intruders of the mentioned disclosure. Also, throughout the present specification, the phrase " step "or" step "does not mean" step for.

Throughout this specification, the term "combination of these" included in the expression of the makushi form means one or more mixtures or combinations selected from the group consisting of constituents described in the expression of the makushi form, wherein the constituents It means to include one or more selected from the group consisting of.

Hereinafter, the Ca _{3 - x} Cu _x Co ₄ O ₉ -based thermoelectric material of the present application, and a method of manufacturing the same will be described in detail with reference to embodiments, examples, and drawings. However, the present invention is not limited to these embodiments and examples and drawings.

A method for producing a Ca _{3 - x} Cu _x Co ₄ O ₉ -based thermoelectric material according to the first aspect of the present application is represented by Ca _3-x Cu _x Co ₄ O ₉ (where 0 ≦ x <3). Preparing a reaction solution comprising a metal salt, a fuel, and a solvent including a salt of Ca, a salt of Cu, and a salt of Co to have a molar ratio of metals included in the formula; And synthesizing a Ca _{3 - x} Cu _x Co ₄ O ₉ -based oxide powder having a composition of the above formula by heating and self-exploding the reaction solution, but is not limited thereto.

According to one embodiment of the present application, the heating temperature for the self-explosion may be about 100 ℃ to about 500 ℃, but is not limited thereto. The heating temperature for the self-explosion is, for example, about 100 ℃ to about 500 ℃, about 150 ℃ to about 500 ℃, about 200 ℃ to about 500 ℃, about 250 ℃ to about 500 ℃, about 300 ℃ to about 500 ℃, about 100 ℃ to about 450 ℃, about 100 ℃ to about 400 ℃, or about 100 ℃ to about 350 ℃, but is not limited thereto.

According to one embodiment of the present application, the synthesized Ca _{3 - x} Cu _x Co ₄ O ₉ -based thermoelectric material may be in the form of a nano powder, but is not limited thereto. The synthesized Ca _{3 - x} Cu _x Co ₄ O ₉ -based thermoelectric material may be a nanopowder having a form of nanoparticles having a size of about 15 nm to about 40 nm, but is not limited thereto.

According to the exemplary embodiment of the present disclosure, the salt of each metal may include, but is not limited to, nitrate, sulfate, halide, carbonate, or a combination thereof. The salt of each metal may be, for example, a nitrate of each metal, for example Ca (NO ₃ ) ₂ .xH ₂ O, Co (NO ₃ ) ₂ .6H ₂ O and Cu (NO ₃ ) _3. H ₂ O, but is not limited thereto.

According to one embodiment of the present application, the salt of each metal may be to act as an oxidizing agent, but is not limited thereto.

According to an embodiment of the present disclosure, the mixing molar ratio of the salts of the metal to the fuel may be about 0.5: about 1 to about 1: about 0.5, for example, about 1: about 1, but is not limited thereto. It is not.

According to one embodiment of the present application, the fuel is aspartic acid, glutamic acid, carbohydrazide, citric acid, alanine, glycine, glycine, urea It may include an organic compound selected from the group consisting of (urea) and combinations thereof, for example, the fuel may be aspartic acid, but is not limited thereto.

According to one embodiment of the invention, the formed _{Ca 3 - x Cu x Co 4} O 9 - the oxide powder can include but additional to calcination at about 500 to about 1,500 ℃ ℃, but is not limited thereto. The calcination temperature is, for example, about 600 ℃ to about 1,500 ℃, about 700 ℃ to about 1,500 ℃, about 800 ℃ to about 1,500 ℃, about 900 ℃ to about 1,500 ℃, about 500 ℃ to about 1,400 ℃, about 500 ℃ to about 1,300 ℃, about 500 ℃ to about 1,200 ℃, about 500 ℃ to about 1,100 ℃, about 500 ℃ to about 1,000 ℃, preferably about 900 ℃, but is not limited thereto. For example, the formed Ca _{3 - x} Cu _x Co ₄ O ₉ -based oxide powder may be calcined at about 800 ° C. for about 12 hours, but is not limited thereto.

According to one embodiment of the present application, after the calcination, the cooled Ca _{3 - x} Cu _x Co ₄ O ₉ -based oxide powder is formed by molding under normal pressure in the range of about 80 MPa to about 200 MPa from about 800 ℃ to about Sintering at about 1,500 ℃ may further include, but is not limited thereto. The pressurized pressure is, for example, about 80 MPa to about 200 MPa, about 80 MPa to about 180 MPa, about 80 MPa to about 160 MPa, about 80 MPa to about 140 MPa, about 80 MPa to about 120 MPa, about 80 MPa to about 100 MPa, about 100 MPa to about 200 MPa, about 100 MPa to about 180 MPa, about 100 MPa to about 160 MPa, about 100 MPa to about 140 MPa, about 100 MPa to about 120 MPa, about 120 MPa to It may be about 200 MPa or about 120 MPa to about 140 MPa, preferably about 150 MPa, but is not limited thereto. The sintering temperature is, for example, about 800 ℃ to about 1,500 ℃, about 800 ℃ to about 1,400 ℃, about 800 ℃ to about 1,300 ℃, about 900 ℃ to about 1,500 ℃, about 900 ℃ to about 1,400 ℃, about 900 ° C to about 1,300 ° C, about 1,000 ° C to about 1,500 ° C, about 1,000 ° C to about 1,400 ° C, about 1,000 ° C to about 1,300 ° C, about 1,100 ° C to about 1,500 ° C, about 1,100 ° C to about 1,400 ° C, or about 1,100 ° C ℃ to about 1,300 ℃ may be, but is not limited thereto.

The Ca _{3 - x} Cu _x Co ₄ O ₉ -based thermoelectric material according to the second aspect of the present application is prepared by the manufacturing method according to the first aspect of the present application, and Ca _{3 - x} Cu _x Co ₄ O ₉ (here, 0 ≦ x <3), but is not limited thereto. The _{Ca 3-x Cu x Co 4} O 9 - type thermoelectric material is, for example, Ca ₂ Cu _{.76 0 .24} Co ₄ O ₉ may be a thermal conductive material, but is not limited thereto.

According to one embodiment of the present application, the Ca _{3 - x} Cu _x Co ₄ O ₉ -based thermoelectric material may have a form of crystal grains having a size of about 10 nm to about 40 nm, but is not limited thereto. The Ca _3-x Cu _x Co ₄ O ₉ -based thermoelectric material may have a size of about 10 nm to about 40 nm, about 15 nm to about 40 nm, about 20 nm to about 40 nm, about 10 nm to about 30 nm, About 10 nm to about 20 nm, about 15 nm to about 50 nm, about 15 nm to about 40 nm, or about 15 nm to about 30 nm, but is not limited thereto.

According to one embodiment of the present application, the Ca _{3 - x} Cu _x Co ₄ O ₉ -based thermoelectric material may include pores, but is not limited thereto.

According to the exemplary embodiment of the present application, the Ca _{3 - x} Cu _x Co ₄ O ₉ -based thermoelectric material may have an electrical conductivity of about 20 Ω ¹ cm ^-1 to about 60 Ω ¹ cm ^-1 , but is not limited thereto. It doesn't happen. For example, the Ca _{3 - x} Cu _x Co ₄ O ₉ -based thermoelectric material may have an electrical conductivity of about 20 Ω ¹ cm ^-1 to about 60 Ω ¹ cm ^-1 at about 500 ° C. to about 800 ° C. However, it is not limited thereto.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[Example]

Ca _{2 .76} Cu _{0 .24} Co ₄ O ₉ Synthesis of powder

In this Example a solution combustion process to synthesize Co ₄ O ₉ thermoelectric material powder Cu _{0 .24} Ca _{2 .76.} Metal nitrate powders such as Ca (NO ₃ ) ₂ · x H ₂ O, Co (NO ₃ ) ₂ · 6H ₂ O, Cu (NO ₃ ) ₂ · 6H ₂ O (purity 99.9%, High Purity Chemicals Co., Japan) Was used as an oxidant, and aspartic acid (C ₄ H ₇ NO ₄ , 99.0%) powder (Samjeon Chemical Co., Ltd.) was used as a fuel (reducing agent). The metal nitrate and fuel weighed according to the composition were put in distilled water to make an aqueous solution, and the aqueous solution mixed with the two aqueous solutions was placed on a hot plate and heated at a temperature of 250 ° C. to 300 ° C. for 2 to 3 hours. The evaporation of moisture produced a highly viscous precursor. After that, the precursor was continuously heated, and the powder was synthesized at a high temperature (1000 ° C. to 2000 ° C.) due to the instantaneous self-explosion of the precursor. At this time, the reaction mechanism of the fuel (reducing agent) and the metal nitrate (oxidizing agent) is as follows.

Thereafter, the synthesized powder was calcined at 800 ° C. for 12 hours, and the calcined powder was put together with ethyl alcohol and zirconia balls in a zirconia container for 3 hours and 30 minutes, a planetary mill (FRITSCH pulverisette 6). After trituration with, it was dried in a drier at 60 ° C. for 24 hours. The dried powder is granulated by sieving at 120 μm, and the granulated powder is pressurized at 150 MPa to form a disk (diameter 10 mm) and a bar (5 mm x 5 mm x 25). mm) specimens were prepared. The specimen was prepared in the place 860 ℃ ~ 940 ℃ after 24 hours maintenance at a temperature in the interval 20 ℃ ronaeng to room temperature _{Ca 2 .76 Cu 0 .24 Co 4} O _9, a thermoelectric material on an alumina substrate.

result

One. Ca _{2 .76} Cu _{0 .24} Co ₄ O ₉ Microstructure and Crystal Structure of Synthetic Powder

Figure 1 is a Ca _{2 .76} Cu _{0 .24} Co synthesized by the solution combustion process ₄ O ₉ A scanning electron micrograph of the powder is shown. During powder synthesis, due to the self-explosion amounts of gas are emitted as it can be seen that _{Ca 2 .76 Cu 0 .24 Co 4} O 9 powders are mungchyeojyeo. The aggregated powders were pulverized with a planetary mill and analyzed by transmission electron microscope (a) and SAED (selected area electron diffraction) pattern (b) are shown in FIG. 2.

Figure 3 is a _{Ca 2 .76 Cu 0 .24 Co 4} O 9 X-ray diffraction pattern of the synthetic powder. The synthetic powder consists of CaCuO ₂ , Cu ₂ CoO ₃ , CaCu ₂ O ₃ , Ca ₃ Co ₂ O ₆ , and unidentified phases in addition to the Ca ₃ Co ₄ O ₉ phase. The crystallite size of the synthetic powder, calculated using the Scherrer equation, averaged 25 nm. From these results, it was found that a powder having nano-sized microcrystals was synthesized by the solution combustion method.

2. Ca _{2 .76} Cu _{0 .24} Co ₄ O ₉ Crystal Structure of Sintered Body

_{.24 .76} Ca ₂ Cu ₀ in accordance with changes in the sintering temperature Co ₄ O ₉ An X-ray diffraction pattern was obtained as shown in FIG. 4 to observe the crystal structure change of the specimen. Most of the added Cu is Ca ₃ Co ₄ O ₉ is employed in the monoclinic system subsystem _{Ca 2 .76 Cu 0 .24 Co 4} O 9 having a crystal structure (monoclinic subsystem) A solid solution was formed. In the specimens sintered at 860 ° C. and 880 ° C., in addition to the solid solution, small amounts of CaCO ₃ in a dense hexagonal crystal structure, Co ₃ O _{4 in a} dense cubic crystal structure, CaCuO _{2 in a} monoclinic structure, and a CaO phase in a cubic structure were present. CaCO ₃ with increasing sintering temperature Phase and CaCuO ₂ The intensity of the phase peaks gradually decreased, and these phases disappeared completely in specimens sintered at 900 ° C. A second phase of CoO was generated in the specimen sintered at 920 ° C. or higher, and a large amount of Ca ₃ Co ₂ O ₆ phase was produced in the specimen sintered at 940 ° C. This is considered to be because Ca ₃ Co ₄ O ₉ was decomposed into CoO and Ca ₃ Co ₂ O ₆ . Using the Scherrer equation was calculated, the grain size of the _{Ca 2 .76 Cu 0 .24 Co 4} O 9 samples, were in the range of 44-55 nm.

3. Ca _{2 .76} Cu _{0 .24} Co ₄ O ₉ Microstructure of Sintered Body

Ca ₂ Cu _{.76 0 .24} per sintering temperature Co ₄ O ₉ Scanning electron micrographs were obtained as shown in FIG. 5 to observe the microstructure of the specimen. The psalms generally had many pores. The higher the sintering temperature _{Ca 2 .76 Cu 0 .24 Co 4} O 9 The grain size and density of the specimens increased. 860 ℃ (a), 880 ℃ (b), 900 ℃ (c), 920 ℃ (d), and the Ca _{2 .76} Cu _{0 .24} Co sintered at 940 ℃ (e) ₄ O ₉ The grain sizes of the specimens were 1.29 μm, 2.11 μm, 2.44 μm, 3.07 μm, and 3.55 μm, respectively, and the densities were 2.94 g / cm ³ , 3.29 g / cm ³ , 3.40 g / cm ³ , and 3.69 g / cm, respectively. ³ , and 3.81 g / cm ³ .

4. Ca _{2 .76} Cu _{0 .24} Co ₄ O ₉ Thermoelectric Properties of Specimen

₀ Figure 6 is Ca _{2 .76-specific} sintering temperature Cu _.24 Co ₄ O ₉ A graph showing the electrical conductivity of the specimen. 500 ℃ all _{Ca 2 .76 Cu 0 .24 Co 4} O 9 at ~800 ℃ interval The specimen showed a semiconducting behavior with increasing electrical conductivity with increasing temperature. Electrical conductivity of specimens sintered at 860 ° C, 880 ° C, 900 ° C, 920 ° C, and 940 ° C was 29.5 Ω ^-1 cm ^-1 , 33.1 Ω ^-1 cm ^-1 , 44.8 Ω ^-1 cm ^- at 800 ° C, respectively. ¹ , 37.5 Ω ^-1 cm ^-1 , and 25.2 Ω ^-1 cm ^-1 . As the sintering temperature increased from 860 ° C to 900 ° C, the electrical conductivity increased due to the increase of density and grain size. Also, for specimen sintered at 860 ℃ and 880 ℃, CaCO _3, CaCuO _2, Co ₃ O _4, and the second of CaCO ₃ with CaCuO ₂ as the second phase the presence of CaO, but the sintering temperature is increased to 900 ℃ The statue disappeared. This is believed to be another cause of increased electrical conductivity. However, in the case of specimens sintered above 920 ° C., a second phase of CoO was produced. In the case of specimens sintered at 940 ° C., a second phase of Ca ₃ Co ₂ O ₆ and CaO was produced. As a result, the electrical conductivity was considerably reduced above 920 ℃. These results show that the electrical conductivity of the Ca _2.76 Cu _0.24 Co ₄ O ₉ specimen is greatly affected by the density, grain size, and the second phase. _{Ca 2 .76 Cu 0 .24 Co 4} O 9 In order to increase the electrical conductivity of the specimen, it was considered important to control the composition and manufacturing process so that the second phase does not exist.

Figure 7 _{.24 .76} Co Ca ₂ Cu ₄ O _{9 0} according to the sintering temperature The thermoelectricity of the specimen is shown. The thermoelectricity of all specimens is positive over the measured temperature range, indicating that the holes are the primary charge carriers. In addition, thermal conductivity increased with increasing sintering temperature of specimens up to 900 ° C, and the thermoelectricity of specimens sintered at temperatures above 920 ° C decreased with increasing sintering temperature. The thermoelectric values of specimens sintered at 860 ° C., 880 ° C., 900 ° C., 920 ° C., and 940 ° C. were 170 μVK ^-1 , 257 μVK ^-1 , 293 μVK ^-1 , 231 μVK ^-1 , and 82 μVK-, respectively ^{. At 1} , the specimen sintered at 940 ° C. with phase decomposition showed the smallest thermoelectric value. 8 shows the values of the output factors calculated using the electrical conductivity and the thermal power. 900 ℃ a Ca _{2 .76} Cu _{0 .24} Co ₄ O ₉ sintered at a sample value of the maximum power factor at the ^{800 ℃ (3.8 × 10 -4 WK} -2 m -1) exhibited.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments and the exemplary embodiments, and various changes and modifications may be made without departing from the scope of the present invention. It is evident that many variations are possible by those skilled in the art.

Claims (10)

A metal salt comprising a salt of Ca, a salt of Cu and a salt of Co to have a molar ratio of the metals included in the formula represented by Ca _{3 - x} Cu _x Co ₄ O ₉ , wherein 0 ≦ x <3; Preparing a reaction solution comprising a fuel and a solvent; And
Heating the reaction solution to self-exploding to synthesize a Ca _{3 -x} Cu _x Co ₄ O ₉ -based oxide powder having the composition
Method of producing a Ca _{3 - x} Cu _x Co ₄ O ₉ -based thermoelectric material comprising a.
The method of claim 1,
Heating temperature for the self-explosion is 100 ° C to 500 ° C, Ca _{3 - x} Cu _x Co ₄ O ₉ -method of manufacturing a thermoelectric material.
The method of claim 1,
The synthesized Ca _{3 - x} Cu _x Co ₄ O ₉ -based thermoelectric material is in the form of a nano-powder, manufacturing method of Ca _3-x Cu _x Co ₄ O ₉ -based thermoelectric material.
The method of claim 1,
The salt of each metal is nitrate, sulfate, halide, carbonate or a combination thereof of each metal, Ca _{3 - x} Cu _x Co ₄ O ₉ -method for producing a thermoelectric material.
5. The method of claim 4,
The salt of each metal is a method for producing a Ca _{3 - x} Cu _x Co ₄ O ₉ -type thermoelectric material, including the nitrate of each metal.
The method of claim 1,
The salt of each metal acts as an oxidizing agent, Ca _{3 - x} Cu _x Co ₄ O ₉ -method for producing a thermoelectric material.
The method of claim 1,
The mixing molar ratio of the salts of the metal to the fuel is 0.5: 1 to 1: 0.5, the manufacturing method of Ca _{3- x} Cu _x Co ₄ O ₉ -based thermoelectric material.
The method of claim 1,
The fuel is aspartic acid, glutamic acid, carbohydrazide, citric acid, alanine, glycine, urea and combinations thereof. Comprising an organic compound selected from the group consisting of, Ca _{3- x} Cu _x Co ₄ O ₉ -method for producing a thermoelectric material.
The method of claim 1,
The formed _{Ca 3 - x Cu x Co 4} O 9 - based oxide powder comprising adding to calcination at 500 ℃ to _{1,500 ℃, Ca 3 - x Cu} x Co 4 O 9 - based method for producing a thermoelectric material.
The method of claim 9,
Further comprising the sintering of the specimen obtained by molding the cooled Ca _{3 - x} Cu _x Co ₄ O ₉ -based oxide powder after calcination under normal pressure in the range of 80 MPa to 200 MPa at 800 ℃ to 1500 ℃, _{3 - x} Cu _x Co ₄ O ₉ -method of manufacturing a thermoelectric material.

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