JP2021097177A - Thermoelectric element and manufacturing method thereof - Google Patents

Abstract

To provide a Mg2Si-based thermoelectric element and a manufacturing method thereof with high thermoelectric performance and high thermal stability.SOLUTION: Boron (B) is added as an additive element before sintering a Mg2Si thermoelectric material. For example, in a weighing step S1, when magnesium powder and silicon powder as main raw materials and boron powder as an additive element are weighed, weighing is performed such that the amount of boron becomes a predetermined amount (for example, 0.25 at% or more) with respect to a certain amount of magnesium silicide (Mg2Si). Raw material powder is uniformly mixed in a mixing step S2, and pressure-molded in a molding step S3 to prepare a molded product for synthesis, and heat treatment is performed in a synthesis step S4 to synthesize a Mg2Si thermoelectric material. In a crushing step S5, the synthesized Mg2Si thermoelectric material is crushed, and in a sintering step S6, the crushed Mg2Si thermoelectric material is sintered.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thermoelectric element and a method for manufacturing the same, and more particularly to an Mg ₂ Si based thermoelectric element and a method for manufacturing the same.

_{Conventionally, Mg 2} Si-based thermoelectric materials having improved thermoelectric characteristics by containing various dopants in magnesium VDD (Mg _{2 Si) have been known, and thermoelectric elements using such Mg 2} Si-based thermoelectric materials have been known. Is known to have relatively high thermoelectric performance (power generation performance).

However, it is known that the conventional Mg ₂ Si thermoelectric element gradually deteriorates in its thermoelectric characteristics when it is used for power generation, that is, when it is used for a long time with a temperature difference applied to both ends of the element. , Did not have sufficient thermal durability.

In Japanese Patent Application Laid-Open No. 2011-29632, a magnesium-silicon composite material having a dimensionless performance index of 0.665 or more at 866K and substantially containing no dopant, and a dopant having an atomic weight ratio of 0.10 to 0 A magnesium-silicon composite material containing 2.00 at% is disclosed, and it is described that when Sb is contained as a dopant, a thermoelectric conversion material having excellent durability at high temperatures can be obtained.

Japanese Unexamined Patent Publication No. 2011-29632

An object of the present invention is to provide an Mg ₂ Si thermoelectric element having high thermoelectric performance and high thermal stability, and a method for manufacturing the same.

The thermoelectric element according to the present invention is a thermoelectric element composed of magnesium silicide, and contains boron as an additive element, and the boron is dispersed and exists.

In this case, the boron may be present in the grain boundary region of magnesium silicide.

Further, in the above case, a compound of magnesium and boron may be formed around the boron.

The method for producing a thermoelectric element according to the present invention includes _{a boron addition step of adding boron as an additive element to a raw material used for synthesizing an Mg 2} Si thermoelectric material, and a raw material to which boron is added in the boron addition step. On the other hand, it is characterized by including a synthesis step of synthesizing an _{Mg 2} Si thermoelectric material by performing heat treatment and a sintering step of sintering _{the Mg 2 Si thermoelectric material synthesized in the synthesis step.}

In this case, the raw materials may be magnesium and silicon.

Also, another method for manufacturing a thermoelectric device according to the present invention comprises a synthesis step of synthesizing Mg ₂ Si-based thermoelectric material, the Mg ₂ Si based thermoelectric materials synthesized in the synthesizing step, adding boron as an additive element It is characterized by including a boron addition step and a sintering step of sintering an _{Mg 2 Si thermoelectric material to which boron has been added in the boron addition step.}

In the above case, _{a molding step of pressure molding the raw material used for synthesizing the Mg 2} Si thermoelectric material is further provided, and the synthesis step heat-treats the synthetic molded product molded in the molding step. This may be carried out _{to synthesize an Mg 2} Si based thermoelectric material.

The manufacturing method of yet another thermoelectric element according to the present invention includes the steps of preparing a Mg ₂ Si-based thermoelectric material, and boron added step of adding boron as an additional element to the Mg ₂ Si based thermoelectric material, the boron It is characterized by including a sintering step of sintering an _{Mg 2} Si thermoelectric material to which boron is added in the addition step.

In the above case, in the boron addition step, 0.25 at% or more of boron may be added to a predetermined amount of magnesium silicide.

According to the present invention, it is possible to provide a thermoelectric element having high thermoelectric performance and high thermal stability.

It is a figure for demonstrating the manufacturing method of the thermoelectric element by 1st Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the thermoelectric element by the 2nd Embodiment of this invention. It is a table which shows the evaluation result of each thermoelectric element. It is a table which shows the evaluation result of thermal durability. It is a scanning electron micrograph (drawing substitute photograph) of the surface of Example 4. FIG. It is a scanning electron micrograph and an EDX mapping image (drawing substitute photograph) which enlarged the periphery of a boron particle. It is a figure which shows the Raman spectrum of an observation area.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The method for manufacturing a thermoelectric element according to the present invention is for manufacturing an Mg ₂ Si thermoelectric element, in which boron (B) is added as an additive element before sintering of _{the Mg 2 Si thermoelectric material.}

Hereinafter, as an embodiment of the method for manufacturing a thermoelectric element according to the present invention, two cases where the timing of adding boron is different will be described. That is, it is added before the step of synthesizing the _{Mg 2 Si thermoelectric material (first embodiment) and after the step of synthesizing the Mg 2} Si thermoelectric material (and before the sintering step). The thing (second embodiment) will be described.

<< First Embodiment >>
FIG. 1 is a diagram for explaining a method for manufacturing a thermoelectric element according to the first embodiment of the present invention. In the present embodiment, boron as an additive element is added in the first weighing step.

As shown in the figure, first, the raw materials are weighed (S1). For example, magnesium (Mg) powder and silicon (Si) powder, which are the main raw materials, and boron (B) powder, which is an additive element, are weighed. At this time, weighing is performed so that the amount of boron is a predetermined amount (for example, 0.25 at% or more) with respect to a certain amount of magnesium silicide (Mg _{2 Si).} At this time, magnesium may be excessively charged in consideration of the amount of evaporation in the manufacturing process.

Next, the raw material powders are mixed so that the raw material powders weighed in the weighing step S1 become uniform (S2). For example, the raw material powder is mixed using a mixer or the like.

Next, a synthetic molded product is produced by pressure molding the raw material powder uniformly mixed in the mixing step S2 (S3). For example, a molded product for synthesis is produced by performing cold uniaxial press working at an appropriate surface pressure (for example, about 20 MPa).

_{Next, the Mg 2} Si thermoelectric material is synthesized by heat-treating the synthetic molded product produced in the molding step S3 (S4). For example, the synthetic molded product is housed in a semi-sealable container (for example, a carbon container) and then placed in an electric furnace in an argon (Ar) atmosphere at 650 ° C to 800 ° C (for example, 700 ° C). ) Is kept at the temperature of 1 to 4 hours _{to synthesize Mg 2} Si thermoelectric material.

_{Next, the Mg 2} Si thermoelectric material synthesized in the synthesis step S4 is pulverized (S5). For example, it is crushed to a desired particle size (for example, 38 μm or less) by an automatic mortar, a ball mill, or the like.

_{Next, the Mg 2} Si thermoelectric material crushed in the crushing step S5 is sintered (S6). For example, pressure sintering is performed by the discharge plasma sintering method (SPS).

The thermoelectric element manufactured through the above steps S1 to S6 is processed into a desired shape and used as needed.

<< Second Embodiment >>
FIG. 2 is a diagram for explaining a method for manufacturing a thermoelectric element according to the second embodiment of the present invention. In this embodiment, boron as an additive element is added in the step after the synthesis _{of the Mg 2 Si thermoelectric material.}

As shown in the figure, first, the raw materials are weighed (S11). For example, magnesium (Mg) powder and silicon (Si) powder, which are raw materials, are weighed. At this time, magnesium may be excessively charged in consideration of the amount of evaporation in the manufacturing process.

Next, the raw material powders are mixed so that the raw material powders weighed in the weighing step S11 are uniform (S12). For example, the raw material powder is mixed using a mixer or the like.

Next, a synthetic molded product is produced by pressure molding the raw material powder uniformly mixed in the mixing step S12 (S13). For example, a molded product for synthesis is produced by performing cold uniaxial press working at an appropriate surface pressure (for example, about 20 MPa).

_{Next, the Mg 2} Si thermoelectric material is synthesized by heat-treating the synthetic molded product produced in the molding step S13 (S14). For example, the synthetic molded product is housed in a semi-sealable container (for example, a carbon container) and then placed in an electric furnace in an argon (Ar) atmosphere at 650 ° C. to 800 ° C. (for example, 700 ° C.). ) Is kept at the temperature of 1 to 4 hours _{to synthesize Mg 2} Si thermoelectric material.

_{Next, the Mg 2} Si thermoelectric material synthesized in the synthesis step S14 is pulverized (S15). For example, it is crushed to a desired particle size (for example, 38 μm or less) by an automatic mortar, a ball mill, or the like.

Next, boron (B) is added as an additive element _{to the Mg 2} Si thermoelectric material pulverized in the pulverization step S15 (S16). For example, the crushed Mg ₂ Si thermoelectric material and boron powder as an additive element are weighed, and a predetermined amount (for example, 0.25 at%) is applied to a _{fixed amount of Mg 2 Si thermoelectric material.} The above) boron is added.

_{Next, the Mg 2} Si thermoelectric material powder to which boron is added _{is mixed so that the Mg 2} Si thermoelectric material powder to which boron is added becomes uniform in the boron addition step S16 (S17). For example, a mixer or the like is used to mix the Mg ₂ Si thermoelectric material powder to which boron has been added.

_{Next, the Mg 2} Si thermoelectric material uniformly mixed in the mixing step S17 is sintered (S18). For example, pressure sintering is performed by the discharge plasma sintering method (SPS).

The thermoelectric element manufactured through the above steps S11 to S18 is processed into a desired shape and used as needed.

In the production method of the above-mentioned thermoelectric elements, before sintering of the Mg ₂ Si based thermoelectric material, more specifically, before the synthesis of the Mg ₂ Si based thermoelectric material, or after synthesis of the Mg ₂ Si based thermoelectric material (, Moreover, by adding boron as an additive element before sintering), a thermoelectric element having high thermoelectric performance and high thermal stability can be obtained.

Although the embodiments of the present invention have been described above, as a matter of course, the embodiments of the present invention are not limited to those described above. For example, in the above-described embodiment, the Mg ₂ Si thermoelectric material is synthesized from the raw material, but boron is added as an additive element _{to the separately prepared Mg 2 Si thermoelectric material to generate boron.} It is also conceivable to sinter the _{added Mg 2 Si thermoelectric material.}

Next, an example of the method for manufacturing a thermoelectric element according to the present invention will be described.

First, as described below, a plurality of types of thermoelectric elements composed of magnesium silicide to which boron was added as an additive element were produced by changing the amount of boron to be added and the timing of addition.

<< Example 1 >>
First, magnesium (Mg) powder with a purity of 99.5% and a particle size of 180 μm (manufactured by High Purity Chemical Laboratory Co., Ltd.) has a purity of 99.9 so that the chemical ratio is (Mg _2.02 Si ₁ ) B _0.25. %, Silicon (Si) powder with a particle size of 150 μm (manufactured by High Purity Chemical Laboratory Co., Ltd.) and boron (B) powder with a purity of 99% and particle size 45 μm (manufactured by High Purity Chemical Laboratory Co., Ltd.) are weighed. went. That is, weighing was performed so that 0.25 at% of boron (B) was contained in a fixed amount (30 g) of Mg _2.02 Si _1. Specifically, the magnesium powder weighed 19.083 g, the silicon powder weighed 10.916 g, and the boron powder weighed 0.011 g. Here, in consideration of the amount of evaporation in the manufacturing process, magnesium is excessively charged (the same applies to each of the following examples).

Next, after mixing the raw material powder in a mortar so that the raw material powder becomes uniform, the raw material powder is housed in a 30φ super steel die, and the pressure is 20 MPa by a press machine (NT-50H manufactured by NPA System Co., Ltd.). Pressing was performed with pressure to obtain a cylindrical synthetic molded product having a size of 30φ × 5 mm.

Next, the obtained synthetic molded material was housed in a semi-sealable carbon container with a lid, placed in an electric furnace, and heat-treated in an argon atmosphere at a temperature of 700 ° C. for 1 hour. Aggregates of Mg ₂ Si thermoelectric material were obtained.

Next, the obtained aggregates were roughly pulverized in a mortar to 1 mm or less, and then finely pulverized in an automatic mortar so that the particle size was 38 μm or less.

Next, the obtained Mg ₂ Si-based thermoelectric material powder was filled in a 30φ carbon die for discharge plasma sintering, and then placed in a discharge plasma sintering apparatus to have a sintering atmosphere of 4 × 10 ^-4. Sintering was performed in the vacuum of 850 ° C., a sintering pressure of 30 MPa, and a sintering time of 10 minutes to obtain a thermoelectric element (sintered body).

<< Example 2 >>
First, the magnesium (Mg) powder, the silicon (Si) powder, and the boron (B) powder were weighed so that the stoichiometric ratio was (Mg _2.02 Si ₁ ) B _0.75. That is, weighing was performed so that 0.75 at% of boron (B) was contained in a fixed amount (30 g) of Mg _2.02 Si _1. Specifically, the magnesium powder weighed 19.083 g, the silicon powder weighed 10.916 g, and the boron powder weighed 0.032 g.

Hereinafter, a thermoelectric element was produced in the same manner as in Example 1 described above.

<< Example 3 >>
First, the magnesium (Mg) powder and the silicon (Si) powder were weighed so that the stoichiometric ratio was Mg _2.02 Si _{1 and the total mass was 30 g.}

Next, after mixing the raw material powder in a mortar so that the raw material powder becomes uniform, the raw material powder is housed in a 30φ super steel die and pressed by the above press machine at a pressure of 20 MPa to obtain 30φ × 5 mm. A cylindrical synthetic molded product was obtained.

Next, the obtained synthetic molded body was housed in a semi-sealable carbon container with a lid, placed in an electric furnace, and heat-treated in an argon atmosphere at a temperature of 700 ° C. for 1 hour. Aggregates of Mg ₂ Si were obtained.

Next, the obtained aggregates were roughly pulverized in a mortar to 1 mm or less, and then finely pulverized in an automatic mortar so that the particle size was 38 μm or less.

Next, a certain amount of Mg ₂ Si powder obtained for (3.5 g), as boron (B) is contained 0.25 at%, Mg ₂ Si powder obtained, and, the boron (B ) The powder was weighed. Specifically, the Mg ₂ Si powder was weighed to 3.5 g and the boron powder was weighed to 0.0012 g.

_{Next, the weighed Mg 2} Si powder and boron powder are mixed in a dairy pot so as to be uniform, filled in a 30φ carbon die for discharge plasma sintering, and placed in a discharge plasma sintering device. Then, sintering was performed in ^{a vacuum of a sintering atmosphere of 4 × 10 -4} under the conditions of a sintering temperature of 850 ° C., a sintering pressure of 30 MPa, and a sintering time of 10 minutes to obtain a thermoelectric element (sintered body).

<< Example 4 >>

First, in the same manner as in Example 3 described above, Mg ₂ Si powder was obtained, and then boron (B) was 0.75 at% based on a certain amount (3.5 g) _{of the obtained Mg 2 Si powder. The obtained Mg 2} Si powder and the above-mentioned boron (B) powder were weighed so as to be contained. Specifically, the Mg ₂ Si powder was weighed to 3.5 g and the boron powder was weighed to 0.0037 g.

Hereinafter, a thermoelectric element was produced in the same manner as in Example 3 described above.

<< Example 5 >>
First, the magnesium (Mg) powder, the silicon (Si) powder, and the boron (B) powder were weighed so that the stoichiometric ratio was (Mg _2.02 Si ₁ ) B _{1. That is, weighing was performed so that 1} at% of boron (B) was contained in a fixed amount (30 g) of Mg _2.02 Si 1. Specifically, the magnesium powder weighed 19.083 g, the silicon powder weighed 10.916 g, and the boron powder weighed 0.043 g.

Hereinafter, a thermoelectric element was produced in the same manner as in Example 1 described above.

<< Example 6 >>

First, in the same manner as in Example 3 described above, Mg ₂ Si powder is obtained, and then 1 at% of boron (B) is contained in a certain amount (3.5 g) _{of the obtained Mg 2 Si powder.} As described above, the obtained Mg ₂ Si powder and the above-mentioned boron (B) powder were weighed. Specifically, the Mg ₂ Si powder was weighed to 3.5 g and the boron powder was weighed to 0.0049 g.

Hereinafter, a thermoelectric element was produced in the same manner as in Example 3 described above.

Further, as described below, a thermoelectric element composed of magnesium silicide to which boron was not added was produced.

<< Comparative Example 1 >>
First, the magnesium (Mg) powder and the silicon (Si) powder were weighed so that the stoichiometric ratio was Mg _2.02 Si _{1 and the total mass was 30 g.}

Hereinafter, a thermoelectric element was produced in the same manner as in Example 1 described above.

Further, as described below, a plurality of types of thermoelectric elements having different production conditions (heat treatment time and sintering time) in the synthesis step and the sintering step from Examples 1 to 6 were produced.

<< Modification 1 >>
A thermoelectric element was produced in the same manner as in Example 3 described above, except that the heat treatment time in the synthesis step was 4 hours and the sintering time in the sintering step was 45 minutes.

<< Modification 2 >>
A thermoelectric element was produced in the same manner as in Example 4 described above, except that the heat treatment time in the synthesis step was 4 hours and the sintering time in the sintering step was 45 minutes.

Further, as described below, a thermoelectric element composed of magnesium silicide to which boron was not added was produced.

<< Comparative Example 2 >>
A thermoelectric element was produced in the same manner as in Comparative Example 1 described above, except that the heat treatment time in the synthesis step was 4 hours and the sintering time in the sintering step was 45 minutes.

Next, each thermoelectric element was evaluated at room temperature (25 ° C.) as follows.

First, while heating one end of each thermoelectric element with a heater, the temperature difference between both ends of each thermoelectric element and the output voltage were measured, and the Seebeck coefficient was calculated based on the measurement result. In addition, the specific resistance was measured by the 4-probe method. Furthermore, the power factor (output factor) was calculated based on the obtained Seebeck coefficient and specific resistance.

FIG. 3 is a table showing the evaluation results of each thermoelectric element. In the figure, α represents the Seebeck coefficient (unit: μV / K), ρ represents the specific resistance (unit: μΩm), and PF represents the power factor (unit: W / mK ² ).

First, focusing on the Seebeck coefficient α, as shown in the figure, all of Examples 1 to 6, Modified Examples 1 and 2 and Comparative Examples 1 and 2 have negative values, and n-type thermoelectrics. It can be seen that it is an element (n-type semiconductor element).

Further, in comparison with Comparative Example 1, all of Examples 1 to 6 have a Seebeck coefficient α of the same degree or smaller (larger absolute value) and a lower specific resistance ρ, and are relative to each other. High thermoelectric performance (power factor) is obtained.

From the above, by adding a certain amount (for example, 0.25 at% or more) of boron as an additive element to a certain amount of magnesium silicide, a thermoelectric element having high thermoelectric performance (power factor) can be obtained. It turns out that it can be done.

Further, in comparison with the modified examples 1 and 2, all of the examples 1 to 6 have a smaller (larger absolute value) Seebeck coefficient α and a lower specific resistance ρ, and are relative to each other. High thermoelectric performance (power factor) is obtained. That is, with respect to the heat treatment time and the sintering time, the shorter the heat treatment time and the sintering time, the higher the thermoelectric performance (power factor) is obtained. This is due to the fact that when heat treatment or sintering treatment is performed for a longer period of time, magnesium in the raw material is oxidized even in a high vacuum to form (more) magnesium oxide. Conceivable.

Further, with respect to Examples 3 and 4 and Modified Example 2, the thermal durability was evaluated as follows.

First, each thermoelectric element was placed in an electric furnace and heat-treated in the air at a temperature of 400 ° C. for a certain period of time (512 hours and 1024 hours). Then, after naturally cooling to room temperature, the Seebeck coefficient was calculated and the specific resistance was measured by the same method as described above.

FIG. 4 is a table showing the evaluation results of thermal durability. In the figure, α represents the Seebeck coefficient (unit: μV / K), and ρ represents the specific resistance (unit: μΩm).

As shown in the figure, even when heat-treated at 400 ° C. in the atmosphere for 1000 hours or more, neither the Seebeck coefficient nor the specific resistance showed a large change and had stable thermoelectric characteristics. I was able to confirm that it was there.

Further, the surface of Example 4 was observed and elemental analysis was performed using a scanning electron microscope (SEM) and an energy dispersive X-ray analyzer (EDX) (TM3030Plus, manufactured by Hitachi High-Technologies Corporation).

FIG. 5 is a scanning electron micrograph of the surface of Example 4, and FIG. 6 is a scanning electron micrograph and an EDX mapping image obtained by enlarging a part of FIG. 5 (around the black spot).

In FIG. 5, the black spots correspond to boron. As shown in the figure, it can be confirmed that the added boron has no segregation and is dispersed over the entire surface.

Further, the cleaved surface of Example 4 was etched with a 1% dilute ethanol solution of hydrochloric acid for about 10 seconds to neutralize it, and then observed by SEM. When the interface of each magnesium silicide particle was searched by SEM, it was confirmed that the boron particle was present in the grain boundary region (microcrack) of the magnesium silicide particle.

It is considered that a part of the added boron invades the body-centered position (4b site) of magnesium silicide instead of the grain boundary region of magnesium silicide. As described above, the boron-added ones (Examples 1 to 6) show higher thermoelectric performance than the boron-free ones (Comparative Example 1), which is the result of the added boron. It can be considered that a part of it is caused by invading the body-centered position of magnesium silicide.

Further, from the EDX mapping image shown in FIG. 6, it was confirmed that both magnesium and boron are present around the dispersed boron particles (the boundary region between magnesium silicide and boron).

Therefore, further, using a laser Raman microscope (RAMANtouch, manufactured by Nanophoton Corporation), the region (observation region) in which both magnesium and boron are present around the boron particles of Example 4 was observed.

FIG. 7 is a diagram showing a Raman spectrum in the observation region. As shown in the figure, boride magnesium (Mg ₃ B ₂₎ and the peak corresponding can be confirmed in magnesium diboride (MgB _2), the observation region (around the boron particles), boron compound (boride magnesium And magnesium diboride) was confirmed to be produced.

It is considered that this compound phase was formed by re-reacting with magnesium which evaporates by a certain amount during sintering. Comparing oxygen and boron, boron is relatively more likely to bind to magnesium. Therefore, the added boron binds to magnesium first to form a boron compound, thereby forming a sintered body. It is considered that the formation of magnesium oxide in the film was suppressed, and as a result, the thermal stability was not lowered due to magnesium oxide, and high thermal stability was obtained as described above.

S1, S11 Weighing process S2, S12 Mixing process S3, S13 Molding process S4, S14 Synthesis process S5, S15 Crushing process S6, S18 Sintering process S16 Boron addition process S17 Mixing process

Claims (9)

A thermoelectric element composed of magnesium silicide.
A thermoelectric device containing boron as an additive element, and the boron is dispersed and present. The thermoelectric device according to claim 1, wherein the boron is present in the grain boundary region of magnesium silicide. The thermoelectric device according to claim 1 or 2, wherein a compound of magnesium and boron is formed around the boron. A boron addition process in which boron is added as an additive element to the raw materials used in the synthesis of Mg _{2 Si thermoelectric materials.}
In the boron addition step, the raw material to which boron is added is heat-treated _{to synthesize an Mg 2} Si thermoelectric material, and a synthesis step.
A method for manufacturing a thermoelectric element, which comprises a sintering step for sintering an _{Mg 2} Si thermoelectric material synthesized in the synthesis step. The method for manufacturing a thermoelectric element according to claim 4, wherein the raw materials are magnesium and silicon. Synthesis process for synthesizing Mg _{2 Si thermoelectric materials and}
A boron addition step of adding boron as an additive element _{to the Mg 2} Si thermoelectric material synthesized in the synthesis step, and a boron addition step.
A method for manufacturing a thermoelectric element, which comprises a sintering step of sintering an _{Mg 2} Si thermoelectric material to which boron is added in the boron addition step. Further equipped with a molding process for pressure molding the raw materials used for the synthesis of Mg _{2 Si thermoelectric materials.}
The synthesis step according to any one of claims 4 to 6, wherein the synthetic molded product molded in the molding step is heat-treated to synthesize an Mg _{2 Si thermoelectric material.} Manufacturing method of thermoelectric element. The _{process of preparing Mg 2} Si thermoelectric material and
A boron addition step of adding boron as an additive element to the Mg _{2 Si thermoelectric material, and}
A method for manufacturing a thermoelectric element, which comprises a sintering step of sintering an _{Mg 2} Si thermoelectric material to which boron is added in the boron addition step. The production of the thermoelectric element according to any one of claims 4 to 8, wherein the boron addition step adds 0.25 at% or more of boron to a predetermined amount of magnesium silicide. Method.

Images