SILICIDE ALLOY MATERIAL AND THERMOELECTRIC CONVERSION DEVICE IN WHICH SAME IS USED

Abstract

Provided is a silicide-based alloy material with which environmental load can be reduced and high thermoelectric conversion performance can be obtained.

Provided is a silicide-based alloy material including silicon and ruthenium as main components, in which when the contents of silicon and ruthenium are denoted by Si and Ru, respectively, the atomic ratio of the devices constituting the alloy material satisfies the following:

45 atm %≤Si/(Ru+Si)≤70 atm %

30 atm %≤Ru/(Ru+Si)≤55 atm %.

Claims

1. A silicide-based alloy material comprising silicon and ruthenium as main components, wherein when contents of silicon and ruthenium are denoted by Si and Ru, respectively, an atomic ratio of devices constituting the alloy material satisfies the following:
45 atm %≤Si/(Ru+Si)≤70 atm %
30 atm %≤Ru/(Ru+Si)≤55 atm %

2. The silicide-based alloy material according to claim 1, wherein an average crystal grain size of the silicide-based alloy material is 50 μm or less.

3. The silicide-based alloy material according to claim 2, wherein the average crystal grain size of the silicide-based alloy material is 1 nm to 20 μm.

4. The silicide-based alloy material according to claim 3, wherein the average crystal grain size of the silicide-based alloy material is 3 nm to 1 μm.

5. The silicide-based alloy material according to claim 4, wherein the average crystal grain size of the silicide-based alloy material is 5 nm to 500 nm.

6. The silicide-based alloy material according to claim 1, wherein the silicide-based alloy material has a plurality of crystal phases in a texture.

7. The silicide-based alloy material according to claim 1, wherein the contents of silicon and ruthenium satisfy the following:
55 atm %≤Si/(Ru+Si)≤65 atm %
35 atm %≤Ru/(Ru+Si)≤45 atm %.

8. The silicide-based alloy material according to claim 1, wherein the silicide-based alloy material has at least two or more kinds of crystal phases selected from space groups 198, 64, and 60 in the texture.

9. The silicide-based alloy material according to claim 1, wherein the contents of silicon and ruthenium satisfy the following:
47 atm %≤Si/(Ru+Si)≤60 atm %
40 atm %≤Ru/(Ru+Si)≤53 atm %.

10. The silicide-based alloy material according to claim 1, wherein the silicide-based alloy material has crystal phases with space groups 221 and 198 in a texture.

11. A thermoelectric conversion device, comprising: the silicide-based alloy material of claim 1.

Description

EXAMPLES

[0067] Hereinafter, Examples of the present invention will be described; however, the present invention is not intended to be limited to these.

[0068] (Method for Measuring Average Crystal Grain Size)

[0069] Measurement was made using an electrolytic emission type operation electron microscope JSM-7100F (manufactured by JEOL, Ltd.) with EBSP.

[0070] (Method for Measuring Crystal Phase)

[0071] Identification of crystal phases was carried out from the diffraction peaks obtained by X-ray diffraction measurement.

[0072] (Method for Measuring Composition)

[0073] Quantitative determination was carried out by an ICP-MS mass analysis method.

[0074] (Method for Measuring Electrical Characteristics)

[0075] Measurement was made using a Hall effect analyzer (ResiTest 8400 manufactured by Toyo Corporation).

[0076] (Method for Measuring Seebeck Coefficient)

[0077] A Seebeck coefficient measurement system (option for ResiTest 8400 manufactured by Toyo Corporation) was attached to the above-described Hall effect analyzer, and measurement was carried out.

[0078] (Method for Measuring Thermal Conductivity)

[0079] Measurement was carried out using a laser flash method thermal conduction analyzer (LFA-457 manufactured by NETZSCH Group).

Example 1

[0080] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=60 atm % and Ru/(Ru+Si)=40 atm %, and then the mixture was filled into a water-cooled mold and was subjected to arc melting. The raw material lump thus obtained was pulverized in an agate mortar using a mortar, and a powder was produced. The obtained powder was filled into a rectangle-shaped hot press mold having a size of 30 mm×15 mm, and hot pressing was performed. The hot press conditions were set to a rate of temperature increase of 200° C./hour, the powder was maintained for 1 hour at a calcination temperature of 1400° C., and the pressure was set to 2.3 ton. Furthermore, the degree of vacuum was 1.0e-2 Pa. During sintering, a REFERTHERMO (type L) installed near the alloy sample showed 1250° C.

[0081] As a result of EBSD measurement, regarding the obtained alloy sample, a crystal phase (space group 60) of Ru.sub.2Si.sub.3 mixed with about 0.001% of Si phase in terms of area ratio was observed.

[0082] Assuming that the alloy sample was pure Ru.sub.2Si.sub.3, the relative density of the obtained alloy sample was calculated to be 91.2% by the Archimedes method, using the theoretical density of Ru.sub.2Si.sub.3 of 6.79 g/cm.sup.3.

[0083] Subsequently, the alloy sample was processed into a size of 10 mm×10 mm×1 mm t to obtain a sample for electrical characteristics measurement, the alloy sample was processed into a size of 10 mm×2 mm t to obtain a sample for thermal conductivity measurement, and the respective samples were subjected to measurement. The measurement conditions were set to 600° C. and vacuum conditions for the Seebeck coefficient and electrical resistance. On the other hand, the thermal conductivity was measured under two conditions of room temperature in a nitrogen atmosphere, and 600° C. in an Ar atmosphere. The respective measurement results are shown in Table 1.

Example 2

[0084] The hot press conditions were set to a calcination temperature of 1750° C., and for the other conditions, the experiment was carried out under conditions similar to those of Example 1.

Example 3

[0085] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=61 atm % and Ru/(Ru+Si)=39 atm %, the hot press conditions were set to a calcination temperature of 1750° C. and a pressing pressure of 1.1 ton, and for the other conditions, the experiment was carried out under conditions similar to those of Example 1.

Example 4

[0086] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=61 atm % and Ru/(Ru+Si)=39 atm %, the hot press conditions were set to a calcination temperature of 1750° C. and a pressing pressure of 1.1 ton, and for the other conditions, the experiment was carried out under conditions similar to those of Example 1.

Example 5

[0087] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=61 atm % and Ru/(Ru+Si)=39 atm %, the hot press conditions were set to a calcination temperature of 1750° C. and a pressing pressure of 0.5 ton, and for the other conditions, the experiment was carried out under conditions similar to those of Example 1.

TABLE-US-00001 TABLE 1 Area- Space Thermal Average weighted group of conductivity Composition crystal average observed Electrical Seebeck Power (W/K .Math. m) Si/(Si + Ru) Ru/(Si + Ru) grain crystal grain crystal resistance coefficient factor Room at % at % size (m) size (m) phase (Ω .Math. cm) (μV/K) (W/mK.sup.2) temperature 600° C. Example 1 60 40 2.10E−06 4.10E−06 60, 198 4.20E−02 322 2.47E−04 4.0 1.6 Example 2 60 40 3.00E−06 2.70E−05 60, 198 1.20E−02 315 8.27E−04 4.6 2.8 Example 3 61 39 2.20E−06 1.02E−05 60, 198 1.70E−02 310 5.65E−04 4.6 3.0 Example 4 58.8 41.2 3.20E−06 2.80E−05 60, 198 5.90E−03 144 3.51E−04 4.9 3.1 Example 5 60 40 1.30E−05 6.20E−05 60 4.10E−02 350 2.99E−04 6.0 4.1

[0088] The obtained results of Examples 1 to 5 showed values lower than the thermal conductivity 5 W/K.Math.m described in Non Patent Literatures 1 and 2 even at 600° C. From this, it is possible to achieve high thermoelectric conversion performance even at 600° C. by controlling the textural particle size of the alloy to be finer.

Example 6

[0089] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=50 atm % and Ru/(Ru+Si)=50 atm %, and then the mixture was filled into a water-cooled mold and was subjected to arc melting. The raw material lump thus obtained was pulverized in an agate mortar using a mortar, and a powder was produced. The obtained powder was filled into a rectangle-shaped hot press mold having a size of 30 mm×15 mm, and hot pressing was performed. The hot press conditions were set to a rate of temperature increase of 200° C./hour, the powder was maintained for 1 hour at a retention temperature of 1400° C., and the pressure was set to 2.3 ton. Furthermore, the degree of vacuum was 1.0e-2 Pa. During sintering, a REFERTHERMO (type L) installed near the alloy sample showed 1250° C.

[0090] As a result of EBSD measurement, it was found that the obtained alloy sample had a textural structure of RuSi in which a crystal phase (phase 1) with space group 221 and a crystal phase (phase 2) with space group 198 were included at proportions resulting in an area ratio (phase 1/(phase 1+phase 2))=0.005.

[0091] Regarding the relative density of the obtained alloy sample, assuming that the alloy sample had a true density, which was an arithmetic mean of the respective theoretical densities of phase 1 and phase 2 of RuSi, 8.44 g/cm.sup.3 and 8.04 g/cm.sup.3, the relative density was calculated to be 95.0% by the Archimedes method.

[0092] Subsequently, the alloy sample was processed into a size of 10 mm×10 mm×1 mm t to obtain a sample for electrical characteristics measurement, the alloy sample was processed into a size of 10 mm×2 mm t to obtain a sample for thermal conductivity measurement, and the respective samples were subjected to measurement. The measurement conditions were set to 100° C. and vacuum conditions for the Seebeck coefficient and electrical resistance. On the other hand, the thermal conductivity was measured under two conditions of room temperature in a nitrogen atmosphere, and 100° C. in an Ar atmosphere. The respective measurement results are shown in Table 2.

Example 7

[0093] The hot press conditions were set to a retention temperature of 1750° C., and for the other conditions, the experiment was carried out under conditions similar to those of Example 6.

Example 8

[0094] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=49 atm % and Ru/(Ru+Si)=51 atm %, the hot press conditions were set to a retention temperature of 1750° C. and a pressing pressure of 1.1 ton, and for the other conditions, the experiment was carried out under conditions similar to those of Example 6.

Example 9

[0095] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=51 atm % and Ru/(Ru+Si)=49 atm %, the hot press conditions were set to a retention temperature of 1750° C. and a pressing pressure of 1.1 ton, and for the other conditions, the experiment was carried out under conditions similar to those of Example 6.

Example 10

[0096] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=50 atm % and Ru/(Ru+Si)=50 atm %, the hot press conditions were set to a retention temperature of 1750° C. and a pressing pressure of 0.5 ton, and for the other conditions, the experiment was carried out under conditions similar to those of Example 6.

TABLE-US-00002 TABLE 2 Area- Space Thermal Composition Average weighted group of conductivity Si/ Ru/ crystal average observed Phase 1/ Electrical Seebeck Power (W/K .Math. m) (Si + Ru) (Si + Ru) grain crystal grain crystal (phase 1 + resistance coefficient factor Room at % at % size (m) size (m) phase phase 2) (Ω .Math. cm) (μV/K) (W/mK.sup.2) temperature 100° C. Example 6  50 50 2.10E−06 4.10E−06 198, 221 0.002 4.10E−03 296 2.14E−03 12.0 10.0 Example 7  50 50 3.00E−06 2.70E−05 198, 221 0.001 4.40E−03 304 2.10E−03 11.5 11.0 Example 8  49 51 2.20E−06 1.02E−05 198, 221 0.003 3.90E−03 315 2.54E−03 11.0 9.0 Example 9  51 49 3.20E−06 2.80E−05 198, 221 0.01 5.60E−03 285 1.45E−03 13.0 11.0 Example 10 50 50 1.30E−05 6.20E−05 198, 221 0005 4.10E−03 301 2.21E−03 12.0 10.0

Example 11

[0097] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=50 atm % and Ru/(Ru+Si)=50 atm %, the mixture was melted in an arc melting furnace at an input current of 30 A/g to produce an ingot, and then the ingot was pulverized with an agate mortar to obtain a powder. The powder was passed through a 300 μm-mesh sieve and then was used as a hot press raw material. The hot press conditions were set to a retention temperature of 1750° C. and a pressing pressure of 3.5 ton, and for the other conditions, the experiment was carried out under conditions similar to those of Example 6.

Example 12

[0098] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=50 atm % and Ru/(Ru+Si)=50 atm %, the mixture was melted in an arc melting furnace at an input current of 30 A/g to produce an ingot, and then the ingot was pulverized with an agate mortar to obtain a powder. The powder was passed through a 300 μm-mesh sieve and then was used as a hot press raw material. The hot press conditions were set to a retention temperature of 1200° C. and a pressing pressure of 3.5 ton, and for the other conditions, the experiment was carried out under conditions similar to those of Example 6.

Example 13

[0099] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=50 atm % and Ru/(Ru+Si)=50 atm %, the mixture was melted in an arc melting furnace at an input current of 30 A/g to produce an ingot, and subsequently the ingot was melted again in a liquid quenching apparatus and then quenched to be processed into fine wires. Those fine wires were pulverized with an agate mortar to obtain a powder. The powder was passed through a 300 μm-mesh sieve and then was used as a hot press raw material. The hot press conditions were set to a calcination temperature of 1200° C. and a pressing pressure of 3.5 ton, and for the other conditions, the experiment was carried out under conditions similar to those of Example 6.

Example 14

[0100] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=60 atm % and Ru/(Ru+Si)=40 atm %, the mixture was melted in an arc melting furnace at an input current of 30 A/g to produce an ingot, and then the ingot was pulverized with an agate mortar to obtain a powder. A metal ruthenium powder was added to the powder such that Si/(Ru+Si)=50 atm % and Ru/(Ru+Si)=50 atm % in total, and subsequently the mixture was passed through a 300 μm-mesh sieve and then was used as a hot press raw material. The hot press conditions were set to a calcination temperature of 1750° C. and a pressing pressure of 3.5 ton, and for the other conditions, the experiment was carried out under conditions similar to those of Example 6.

TABLE-US-00003 TABLE 3 Area- Space Thermal Composition Average weighted group of conductivity Si/ Ru/ crystal average observed Phase 1/ Electrical Power (W/K .Math. m) (Si + Ru) (Si + Ru) grain crystal grain crystal (phase 1 + resistance Seebeck factor Room at % at % size (m) size (m) phase phase 2) (Ω .Math. cm) (μV/K) (W/mK.sup.2) temperature 100° C. Example 11 50 50 1.00E−05 2.30E−05 198, 221 0.018 3.70E−03 381 3.92E−03 11.7 9.5 Example 12 50 50 2.90E−05 6.00E−05 198, 221 0.046 7.60E−03 377 1.87E−03 12.8 10.7 Example 13 50 50 9.00E−06 1.40E−05 198, 221 0.003 9.80E−03 338 1.17E−03 8.7 7.2 Example 14 50 50 1.90E−05 4.30E−05 198, 221 0.1 5.00E−04 135 3.65E−03 26.0 24.0

Example 15

[0101] A sample obtained by mixing a silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) such that Si/(Ru+Si)=50 atm % and Ru/(Ru+Si)=50 atm %, was brought to a molten state by high-frequency heating, and the entire amount was dropped onto a cooled oxygen-free copper roll to produce a quenched ribbon (cooling rate 8×10.sup.5 K/s). The speed of rotation of the copper roll at this time was set to about 3000 rpm. The quenched ribbon obtained here was pulverized in an agate mortar, and the resultant was passed through a 300 μm-mesh sieve and then was used as a raw material for spark plasma sintering. Sintering was performed using a carbon mold having a size of 2 cm ϕ, and in a spark plasma sintering apparatus, the raw material was heated to 1000° C. at a rate of temperature increase of 50° C./min and then was heated to 1400° C. at a rate of 20° C./min. After the material was maintained at 1400° C. for 10 minutes, the material was subjected to natural cooling. The pressure at the time of sintering was set to 2.4 ton, and the degree of vacuum was 5.0e-3 Pa. The methods for evaluating the physical properties were carried out by setting the evaluation temperature to 100° C., and for the other conditions, the methods were carried out in the same manner as in Example 1. The results are presented in Table 4.

Example 16

[0102] An experiment was carried out under conditions similar to those of Example 15 except that the pressure for spark plasma sintering was set to 1.6 ton. The results are presented in Table 4.

Example 17

[0103] An experiment was carried out under conditions similar to those of Example 15 except that the pressure for spark plasma sintering was set to 2.4 ton, and the retention temperature during sintering was set to 1300° C. The results are presented in Table 4.

Example 18

[0104] A silicon powder (purity 4 N, average particle size 300 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) and metal ruthenium (purity 99.9%, average particle size 150 μm, manufactured by Furuuchi Chemical Corp.) were mixed such that Si/(Ru+Si)=50 atm % and Ru/(Ru+Si)=50 atm %, the mixture was melted in an arc melting furnace at an input current of 30 A/g to produce an ingot, and then the ingot was pulverized with an agate mortar to obtain a powder. The powder was passed through a 300 μm-mesh sieve and then was used as a hot press raw material. The hot press conditions were set to a calcination temperature of 1750° C. and a pressing pressure of 3.5 ton, the retention time was set to 10 minutes, and for the other conditions, the experiment was carried out under conditions similar to those of Example 6. The results are presented in Table 4.

TABLE-US-00004 TABLE 4 Area- Space Thermal Composition Average weighted group of conductivity Si/ Ru/ crystal average observed Phase 1/ Electrical Power (W/K .Math. m) (Si + Ru) (Si + Ru) grain crystal grain crystal (phase 1 + resistance Seebeck factor Room at % at % size (m) size (m) phase phase 2) (Ω .Math. cm) (μV/K) (W/mK.sup.2) temperature 100° C. Example 15 50 50 2.00E−06 1.00E−05 198, 221 0.004 2.20E−03 362 5.96E−03 11.3 8.0 Example 16 50 50 1.50E−06 9.00E−06 198, 221 0.003 2.30E−03 343 5.12E−03 11.1 8.2 Example 17 50 50 1.10E+06 5.00E−06 198, 221 0.01 2.10E−03 340 5.50E−03 10.1 6.9 Example 18 50 50 7.00E+06 2.50E−05 198, 221 0.02 3.40E−03 388 4.43E−03 11.0 9.6

[0105] The results of Examples 6 to 18 thus obtained showed values higher than the thermoelectric conversion performance described in Non Patent Literatures 3 and 4 even for a temperature range of 200° C. or lower. From this, high thermoelectric conversion performance can be achieved by the present invention, even for a temperature range of 200° C. or lower.

Comparative Example 1

[0106] An alloy was obtained by a technique similar to Example 1, except that the raw materials were adjusted such that Si/(Ru+Si)=99 atm % and Ru/(Ru+Si)=1 atm %.

Comparative Example 2

[0107] An alloy was obtained by a method similar to Example 1, except that a silicon powder was used as a raw material such that Si/(Ru+Si)=100 atm %, and the calcination temperature during hot pressing was set to 1200° C.

Comparative Example 3

[0108] An alloy was obtained by a method similar to Example 1, except that a silicon powder was used as a raw material such that Si/(Ru+Si)=75 atm % and Ru/(Ru+Si)=25 atm %, and the calcination temperature during hot pressing was set to 1400° C.

Comparative Example 4

[0109] An alloy was obtained by a method similar to Example 1, except that a silicon powder was used as a raw material such that Si/(Ru+Si)=41 atm % and Ru/(Ru+Si)=59 atm %, and the calcination temperature during hot pressing was set to 1400° C.

TABLE-US-00005 TABLE 5 Area- Space Thermal Composition Average weighted group of conductivity Si/ Ru/ crystal average observed Electrical Seebeck Power (W/K .Math. m) (Si + Ru) (Si + Ru) grain crystal grain crystal resistance coefficient factor Room at % at % size (m) size (m) phase (Ω .Math. cm) (μV/K) (W/mK.sup.2) temperature 600° C. Comparative 99 1 1.10E−05 5.50E−05 227 4.90E−02 348 2.47E−04 57 21 Example 1 Comparative 100 0 1.10E−05 3.60E−05 227 6.30E−02 401 2.55E−04 123 40 Example 2 Comparative 75 25 6.00E−06 4.20E−05 225 7.80E−03 57 4.17E−05 78 61 Example 3 Comparative 41 59 8.00E−06 5.40E−05 62 5.40E−03 42 3.27E−05 89 69 Example 4

Comparative Example 5

[0110] An alloy was obtained by a technique similar to Example 6, except that the raw materials were mixed such that Si/(Ru+Si)=99 atm % and Ru/(Ru+Si)=1 atm %.

Comparative Example 6

[0111] An alloy was obtained by a method similar to Example 6, except that a silicon powder was used as a raw material such that Si/(Ru+Si)=100 atm %, and the temperature during hot pressing was set to 1200° C.

Comparative Example 7

[0112] An alloy was obtained by a method similar to Example 6, except that the raw materials were mixed such that Si/(Ru+Si)=75 atm % and Ru/(Ru+Si)=25 atm %, and the temperature during hot pressing was set to 1400° C.

Comparative Example 8

[0113] An alloy was obtained by a method similar to Example 6, except that the raw materials were mixed such that Si/(Ru+Si)=41 atm % and Ru/(Ru+Si)=59 atm %, and the calcination temperature during hot pressing was set to 1400° C.

TABLE-US-00006 TABLE 6 Area- Space Thermal Composition Average weighted group of conductivity Si/ Ru/ crystal average observed Phase 1/ Electrical Seebeck Power (W/K .Math. m) (Si + Ru) (Si + Ru) grain crystal grain crystal (phase 1 + resistance coefficient factor Room at % at % size (m) size (m) phase phase 2) (Ω .Math. cm) (μV/K) (W/mK.sup.2) temperature 600° C. Comparative 99 1 1.10E−05 5.50E−05 227 — 4.90E−02 348 2.47E−04 57 21 Example 5 Comparative 100 0 1.10E−05 3.60E−05 227 — 6.30E−02 401 2.55E−04 123 40 Example 6 Comparative 75 25 6.00E−06 4.20E−05 225 — 7.80E−03 57 4.17E−05 78 61 Example 7 Comparative 41 59 8.00E−06 5.40E−05 62 — 5.40E−03 42 3.27E−05 89 69 Example 8

[0114] In Comparative Examples 1 to 8, which are not included in the scope of the present invention, the thermoelectric conversion performance was inferior to that of the present invention, under the conditions of both 200° C. or lower and 600° C.

INDUSTRIAL APPLICABILITY

[0115] By using the present invention, a thermoelectric conversion device having high performance can be produced, and exhaust heat in a wide temperature range can be efficiently utilized.

[0116] The present invention has been described in detail with reference to specific embodiments; however, it should be apparent to those ordinarily skilled in the art that various modifications and corrections can be made without departing from the spirit and scope of the present invention.

[0117] The present application is based on a Japanese patent application filed on Jan. 18, 2019 (Japanese Patent Application No. 2019-006659), a Japanese patent application filed on Mar. 7, 2019 (Japanese Patent Application No. 2019-041217), a Japanese patent application filed on Aug. 8, 2019 (Japanese Patent Application No. 2019-146704), and a Japanese patent application filed on Dec. 17, 2019 (Japanese Patent Application No. 2019-227426), the entire disclosures thereof are incorporated herein by reference. Furthermore, all references cited herein are incorporated in their entirety.