JP6567991B2 - Method for producing thermoelectric conversion material - Google Patents

Description

  The present invention relates to a method for producing a thermoelectric conversion material.

  In recent years, in order to reduce carbon dioxide emissions due to the global warming problem, there has been an increasing interest in technologies that reduce the proportion of energy obtained from fossil fuels. A thermoelectric conversion material capable of directly converting thermal energy into electric energy is exemplified. A thermoelectric conversion material is a material that enables direct conversion from heat to electrical energy without the need for a two-step process of converting heat to kinetic energy and then to electrical energy, as in thermal power generation. is there.

  The conversion from heat to electrical energy is performed using the temperature difference between both ends of the bulk body formed from the thermoelectric conversion material. The phenomenon in which voltage is generated due to this temperature difference was discovered by Seebeck and is called the Seebeck effect. The performance of this thermoelectric conversion material is represented by a figure of merit Z obtained by the following equation.

Z = α ² σ / κ (= PF / κ)

Here, α is the Seebeck coefficient of the thermoelectric conversion material, σ is the conductivity of the thermoelectric conversion material, and κ is the heat conductivity of the thermoelectric conversion material. The terms α ² σ are collectively referred to as an output factor PF. Z has a dimension of the reciprocal of temperature, and ZT obtained by multiplying the figure of merit Z by the absolute temperature T is a dimensionless value. This ZT is called a dimensionless figure of merit and is used as an index representing the performance of the thermoelectric conversion material. Therefore, a lower thermal conductivity κ is required to improve the performance of the thermoelectric conversion material, as is apparent from the above formula.

  Conventionally, in thermoelectric conversion materials, attempts have been made to combine a base material and a dispersion material in order to improve performance by reducing thermal conductivity.

  For example, in Patent Document 1, a reducing agent and a dispersion material are mixed in a salt solution of a raw material substance of a thermoelectric conversion material (for example, an ethanol solution), the mixture is stirred and aged, and then hydrothermal treatment is performed on the mixture. A method of manufacturing a nanocomposite thermoelectric material is described, including performing. However, there is no specific mention of a combination of a base material, a dispersion material, and a solvent for sufficiently combining the base material and the dispersion material, and an index for selection.

  Patent Document 2 describes core-shell type nanoparticles having a core part and a shell part that covers the core part and whose constituent material is InSb. Patent Document 2 describes that in the manufacturing method, an organic compound having a functional group that can be attached to a base material constituting material is used in order to improve dispersibility. The use of the organic compound to reduce the conductivity is not described. The said organic compound is removed in the manufacturing process of the thermoelectric conversion material using a core-shell type nanoparticle, and, thereby, does not reduce the thermal conductivity of the thermoelectric conversion material.

  Therefore, in order to reduce thermal conductivity, development of a method for producing a thermoelectric conversion material in which a base material and a dispersion material are sufficiently combined has been demanded.

Japanese Patent Laying-Open No. 2015-195359 JP 2007-21670 A

  An object of this invention is to provide the manufacturing method of the thermoelectric conversion material by which the base material and the dispersing material were fully compounded.

  In the production of thermoelectric conversion materials, the inventors have reduced the affinity of the dispersion material and the solvent to a certain degree relative to the affinity of the dispersion material and the matrix material, thereby reducing the dispersion of the matrix material and the dispersion material. It was found that the material can be sufficiently combined.

That is, the present invention includes the following inventions.
(1) Next step:
(A) a solution containing a precursor of at least one matrix constituent element selected from Bi and Sb, a precursor of at least one matrix constituent element selected from Te and Se, and a solvent; A step of mixing a reducing agent to obtain matrix composite particles,
(B) The solvent of the solution containing the composite particles obtained in step (a) is optionally replaced with another solvent, and a dispersion material is added to the solution, and (c) obtained in step (b). A method for producing a thermoelectric conversion material comprising a step of heat-treating a solution containing composite particles and a dispersion material,
The Hansen solubility parameter (HSP) distance Ra between the dispersion material and the base material and the Hansen solubility parameter (HSP) distance Rb between the dispersion material and the solvent of the solution containing the composite particles to which the dispersion material is added are represented by the following formula (I):
Ra-Rb ≦ 3.0 (I)
Meet the above method.
(2) The method according to (1), wherein the Hildebrand solubility parameter (SP) value of the solvent is 21.3 or more.

  According to the method for producing a thermoelectric conversion material of the present invention, the base material and the dispersion material can be sufficiently combined. According to the method for producing a thermoelectric conversion material of the present invention, it is possible to select an appropriate solvent, so that the composite can be promoted even with a small amount of the dispersing material.

FIG. 1 shows the HSP distance Ra between the dispersion material and the base material—the value of the HSP distance Rb between the dispersion material and the solvent, and the dispersion component (Si) for the thermoelectric conversion materials of Example 1-3 and Comparative Example 1. It is a graph which shows the relationship with compound amount. FIG. 2 is a graph showing the relationship between the Hildebrand SP value of the solvent and the amount of the dispersant component (Si) combined for the thermoelectric conversion materials of Examples 1-3 and Comparative Example 1.

The present invention includes the following steps: (a) a precursor of at least one matrix constituent element selected from Bi and Sb; and a precursor of at least one matrix constituent element selected from Te and Se; A step of mixing a solution containing a solvent and a reducing agent to obtain base material composite particles, (b) a solvent in the solution containing the composite particles obtained in step (a) is optionally replaced with another solvent And (c) a method of manufacturing a thermoelectric conversion material, comprising the step of heat-treating the solution containing the composite particles and the dispersion obtained in step (b). The Hansen solubility parameter (HSP) distance Ra between the base material and the Hansen solubility parameter (HSP) distance Rb between the dispersion material and the solvent containing the composite particles to which the dispersion material is added is expressed by the following formula (I): Ra-Rb ≦ 3.0 Hereinafter also referred to as the production method of the present invention). In the production of a (Bi, Sb) ₂ (Te, Se) ₃ thermoelectric conversion material, the inventors have made the affinity between the dispersion material and the solvent relatively to the affinity between the dispersion material and the base material. It was found that the composite amount can be significantly increased by reducing (HSP distance Ra between dispersion material and base material−HSP distance Rb = 3.0 (MPa ^1/2 ) or less between dispersion material and solvent). . The production method of the present invention increases the composite amount of the dispersion material and the base material as compared with the conventional technique in which the composite amount is increased by improving the dispersibility (affinity) of the dispersion material / base material and the solvent. be able to. Specifically, the manufacturing method of the present invention has a relatively high affinity between the dispersion material and the base material with respect to the affinity between the dispersion material and the solvent, thereby increasing the binding property between the dispersion material and the base material. Can be made. As a result, the composite amount of the dispersion material and the base material increases, and the thermal conductivity can be greatly reduced. In addition, since the production method of the present invention makes it possible to select an appropriate solvent, since the composite can be promoted even with a relatively small amount of the dispersing agent, a decrease in electrical conductivity is conventionally achieved. This can also suppress the thermoelectric conversion efficiency ZT.

Here, the Hansen solubility parameter (hereinafter also referred to as “HSP”) is a parameter representing the solubility characteristics between substances. In this specification, the Hansen solubility parameter (HSP) is a vector quantity parameter obtained by dividing the Hildebrand solubility parameter (SP) into three cohesive energy components of London dispersion force, dipole force and hydrogen bond force. means. In the present specification, a component corresponding to the London dispersion force of HSP is a dispersion term (hereinafter also referred to as “δd”), a component corresponding to the force between dipoles is referred to as a polar term (hereinafter also referred to as “δp”), A component corresponding to the hydrogen bond strength is referred to as a hydrogen bond term (hereinafter also referred to as “δh”). And the total HSP is:
Hildebrand SP ² = total HSP ² = δd ² + δp ² + δh ²
It is represented by Since HSP is a vector quantity, it is known that there are almost no pure substances having exactly the same value. A database of HSPs of commonly used substances has been constructed. Therefore, those skilled in the art can obtain the HSP value of a desired substance by referring to the database. Even if a substance has no HSP value registered in the database, those skilled in the art can calculate the HSP value from its chemical structure by using computer software such as Hansen Solubility Parameters in Practice (HSPIP). it can. In the case of a mixture composed of a plurality of substances, the HSP value of the mixture is calculated as the sum of values obtained by multiplying the HSP value of each substance as a component by the volume ratio of the component to the whole mixture. For HSP, see, for example, Hiroshi Yamamoto, S.H. Abbott, C.I. M.M. Reference can be made to Hansen, Chemical Industry, March 2010 issue.

In this specification, the Hansen solubility parameter (HSP) distance Ra between the dispersion material and the base material is expressed by the following formula:
_{^{Ra 2 = 4x (δd x -δd}} m) 2 + (δp x -δp m) 2 + (δh x -δh m) 2
[Where:
δd _x is a dispersion term of the Hansen solubility parameter (HSP) of the dispersion material,
δp _x is a polar term of the Hansen solubility parameter (HSP) of the dispersion,
δh _x is the hydrogen bond term of the Hansen solubility parameter (HSP) of the dispersion,
.delta.d _m is the variance terms of Hansen solubility parameters of the matrix (HSP),
.delta.p _m is a polar term of Hansen solubility parameters of the matrix (HSP),
δh _m is the hydrogen bond term of the Hansen solubility parameter (HSP) of the matrix,
Ra is the HSP distance between the dispersion material and the base material in the Hansen Solubility Parameter (HSP) space]
It is represented by

In the present specification, the Hansen solubility parameter (HSP) distance Rb between the dispersant and the solvent is expressed by the following formula:
_{^{Rb 2 = 4x (δd x -δd}} s) 2 + (δp x -δp s) 2 + (δh x -δh s) 2
[Where:
δd _x is a dispersion term of the Hansen solubility parameter (HSP) of the dispersion material,
δp _x is a polar term of the Hansen solubility parameter (HSP) of the dispersion,
δh _x is the hydrogen bond term of the Hansen solubility parameter (HSP) of the dispersion,
.delta.d _s is the variance terms of Hansen solubility parameters of the solvent (HSP),
.delta.p _s is the polar term Hansen parameter of the solvent (HSP),
δh _s is the hydrogen bond term of the Hansen solubility parameter (HSP) of the solvent,
Rb is the HSP distance between the dispersant and the solvent in the Hansen Solubility Parameter (HSP) space]
It is represented by Here, the solvent means a solvent of a solution containing composite particles to which a dispersing agent is added in the step (b).

  In the above formula (I), Ra-Rb is 3.0 or less, preferably 2.0 or less, more preferably 0 or less, from the viewpoint of promoting the composite of the base material and the dispersion material. Especially preferably, it is -2.0 or less. From the same viewpoint, Ra-Rb is -14.0 to 3.0, preferably -7.0 to 2.0, more preferably -5.0 to 0, and particularly preferably -3. 0.0 to -2.0.

Precursor of at least one element selected from Bi and Sb used in the step (a) and at least one element selected from Te and Se (hereinafter also referred to as base material constituent elements) The body is not particularly limited as long as it dissolves in a solvent, and specifically, salts of the above-mentioned base material constituent elements, preferably halides (for example, chloride, fluoride and bromide) of the above elements, sulfates, A nitrate etc. are mentioned, Especially preferably, a chloride, a sulfate, nitrate, etc. are mentioned. By adjusting the mass ratio of the base material constituent elements to be used, a base material of a desired material can be obtained. The base material of the thermoelectric conversion material obtained by the production method of the present invention is not particularly limited. For example, (Bi, Sb) ₂ Te ₃ system, (Bi, Sb) ₂ (Te, Se) ₃ system, Bi ₂ Te ₃ system, (Bi, Sb) Te system, Bi (Te, Se) system, etc. are mentioned. Among these, from the viewpoint of thermoelectric conversion efficiency, (Bi, Sb) ₂ (Te, Se) ₃ system and It is preferable to do. The HSP value of the base material can be calculated by preparing a plurality of solvents with known HSP values and using computer software (HSPiP) based on the test results of the dispersibility of the base material in each solvent. Those skilled in the art can select as appropriate.

  The reducing agent used in the step (a) is not particularly limited as long as it can reduce the precursor of the matrix constituent element. For example, tertiary phosphine, secondary phosphine and primary phosphine, hydrazine, Examples include hydrazine hydrate, hydroxyphenyl compound, hydrogen, hydride, borane, aldehyde, reductive halide, polyfunctional reductant, etc. Among them, alkali borohydride such as sodium borohydride, potassium borohydride 1 or more types of substances, such as lithium borohydride.

  The solvent for dissolving the precursor of the matrix constituent element used in the step (a) is not particularly limited as long as the precursor of the element can be dissolved. Specifically, methanol, ethanol, propanol, butanol , Pentanol, hexanol, heptanol and octanol may be selected from one or a mixture of two or more, and among these, it is desirable to use one having a high vapor pressure in the subsequent step (c). Therefore, ethanol and methanol are preferable.

  In the step (b), the solvent of the solution containing the composite particles obtained in the step (a) is optionally replaced with another solvent, and a dispersing agent is added to the solution. When the same solvent as used in step (a) is used in step (b), the solvent need not be replaced.

  As the solvent used in the step (b), the Hansen solubility parameter (HSP) distance Rb between the dispersion material and the solvent is the above formula (I) with respect to the Hansen solubility parameter (HSP) distance Ra between the dispersion material and the base material. ) Is not particularly limited as long as it satisfies the above), but water, alcohol having a linear or branched alkyl group, such as methanol, ethanol, 1-propanol, 2-propanol (isopropyl alcohol), n-propanol, isopropanol, 1- 1 selected from butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 1-hexanol, ethylene glycol, propanediol, hexanediol, aminoalcohol, and these A seed or a mixture of two or more. Among the, from the viewpoint of the dispersibility of the matrix particles, water, ethanol, methanol, isopropyl alcohol and mixtures thereof are preferred. The solvent has an HSP value of preferably 21.3 or more, more preferably 23.0 to 36.0, and particularly preferably 25.0 to 30.0, from the viewpoint of dispersibility of the base material particles. As described above, the HSP value of the solvent is registered or can be calculated from the chemical structure of the solvent by known means, and can be appropriately selected by those skilled in the art.

  The dispersion material is particularly limited as long as the Hansen solubility parameter (HSP) distance Ra between the dispersion material and the base material and the Hansen solubility parameter (HSP) distance Rb between the dispersion material and the solvent satisfy the above formula (I). For example, organic carbon compounds having siloxane and silmethylene as the main skeleton can be exemplified. In addition, as a dispersion material, an interface having a fine and complicated structure is formed between the base material and the dispersion material, and it is possible to combine with the constituent elements of the base material from the viewpoint of effectively scattering phonons due to an increase in the interface area. It is preferable to use a dispersant having a functional group. Here, the “functional group capable of binding to the base material constituent element” means a functional group that can be chemically bonded to the base material and maintain a strong bond. The functional group that can be bonded to the matrix constituent element is not particularly limited as long as it has the above-described connectivity with the matrix constituent element. For example, a mercapto group, a carboxyl group, an amino group, a vinyl group, an epoxy Group, styryl group, methacryl group, acryl group, isocyanurate group, ureido group, sulfide group and at least one selected from the group consisting of isocyanate groups. From the high versatility, mercapto group, amino group and It is preferably at least one selected from the group consisting of carboxyl groups. The HSP value of the dispersion material is calculated by preparing a plurality of solvents having known HSP values and using computer software (HSPiP) based on the results of the solubility test of each dispersion material in each solvent. Those skilled in the art can appropriately select them.

（式中、
Ｍは、Ｓｉ、Ｔｉ、Ａｌ、Ｓｂ及びＴｅからなる群より選択され、
Ｇ_１は独立して、母材構成元素と結合可能な官能基であり、
Ｇ_２は独立して、ＣＨ_３基、又は母材構成元素と結合可能な官能基であり、
ｎは、２〜７０の整数であり、
ｍは、０〜５の整数であり、
ｌは、０〜５の整数である）
で表される化合物が挙げられる。分散材として一般式（ＩＩ）で表される化合物を使用する場合、本発明の熱電変換材料において、分散材はＧ_１又はＧ_２において母材元素に結合している。一般式（ＩＩ）中のＧ_１及びＧ_２はそれぞれ同一であっても異なっていてもよい。このような構造を含む分散材は、上記一般式（ＩＩ）に示されるように官能基以外の最外側は反応性の少ない炭化水素基で構成されるために、加熱により重縮合して粗大粒子が生成することを防ぐことができる。このような観点から、上記一般式（ＩＩ）において、Ｇ_２がＣＨ_３基であることが好ましい。 Specific examples of the organic carbon-based compound having a functional group capable of binding to the base material constituent element include the following general formula (II):

(Where
M is selected from the group consisting of Si, Ti, Al, Sb and Te;
G ₁ is independently a functional group that can bind to the matrix constituent element;
G ₂ is independently a CH ₃ group, or a functional group that can be bonded to a matrix constituent element;
n is an integer of 2 to 70,
m is an integer of 0 to 5,
l is an integer of 0 to 5)
The compound represented by these is mentioned. When the compound represented by the general formula (II) is used as the dispersion material, in the thermoelectric conversion material of the present invention, the dispersion material is bonded to the base material element at G ₁ or G ₂ . G ₁ and G ₂ in the general formula (II) may be the same or different. As shown in the general formula (II), the dispersion material having such a structure is composed of a hydrocarbon group having a low reactivity on the outermost side other than the functional group. Can be prevented from being generated. From such a viewpoint, in the general formula (II), G ₂ is preferably a CH ₃ group.

  In one embodiment, n in the general formula (II) is an integer of 10 to 70, preferably 20 to 65, more preferably 30 to 60, from the viewpoint of affinity with the base material. Particularly preferred is 45 to 55. Moreover, the phonon thermal conductivity can be lowered by making the size of the dispersing material appropriate. In another embodiment, n in the general formula (II) is an integer of 2 to 70, preferably 2 to 60, and more preferably 2 to 45, from the viewpoint of affinity with the base material. is there.

  From the viewpoint of increasing the affinity with the base material, the dispersive material has a Hansen solubility parameter (HSP) distance Ra with the base material of preferably 13.0 or less, and more preferably 10.0 or less. From the same viewpoint, Ra is preferably 2.0 to 13.0, and more preferably 2.0 to 10.0.

  The dispersion material has a smaller affinity with the solvent than the affinity with the base material, and from the viewpoint of increasing the composite amount of the dispersion material and the base material, the Hansen solubility parameter (HSP) of the dispersion material and the solvent. ) The distance Rb is preferably 7.0 or more, and more preferably 10.0 or more. From the same viewpoint, Rb is preferably 7.0 to 26.0, and more preferably 10.0 to 15.0.

  In the above step (b), the dispersant used preferably has a small content from the viewpoint of suppressing a decrease in electrical conductivity, and specifically, preferably 1.0 to 40 mol based on the thermoelectric conversion material. %, More preferably 2.0 to 35 mol%, particularly preferably 4.0 to 20 mol%.

  In the step (c), the solution containing the composite particles and the dispersion material obtained in the step (b) is heat-treated and alloyed. Although the said heat processing will not be restrict | limited especially if alloying is possible, From the viewpoint of promoting alloying at low temperature, the method of carrying out a solvothermal reaction is preferable. The solvothermal reaction is a technique for obtaining a reaction product by reacting a plurality of raw materials in an organic solvent under high temperature and high pressure. The temperature for the solvothermal reaction is preferably 200 to 350 ° C. The pressure for the solvothermal reaction is preferably in the range of 0 to 20 MPa, more preferably in the range of 0.5 to 15 MPa. The time for the solvothermal reaction is preferably in the range of 1 to 48 hours, more preferably in the range of 5 to 24 hours, and still more preferably in the range of 8 to 12 hours. Means such as a reaction vessel and / or a reaction control device used for the solvothermal reaction are not particularly limited. In this step, an apparatus usually used for a solvothermal reaction in the technical field such as an autoclave can be used as a reaction vessel and a reaction control apparatus. For example, when the solvothermal reaction is performed at a temperature in the range of 200 to 250 ° C., an autoclave apparatus using a relatively inexpensive resin such as a fluororesin (eg, Teflon (registered trademark)) may be used. When the solvothermal reaction is performed at a temperature of 350 ° C. or lower, an autoclave apparatus using a heat-resistant / corrosion-resistant alloy such as a nickel alloy (for example, Hastelloy (registered trademark)) may be used. By using the above means, the solvothermal reaction of this step can be carried out without preparing a special apparatus. As an organic solvent used for the solvothermal reaction, for example, ethanol or methanol or a mixture thereof is preferable, and ethanol or methanol or a mixture thereof is preferable.

  After the step (c), the solution containing the alloyed particles is preferably dried. Examples of the drying method include an inert gas flow in a closed container.

  You may perform the sintering process (d) which sinters the thermoelectric conversion material containing a structural element after the said process (c). By this step, a thermoelectric conversion material in the form of a bulk body in which primary particles of the thermoelectric conversion material are aggregated can be formed. In this step, the means for sintering the thermoelectric conversion material is not particularly limited. For example, a sintering means usually used in the art such as a spark plasma sintering (SPS sintering) method or a hot press method can be applied. This step is preferably performed using an SPS sintering method. By sintering the primary particles of the thermoelectric conversion material by the above means, a thermoelectric conversion material in the form of a bulk body in which the primary particles are aggregated can be formed. For example, a thermoelectric conversion material bulk body can be obtained by performing SPS sintering (discharge plasma sintering) of a thermoelectric conversion material at 300 to 450 ° C. and 50 to 100 MPa for 10 to 30 minutes. SPS sintering can be performed using an SPS sintering machine equipped with a punch (upper part, lower part), an electrode (upper part, lower part), a die and a pressure device. Further, at the time of sintering, only the sintering chamber of the sintering machine may be isolated from the outside air to be an inert sintering atmosphere, or the entire system may be surrounded by a housing to be an inert atmosphere.

  The thermoelectric conversion material obtained by the production method of the present invention has a good lattice thermal conductivity because the composite amount of the base material and the dispersion material is sufficiently increased. Specifically, the lattice thermal conductivity of the thermoelectric conversion material obtained by the production method of the present invention is preferably 0.5 W / m / K or less, more preferably 0.25 W / m / K or less, particularly preferably 0. .15 W / m / K or less.

  The thermoelectric conversion material obtained by the production method of the present invention is usually in the form of fine particles and typically in the form of nanoparticles. In general, alloy particles having an average particle size greater than about 100 nm are classified as sub-microparticles, and alloy particles having an average particle size of about 100 nm or less are classified as nanoparticles. The thermoelectric conversion material usually has an average particle size of 300 nm or less, and typically has an average particle size of 200 nm or less. The thermoelectric conversion material usually has an average particle size of 50 nm or more, and typically has an average particle size of 70 nm or more. The thermoelectric conversion material of the present invention may be in the form of a bulk body obtained by sintering particles having a fine particle diameter (hereinafter also referred to as “primary particles”) having the above average particle diameter.

  The thermoelectric conversion material obtained by the manufacturing method of this invention can be used for manufacture of a thermoelectric conversion element. The thermoelectric conversion element assembles an N-type nanocomposite thermoelectric conversion material, a P-type nanocomposite thermoelectric conversion material, an electrode and an insulating substrate by a method known per se using the thermoelectric conversion material obtained by the production method of the present invention. Can be obtained. The thermoelectric conversion element assembles an N-type nanocomposite thermoelectric conversion material, a P-type nanocomposite thermoelectric conversion material, an electrode and an insulating substrate by a method known per se using the thermoelectric conversion material obtained by the production method of the present invention. Can be obtained.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to the range of an Example.
Examples 1-3 and Comparative Example 1
[I: Production of thermoelectric conversion material]
[Example 1]
(1) Contains a solution A containing a salt of element BiCl ₃ (0.24 g), SbCl ₃ (0.68 g), TeCl ₄ (1.51 g) and ethanol and a reducing agent (NaBH ₄ ) constituting the thermoelectric conversion material. Solution B (1.60 g of NaBH ₄ dissolved in 150 ml of ethanol) was mixed to prepare nano-base material composite particles constituting a thermoelectric conversion material.
(2) An organic carbon compound (0.14 g) shown in the following Table 1 and chemical formula is added as a dispersing agent in a solution containing the prepared nano matrix composite particles (Bi, Sb, Te) and the solvent shown in Table 1. did.
(3) Low-temperature heat treatment (solvothermal) (240 ° C., 48 hours) was performed to promote alloying and form a thermoelectric conversion material base material.
(4) The solvent was dried to obtain a powder.
(5) The alloy powder was bulked by a sintering process (360 ° C.) to obtain a sintered body.

[Example 2]
A sintered body was obtained in the same manner as in Example 1 except that the solvent used in the step (2) was changed to that shown in Table 1 below.

[Example 3]
A sintered body was obtained in the same manner as in Example 1 except that the solvent used in the step (2) was changed to that shown in Table 1 below.

[Comparative Example 1]
A sintered body was obtained in the same manner as in Example 1 except that the solvent used in the step (2) was changed to that shown in Table 1 below.

[II: Analysis]
For the sintered bodies of Example 1-3 and Comparative Example 1 obtained by the above procedure, the composition ratio was measured by ICP, and the composite amount was calculated.

<Measurement of elemental composition of sintered body>
It was measured by ICP analysis of the sintered body.
Device: ICPS-8000 manufactured by Shimadzu Corporation

[III: Results]
Table 1 shows the analysis results of the sintered bodies of Example 1-3 and Comparative Example 1.

  From the results in Table 1, it can be seen that the sintered body of Example 1-3 has a larger composite amount of the dispersion component (Si) than the sintered body of Comparative Example 1.

  The thermoelectric conversion element using the thermoelectric conversion material obtained by the production method of the present invention can be used for power generation using automobile exhaust heat or geothermal heat and a power source for artificial satellites. Moreover, the thermoelectric conversion element using the thermoelectric conversion material obtained by the manufacturing method of this invention can be utilized for temperature control elements, such as an electrical appliance and a motor vehicle.

Claims (2)

Next step:
(A) a solution containing a precursor of at least one matrix constituent element selected from Bi and Sb, a precursor of at least one matrix constituent element selected from Te and Se, and a solvent; A step of mixing a reducing agent to obtain matrix composite particles,
(B) The solvent of the solution containing the composite particles obtained in step (a) is optionally replaced with another solvent, and a dispersion material is added to the solution, and (c) obtained in step (b). A method for producing a thermoelectric conversion material comprising a step of heat-treating a solution containing composite particles and a dispersion material,
The Hansen solubility parameter (HSP) distance Ra between the dispersion material and the base material and the Hansen solubility parameter (HSP) distance Rb between the dispersion material and the solvent of the solution containing the composite particles to which the dispersion material is added are represented by the following formula (I):
Ra-Rb ≦ 3.0 (I)
Meet the,
The dispersion material has the following general formula (II):

(Where
M is selected from the group consisting of Si, Ti, Al, Sb and Te;
G ₁ is independently a functional group that can bind to the matrix constituent element;
G ₂ is independently a CH ₃ group, or a functional group that can be bonded to a matrix constituent element;
n is an integer of 45 to 55;
m is an integer of 0 to 5,
l is an integer of 0 to 5)
The above method, which is a compound represented by the formula:   The method according to claim 1, wherein the solubility parameter (SP) value of the solvent Hildebrand is 21.3 or more.

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