JP4925396B2 - Thermoelectric conversion material and thermoelectric element using the same - Google Patents
Thermoelectric conversion material and thermoelectric element using the same Download PDFInfo
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Description
本発明は、高いゼーベック係数と低い電気抵抗率を有し、高い出力電圧及び出力電力を有する熱電変換材料及びそれを用いた熱電素子に関する。 The present invention relates to a thermoelectric conversion material having a high Seebeck coefficient and a low electrical resistivity, and having a high output voltage and output power, and a thermoelectric element using the thermoelectric conversion material.
清掃工場でのごみ焼却処理や、原子力発電所における発電処理などにより、あるいは、自動車や自動二輪車などのエンジンから発生する熱エネルギーの大部分は、他のエネルギーに変換されることなく大気中に廃棄されている。
エネルギーの利用効率、特に、このように廃棄されている熱エネルギーの利用効率を向上させるためには、これら大気中に廃棄・排出されている熱エネルギーを電気エネルギーに直接変換する熱電変換は有効な手段である。この変換法としては、ゼーベック効果を利用したものが知られている（例えば、特許文献１など）。このゼーベック効果を利用した熱電変換方法では、場所を取る発電設備を全く必要とせず、人体などに有害な排気ガスなどの放出もない。そして、温度差さえ存在すれば、原理的には、特別なメンテナンスなども必要なく、半永久的に使用可能である。そのため、この方法はコストの面でも有効である。
このように、熱電変換による発電は、エネルギー問題の解決の一端を担う技術として期待されているが、それを実現のためには、高い熱電変換効率を有する熱電変換材料を用いた素子（熱電素子）が必要である。
ここで、一般に、熱電変換材料の性能は、次式であらわされる性能指数又は出力因子で定義される。
性能指数＝
［ゼーベック係数（Ｖ／Ｋ）］2／（［抵抗率（Ωｍ）］・［熱伝導率（Ｗ／ｍＫ）］） （１）
出力因子＝［ゼーベック係数（Ｖ／Ｋ）］2／［抵抗率（Ωｍ）］ （２）
性能指数が高いほど熱電変換効率が高いことを示す。そして、性能指数の絶対値は、通常、金属では１０-6Ｋ-1程度、半導体では１０-5Ｋ-1程度であるが、最適化された熱電変換材料では１０-4Ｋ-1から１０-3Ｋ-1のオーダーとなる。同様に、出力因子は、１０-5Ｗ／ｍＫ2から１０-3Ｗ／ｍＫ2のオーダーで発電利用が可能となってくる。
また、室温付近から中温度域と最も汎用性の高い温度領域の熱を利用するため、耐熱性、化学的耐久性等に優れた熱電変換材料を基にした熱電変換素子が必要となる。現在、熱電変換材料としてＢｉ2Ｔｅ3やＰｂＴｅがよく用いられているが、これらの熱電変換材料では、熱電変換効率は５％前後と小さく、使用可能温度も前者で２００℃ (473K)程度、後者でも４００℃ (673K)程度であるため、より高温域の熱源には適用することができない。さらに、大気中等では酸化による特性低下が起こるため、不活性ガスにより密閉する等の処置が必要である。また、いずれの熱電変換材料においても、地球環境に負荷を与える可能性の高い毒性元素を含んでいるため、広く応用に期するには限界がある。このため、これら問題点を克服する熱電変換用材料を用いた熱電変換素子の開発が期待されている。
In order to improve the efficiency of energy use, especially the efficiency of heat energy discarded in this way, thermoelectric conversion that directly converts the heat energy discarded and discharged into the atmosphere into electrical energy is effective. Means. As this conversion method, a method using the Seebeck effect is known (for example, Patent Document 1). The thermoelectric conversion method using the Seebeck effect does not require any power generation equipment that takes up space, and does not emit exhaust gas harmful to the human body. As long as there is a temperature difference, in principle, no special maintenance or the like is required, and it can be used semipermanently. Therefore, this method is also effective in terms of cost.
Thus, power generation by thermoelectric conversion is expected as a technology that plays a part in solving energy problems, but in order to realize it, an element using a thermoelectric conversion material having high thermoelectric conversion efficiency (thermoelectric element) )is required.
Here, generally, the performance of the thermoelectric conversion material is defined by a figure of merit or an output factor expressed by the following equation.
Figure of merit =
[Seebeck coefficient (V / K)] 2 / ([resistivity (Ωm)] · [thermal conductivity (W / mK)]) (1)
Output factor = [Seebeck coefficient (V / K)] 2 / [Resistivity (Ωm)] (2)
The higher the figure of merit, the higher the thermoelectric conversion efficiency. The absolute value of the figure of merit is usually about 10 −6 K −1 for metals and about 10 −5 K −1 for semiconductors, but 10 −4 K −1 to 10 for optimized thermoelectric conversion materials. It will be on the order of -3K- 1 . Similarly, the power factor can be used in the order of 10 −5 W / mK 2 to 10 −3 W / mK 2 .
In addition, since heat in the most versatile temperature range from room temperature to medium temperature range is used, a thermoelectric conversion element based on a thermoelectric conversion material excellent in heat resistance, chemical durability, and the like is required. Currently, Bi 2 Te 3 and PbTe are often used as thermoelectric conversion materials, but these thermoelectric conversion materials have a low thermoelectric conversion efficiency of around 5%, and the usable temperature is about 200 ° C. (473 K) in the former. Even the latter is about 400 ° C. (673 K), so it cannot be applied to a heat source in a higher temperature range. Further, since the characteristics are deteriorated by oxidation in the atmosphere or the like, it is necessary to take measures such as sealing with an inert gas. In addition, since any thermoelectric conversion material contains a toxic element that is highly likely to give a load to the global environment, there is a limit to its wide application. For this reason, development of a thermoelectric conversion element using a thermoelectric conversion material that overcomes these problems is expected.
本発明の主な目的は、毒性が少ない元素により構成され、耐熱性、化学的耐久性等に優れ、室温付近から中温域温度に高い熱電変換効率を有する熱電変換材料及びそれを用いた熱電変換素子を提供することにある。 The main object of the present invention is a thermoelectric conversion material composed of an element with low toxicity, excellent in heat resistance, chemical durability, etc., having high thermoelectric conversion efficiency from near room temperature to intermediate temperature, and thermoelectric conversion using the same It is to provide an element.
請求項１に記載の本発明の熱電変換材料は、組成式:ＡｌzＧａyＩｎxＡｓuＳｂvＭrＲsＤt（式中、Ｍは遷移元素であり、Ｒは希土類元素であり、ＤはＩＶＢ族あるいはＩＩＡ、ＩＩＢ族の元素であり、０＜ｚ≦０．７、０≦ｙ≦０．７、０．２≦ｘ≦１．０、０≦ｕ≦１．０、０≦ｖ≦１．０、０≦ｒ≦０．２、０≦ｓ≦０．０５、０≦ｔ≦０．１、かつｘ＋ｙ＋ｚ＝１、ｕ＋ｖ＝１である）で表されることを特徴とする。
請求項２に記載の本発明は、請求項１に記載の熱電変換材料において、前記遷移元素Ｍは、Ｎｉ、Ｆｅ、Ｃｏ及びＭｎの中から選ばれた少なくとも一種の元素であることを特徴とする。
請求項３に記載の本発明は、請求項１又は請求項２に記載の熱電変換材料において、前記希土類元素Ｒは、Ｓｃ、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ及びＬｕの中から選ばれた少なくとも一種の元素であることを特徴とする。
請求項４に記載の本発明は、請求項１から請求項３に記載の熱電変換材料において、前記元素Ｄは、Ｇｅ、Ｓｉ、Ｍｇ、Ｚｎ及びＣの中から選ばれた少なくとも一種の元素であることを特徴とする。
請求項５に記載の本発明は、請求項１から請求項４のいずれかに記載の熱電変換材料において、せん亜鉛型結晶構造を有することを特徴とする。
請求項６に記載の本発明は、請求項１から請求項４のいずれかに記載の熱電変換材料において、ウルツ鉱型結晶構造を有することを特徴とする。
請求項７に記載の本発明は、請求項１から請求項４のいずれかに記載の熱電変換材料において、アモルファス結晶構造を有することを特徴とする。
請求項８に記載の本発明は、請求項１、２及び５から７のいずれかに記載の熱電変換材料において、前記式中、０＜ｒ≦０．２、ｓ＝０、ｔ＝０であること特徴とする。
請求項９に記載の本発明は、請求項１、３及び５から７のいずれかに記載の熱電変換材料において、前記式中、ｒ＝０、０＜ｓ≦０．０５、ｔ＝０であること特徴とする。
請求項１０に記載の本発明は、請求項１及び４〜７のいずれかに記載の熱電変換材料において、前記式中、ｒ＝０、ｓ＝０、０＜ｔ≦０．１であること特徴とする。
請求項１１に記載の本発明は、前記式中、ｚ＝０．２９、ｙ＝０．０１、ｘ＝０．７０、ｕ＝０．１、ｖ＝０．９であること特徴とする請求項１から請求項１０のいずれかに記載の熱電変換材料。
請求項１２に記載の本発明の熱電素子は、請求項１から請求項１１のいずれかに記載の熱電変換材料を用いたことを特徴とする。
The thermoelectric conversion material of the present invention according to claim 1 has a composition formula: AlzGayInxAsuSbvMrRsDt (wherein M is a transition element, R is a rare earth element, and D is an element of group IVB or IIA, IIB, 0 < z ≦ 0.7, 0 ≦ y ≦ 0.7, 0.2 ≦ x ≦ 1.0, 0 ≦ u ≦ 1.0, 0 ≦ v ≦ 1.0, 0 ≦ r ≦ 0.2, 0 ≦ s ≦ 0.05, 0 ≦ t ≦ 0.1, and x + y + z = 1 and u + v = 1).
The present invention according to claim 2 is the thermoelectric conversion material according to claim 1, wherein the transition element M is at least one element selected from Ni, Fe, Co and Mn. To do.
The invention according to claim 3 is the thermoelectric conversion material according to claim 1 or 2, wherein the rare earth element R is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd. And at least one element selected from Tb, Dy, Ho, Er, Tm, Yb and Lu.
According to a fourth aspect of the present invention, in the thermoelectric conversion material according to the first to third aspects, the element D is at least one element selected from Ge, Si, Mg, Zn and C. It is characterized by being.
A fifth aspect of the present invention is the thermoelectric conversion material according to any one of the first to fourth aspects, wherein the thermoelectric conversion material has a zinc zinc type crystal structure.
A sixth aspect of the present invention is the thermoelectric conversion material according to any one of the first to fourth aspects, wherein the thermoelectric conversion material has a wurtzite crystal structure.
A seventh aspect of the present invention is the thermoelectric conversion material according to any one of the first to fourth aspects, wherein the thermoelectric conversion material has an amorphous crystal structure.
The present invention according to claim 8 is the thermoelectric conversion material according to any one of claims 1, 2, and 5 to 7, wherein 0 <r ≦ 0.2, s = 0, t = 0. It is characterized by being.
The present invention according to claim 9 is the thermoelectric conversion material according to any one of claims 1, 3 and 5 to 7, wherein r = 0, 0 <s ≦ 0.05, and t = 0. It is characterized by being.
According to a tenth aspect of the present invention, in the thermoelectric conversion material according to any one of the first and fourth to seventh aspects, wherein r = 0, s = 0, and 0 <t ≦ 0.1. Features.
The present invention according to claim 11 is characterized in that, in the above formula, z = 0.29, y = 0.01, x = 0.70, u = 0.1, v = 0.9. The thermoelectric conversion material according to any one of claims 1 to 10.
A thermoelectric element according to a twelfth aspect of the present invention uses the thermoelectric conversion material according to any one of the first to eleventh aspects.
本発明によれば、高いゼーベック係数と低い電気抵抗率を有するとともに、耐熱性、化学的安定性等に優れた熱電変換材料を提供することができる。特に、本発明のような組成式（一般式）を有することにより、０℃ (273K)以上の温度におけるゼーベック係数の絶対値を５０μＶ／Ｋ以上、また、電気抵抗率を１０-3Ωｍ以下とすることができる。
また、本発明の熱電変換材料は、従来の金属間化合物材料では不可能であった、高温での熱電変換材料としての応用が可能である。したがって、本発明の熱電変換材料を熱電変換システム中に組み込むことにより、これまで大気中に廃棄されていた熱エネルギーを有効に利用することが可能になる。
また、本発明によれば、上述のような熱電変換材料を用いた熱電素子を提供することができる。このような熱電素子では、上述のような特徴を有する熱電変換材料を用いているので、特に、０℃ (273K)以上の温度において、出力電圧を１０ｍＶ以上、また、出力電力を１ｐＷ以上にすることができる。
ADVANTAGE OF THE INVENTION According to this invention, while having a high Seebeck coefficient and a low electrical resistivity, the thermoelectric conversion material excellent in heat resistance, chemical stability, etc. can be provided. In particular, by having the composition formula (general formula) as in the present invention, the absolute value of the Seebeck coefficient at a temperature of 0 ° C. (273 K) or higher is 50 μV / K or higher, and the electrical resistivity is 10 −3 Ωm or lower. can do.
Further, the thermoelectric conversion material of the present invention can be applied as a thermoelectric conversion material at a high temperature, which is impossible with a conventional intermetallic compound material. Therefore, by incorporating the thermoelectric conversion material of the present invention into the thermoelectric conversion system, it is possible to effectively use the heat energy that has been discarded in the atmosphere.
Moreover, according to this invention, the thermoelectric element using the above thermoelectric conversion materials can be provided. In such a thermoelectric element, since the thermoelectric conversion material having the above-described characteristics is used, the output voltage is set to 10 mV or more and the output power is set to 1 pW or more, particularly at a temperature of 0 ° C. (273 K) or more. be able to.
本発明の第１の実施の形態による熱電変換材料は、組成式：ＡｌzＧａyＩｎxＡｓuＳｂvＭrＲsＤtで表される。ここで、この組成式中、Ｍは遷移元素であり、Ｒは希土類元素であり、ＤはＩＶＢ族あるいはＩＩＡ、ＩＩＢ族の元素である。また、各指数は、０≦ｚ≦０．７、０≦ｙ≦０．７、０．２≦ｘ≦１．０、０≦ｕ≦１．０、０≦ｖ≦１．０、０≦ｒ≦０．２、０．９≦ｓ≦１．１、０≦ｔ≦０．１、かつｘ＋ｙ＋ｚ＝１、ｕ＋ｖ＝１との関係を有する。本実施の形態によれば、０℃ (273K)以上の温度でゼーベック係数の絶対値を５０μＶ／Ｋ以上、電気抵抗率を１０-3Ωｍ以下とすることができる。すなわち、高いゼーベック係数と低い電気抵抗率を有するものとすることができるので、耐熱性、化学的安定性等に優れた熱電変換材料を提供することができる。このような本発明の熱電変換材料は、従来の金属間化合物材料では不可能であった、高温での熱電変換材料としての応用が可能である。そのため、本発明の熱電変換材料を熱電変換システム中に組み込むことにより、これまで大気中に廃棄（排出）されていた熱エネルギーを有効に利用することが可能になる。
本発明の第２の実施の形態は、第１の実施の形態による熱電変換材料において、遷移元素Ｍは、Ｎｉ、Ｆｅ、Ｃｏ及びＭｎの中から選ばれた少なくとも一種の元素である。本実施の形態によれば、熱電変換材料における遷移元素Ｍを容易に選択することができる。
本発明の第３の実施の形態は、第１又は第２の実施の形態による熱電変換材料において、希土類元素Ｒは、Ｓｃ、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ及びＬｕの中から選ばれた少なくとも一種の元素である。本実施の形態によれば、熱電変換材料における希土類元素Ｒを容易に選択することができる。
本発明の第４の実施の形態は、第１から第３の実施の形態による熱電変換材料において、元素Ｄは、Ｇｅ、Ｓｉ、Ｍｇ、Ｚｎ及びＣの中から選ばれた少なくとも一種の元素である。本実施の形態によれば、熱電変換材料における元素Ｄを容易に選択することができる。
本発明の第５の実施の形態は、第１から第４の実施の形態による熱電変換材料において、この熱電変換材料は、せん亜鉛型結晶構造を有するものである。
本発明の第６の実施の形態は、第１から第４の実施の形態による熱電変換材料において、この熱電変換材料は、ウルツ鉱型結晶構造を有するものである。
本発明の第７の実施の形態は、第１から第４の実施の形態による熱電変換材料において、この熱電変換材料は、アモルファス結晶構造を有するものである。
本発明の第８の実施の形態による熱電素子は、第１から第７の実施の形態による熱電変換材料を用いたものである。本実施の形態によれば、上述のような熱電変換材料を用いた熱電素子を提供することができる。このような熱電素子では、上述のような特徴を有する熱電変換材料を用いているので、高出力特性、特に、０℃ (273K)以上の温度において、出力電圧を１０ｍＶ以上、また、出力電力を１ｐＷ以上にすることができる。
Thermoelectric conversion material according to the first embodiment of the present invention, the composition formula: represented by Al z Ga y In x As u Sb v M r R s D t. Here, in this composition formula, M is a transition element, R is a rare earth element, and D is an element of group IVB or IIA or IIB. Each index is 0 ≦ z ≦ 0.7, 0 ≦ y ≦ 0.7, 0.2 ≦ x ≦ 1.0, 0 ≦ u ≦ 1.0, 0 ≦ v ≦ 1.0, 0 ≦ r ≦ 0.2, 0.9 ≦ s ≦ 1.1, 0 ≦ t ≦ 0.1, and x + y + z = 1 and u + v = 1. According to this embodiment, the absolute value of the Seebeck coefficient can be 50 μV / K or more and the electrical resistivity can be 10 −3 Ωm or less at a temperature of 0 ° C. (273 K) or more. That is, since it can have a high Seebeck coefficient and a low electrical resistivity, a thermoelectric conversion material excellent in heat resistance, chemical stability, etc. can be provided. Such a thermoelectric conversion material of the present invention can be applied as a thermoelectric conversion material at a high temperature, which is impossible with a conventional intermetallic compound material. Therefore, by incorporating the thermoelectric conversion material of the present invention into the thermoelectric conversion system, it is possible to effectively use the thermal energy that has been discarded (discharged) into the atmosphere.
According to a second embodiment of the present invention, in the thermoelectric conversion material according to the first embodiment, the transition element M is at least one element selected from Ni, Fe, Co, and Mn. According to the present embodiment, the transition element M in the thermoelectric conversion material can be easily selected.
The third embodiment of the present invention is the thermoelectric conversion material according to the first or second embodiment, wherein the rare earth element R is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd. , Tb, Dy, Ho, Er, Tm, Yb, and Lu. According to the present embodiment, the rare earth element R in the thermoelectric conversion material can be easily selected.
According to a fourth embodiment of the present invention, in the thermoelectric conversion material according to the first to third embodiments, the element D is at least one element selected from Ge, Si, Mg, Zn, and C. is there. According to the present embodiment, the element D in the thermoelectric conversion material can be easily selected.
According to a fifth embodiment of the present invention, in the thermoelectric conversion materials according to the first to fourth embodiments, the thermoelectric conversion material has a zinc zinc type crystal structure.
The sixth embodiment of the present invention is the thermoelectric conversion material according to the first to fourth embodiments, wherein the thermoelectric conversion material has a wurtzite crystal structure.
According to a seventh embodiment of the present invention, in the thermoelectric conversion material according to the first to fourth embodiments, the thermoelectric conversion material has an amorphous crystal structure.
The thermoelectric element according to the eighth embodiment of the present invention uses the thermoelectric conversion material according to the first to seventh embodiments. According to this Embodiment, the thermoelectric element using the above thermoelectric conversion materials can be provided. In such a thermoelectric element, since the thermoelectric conversion material having the above-described characteristics is used, the output voltage is 10 mV or more and the output power is high at a high output characteristic, particularly at a temperature of 0 ° C. (273 K) or more. It can be 1 pW or more.
本発明者は、上述の熱電変換材料の現状に鑑みて種々の研究を重ねた結果、遷移元素、希土類元素、Ａｌ、Ｇａ、Ｉｎ、ＡｓおよびＳｂを構成元素として含む特定組成のＩＩＩＢ−ＶＢ族熱電変換材料が、高いゼーベック係数と低い電気抵抗率を有するとともに、電子機器を駆動させるのに耐え得る出力電圧と出力電力を出力可能なものであり、熱電変換材料として有用であることを見出し、これら材料を用いた熱電変換素子について、ここに本発明を完成するに至った。
すなわち、本発明のＩＩＩＢ−ＶＢ族熱電変換材料は、組成式：ＡｌzＧａyＩｎxＡｓuＳｂvＭrＲsＤt（式中、Ｍは遷移元素であり、Ｒは希土類元素、ＤはＩＶＢ族あるいはＩＩＡ、ＩＩＢ族の元素であり、０＜ｚ≦０．７、０≦ｙ≦０．７、０．２≦ｘ≦１．０、０≦ｕ≦１．０、０≦ｖ≦１．０、０≦ｒ≦０．２、０≦ｓ≦０．０５、０≦ｔ≦０．１、かつｘ＋ｙ＋ｚ＝１、ｕ＋ｖ＝１である）で表されることを特徴とする熱電変換材料である。また、本発明の熱電素子は、このＩＩＩＢ−ＶＢ族熱電変換材料を用いたことを特徴とする熱電素子である。本発明によれば、０℃ (273K)以上の温度で出力電圧を１０ｍＶ以上、出力電力を１ｐＷ以上とすることができるとともに、０℃(273K)以上の温度でゼーベック係数の絶対値を５０μＶ／Ｋ以上、電気抵抗率を１０−３Ωｍ以下とすることができる。ここで、上記組成式中、遷移元素（遷移金属元素）Ｍとしては、具体的には、Ｆｅ、Ｎｉ、ＣｏおよびＭｎから選ばれた少なくとも一種の元素を用いることができる。また、希土類元素Ｒとしては、具体的には、Ｓｃ、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ及びＬｕから選ばれた少なくとも一種の元素を用いることができる。そして、ｘの値は、０．２≦ｘ≦１．０であるのが好ましく、０．３≦ｘ≦０．９であるのがより好ましい。また、ｙの値は、０≦ｙ≦１．０であるのが好ましく、０．２≦ｙ≦０．８であるのがより好ましい。
The present inventor has conducted various studies in view of the present state of the above-described thermoelectric conversion material, and as a result, the group IIIB-VB having a specific composition containing transition elements, rare earth elements, Al, Ga, In, As, and Sb as constituent elements. The thermoelectric conversion material has a high Seebeck coefficient and low electrical resistivity, and can output an output voltage and output power that can withstand driving an electronic device, and is found to be useful as a thermoelectric conversion material. The present invention has been completed here for thermoelectric conversion elements using these materials.
That is, the IIIB-VB group thermoelectric conversion material of the present invention has a composition formula: AlzGayInxAsuSbvMrRsDt (wherein M is a transition element, R is a rare earth element, D is an element of group IVB or IIA, IIB, and 0 < z ≦ 0.7, 0 ≦ y ≦ 0.7, 0.2 ≦ x ≦ 1.0, 0 ≦ u ≦ 1.0, 0 ≦ v ≦ 1.0, 0 ≦ r ≦ 0.2, 0 ≦ s ≦ 0.05, 0 ≦ t ≦ 0.1, and x + y + z = 1 and u + v = 1). The thermoelectric element of the present invention is a thermoelectric element characterized by using this IIIB-VB group thermoelectric conversion material. According to the present invention, the output voltage can be 10 mV or more and the output power can be 1 pW or more at a temperature of 0 ° C. (273K) or more, and the absolute value of the Seebeck coefficient can be 50 μV / The electrical resistivity can be 10 −3 Ωm or less. Here, in the composition formula, as the transition element (transition metal element) M, specifically, at least one element selected from Fe, Ni, Co, and Mn can be used. Further, the rare earth element R is specifically selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. At least one element can be used. The value of x is preferably 0.2 ≦ x ≦ 1.0, and more preferably 0.3 ≦ x ≦ 0.9. The value of y is preferably 0 ≦ y ≦ 1.0, and more preferably 0.2 ≦ y ≦ 0.8.
このようなＩＩＩＢ−ＶＢ族熱電変換材料は、ダイヤモンド構造に似た構造であるせん亜鉛鉱構造やこのせん亜鉛鉱構造を（１１１）方向に引き伸ばした構造であるウルツ鉱構造を有している。この点を明確にするために、後述する参考例１で得たＩＩＩＢ−ＶＢ族熱電変換材料についてのＸ線回折パターンを図１示す。図１において見られる複数の回折ピークはせん亜鉛鉱型結晶構造に対応するものである。これらの結晶性は、成膜方法にもよるが、スパッタにより膜で形成した直後の試料はアモルファス構造をとっているものの、熱処理後の試料はせん亜鉛鉱構造をとることが明らかになっている。 Such a IIIB-VB group thermoelectric conversion material has a sphalerite structure that is similar to a diamond structure or a wurtzite structure that is a structure obtained by stretching this sphalerite structure in the (111) direction. In order to clarify this point, FIG. 1 shows an X-ray diffraction pattern of the IIIB-VB group thermoelectric conversion material obtained in Reference Example 1 described later. The plurality of diffraction peaks seen in FIG. 1 corresponds to the zincblende crystal structure. Although the crystallinity depends on the film formation method, it is clear that the sample immediately after being formed into a film by sputtering has an amorphous structure, but the sample after heat treatment has a sphalerite structure. .
また、図２（ａ）は後述する参考例１のＧａＩｎＳｂ試料のＥＤＸ分析パターンであり、図２（ｂ）はＩｎＡｓＳｂ試料のＥＤＸ分析パターンである。これらの組成分析により、Ｇａ、Ｉｎ、Ａｓ、ＳｂなどがＩＩＩＢ−ＶＢ族熱電変換材料の主要な構成元素であることが分かる。
上記特定の組成比を有する本発明のＩＩＩＢ−ＶＢ族熱電変換材料は、熱電素子に利用した場合、０℃ (273K)以上の温度で出力電圧が１０ｍＶ以上、出力電力が１ｐＷ以上となり、０℃(273K)以上の温度でゼーベック係数の絶対値が５０μＶ／Ｋ以上、電気抵抗率が１０-3Ωｍ以下である。本発明のＩＩＩＢ−ＶＢ族熱電変換材料は、Ｎ型もしくはＰ型の電気伝導を示し、それに応じてゼーベック係数はそれぞれ負及び正となる。このように高いゼーベック係数と低い電気抵抗率を同時に有することにより、本発明のＩＩＩＢ−ＶＢ族熱電変換材料は高い熱電変換効率を発揮することができる。さらに、このＩＩＩＢ−ＶＢ族熱電変換材料は、耐熱性、化学的耐久性等が優れており、毒性元素が少ない元素により構成されているので、熱電変換材料として実用性の高いものである。
2A shows an EDX analysis pattern of a GaInSb sample of Reference Example 1 described later, and FIG. 2B shows an EDX analysis pattern of an InAsSb sample. From these composition analyses, it can be seen that Ga, In, As, Sb and the like are the main constituent elements of the IIIB-VB group thermoelectric conversion material.
When used in a thermoelectric element, the IIIB-VB group thermoelectric conversion material of the present invention having the above specific composition ratio has an output voltage of 10 mV or more and an output power of 1 pW or more at a temperature of 0 ° C. (273 K) or more. At a temperature of (273 K) or higher, the Seebeck coefficient has an absolute value of 50 μV / K or higher and an electric resistivity of 10 −3 Ωm or lower. The IIIB-VB group thermoelectric conversion material of the present invention exhibits N-type or P-type conductivity, and the Seebeck coefficient is negative and positive accordingly. By having such a high Seebeck coefficient and a low electrical resistivity at the same time, the IIIB-VB group thermoelectric conversion material of the present invention can exhibit high thermoelectric conversion efficiency. Furthermore, this IIIB-VB group thermoelectric conversion material is excellent in heat resistance, chemical durability, and the like, and is composed of an element having a small amount of toxic elements. Therefore, it is highly practical as a thermoelectric conversion material.
また、本発明の熱電素子は、上述のＩＩＩＢ−ＶＢ族熱電変換材料を用いて構成され、所定の分量の原料物質を準備するとともに、その原料物質に所定の原料を所定の分量だけ混ぜることにより得ることができる。ここで、原料物質としては、薄膜形成を目的とするＩＩＩＢ−ＶＢ族熱電変換材料を形成し得る物質であれば特に限定されず、例えば、金属単体、窒化物等を使用することができる。ここで、Ｇａを含む原料物質である場合、Ｇａ源としては、例えば、Ｇａ金属、ＧａＮ、トリメチルガリウム（（ＣＨ3）3Ｇａ）、トリエチルＧａ、塩化Ｇａ（ＧａＣｌ2）等を使用することができる。また、希土類元素を含む原料物質である場合、希土類源としては、例えば、窒化ガドリニウム（ＧｄＮ）、トリメチルＧｄ等の窒化物を使用することができる。また、本発明のＩＩＩＢ−ＶＢ族熱電変換材料の構成元素を二種以上含む化合物を原料物質として使用してもよい。
薄膜形成手段（薄膜形成方法）は特に限定されず、スパッタ法、有機金属気相成長法、分子線エピタキシ法などを採用することができる。ここで、薄膜形成時における成膜時間及び温度については、目的とするＩＩＩＢ−ＶＢ族熱電変換材料が形成され得る条件に設定すればよく、特に限定されないが、例えば、５０℃〜８００℃ (323K〜1073K)程度の温度で、３０分〜３時間程度成膜をすればよい。なお、このような薄膜形成方法によって生成されるＩＩＩＢ−ＶＢ族熱電変換材料の元素の組成比（組成式）は、成膜時の雰囲気圧、成膜温度等の成膜条件を適宜変更することにより制御することができる。
また、薄膜であることが、本発明のＩＩＩＢ−ＶＢ族熱電変換材料の特性を発現させるための本質ではないことから、試料形態は特に薄膜に限られるものではない。例えば、ＩｎＳｂ、ＧａＳｂ、ＩｎＡｓ等や金属単体元素の原料粉末を所定量秤量し、高温において合金化して焼結する等の方法により作製されたバルク体であっても同様に熱電変換材料としての効果を発揮させることが可能である。
Moreover, the thermoelectric element of the present invention is configured using the above-mentioned IIIB-VB group thermoelectric conversion material, and prepares a predetermined amount of raw material, and mixes the predetermined raw material with the predetermined amount of the raw material. Obtainable. Here, the raw material is not particularly limited as long as it can form a IIIB-VB group thermoelectric conversion material for the purpose of forming a thin film, and for example, a single metal, a nitride, or the like can be used. Here, in the case of a source material containing Ga, for example, Ga metal, GaN, trimethyl gallium ((CH 3 ) 3 Ga), triethyl Ga, chloro chloride (GaCl 2 ) or the like may be used as the Ga source. it can. In the case of a raw material containing a rare earth element, as the rare earth source, for example, a nitride such as gadolinium nitride (GdN) or trimethyl Gd can be used. Moreover, you may use the compound containing 2 or more types of the structural element of the IIIB-VB group thermoelectric conversion material of this invention as a raw material substance.
The thin film forming means (thin film forming method) is not particularly limited, and a sputtering method, a metal organic vapor phase epitaxy method, a molecular beam epitaxy method, or the like can be employed. Here, the film formation time and temperature at the time of thin film formation may be set to the conditions under which the target IIIB-VB group thermoelectric conversion material can be formed, and are not particularly limited, for example, 50 ° C. to 800 ° C. (323K The film may be formed at a temperature of about 1073 K) for about 30 minutes to 3 hours. Note that the composition ratio (composition formula) of the elements of the IIIB-VB group thermoelectric conversion material produced by such a thin film formation method can be changed as appropriate, such as film formation conditions such as atmospheric pressure and film formation temperature. Can be controlled.
Further, since the thin film is not essential for expressing the characteristics of the IIIB-VB group thermoelectric conversion material of the present invention, the sample form is not particularly limited to the thin film. For example, even if it is a bulk body prepared by weighing a predetermined amount of raw material powders of elemental elements such as InSb, GaSb, InAs, etc., alloying and sintering at high temperature, the effect as a thermoelectric conversion material similarly Can be exhibited.
本発明のＩＩＩＢ−ＶＢ族熱電変換材料を熱電変換材料として用いた熱電変換素子（熱電素子）の一例の模式図を図３に示す。このような熱電変換素子の構造は、公知の熱電変換素子と概ね同様であり、高温部用基板１、低温部用基板２、複数のＰ型熱電変換材料３、複数のＮ型熱電変換材料４、隣接するＰ型熱電変換材料３とＮ型熱電変換材料４を電気的に接続する電極５、この熱電変換素子の入出力となる導線６等により構成される。この熱電変換素子において、本発明のＩＩＩＢ−ＶＢ族熱電変換材料をＮ型あるいはＰ型熱電変換素子として用いれば、本発明の熱電素子（熱電変換素子）を構成することができる。
以下、具体的な複数の実施例を示し、本発明の特徴とするところをより一層明確にする。
（参考例１）
The schematic diagram of an example of the thermoelectric conversion element (thermoelectric element) which used the IIIB-VB group thermoelectric conversion material of this invention as a thermoelectric conversion material is shown in FIG. The structure of such a thermoelectric conversion element is substantially the same as that of a known thermoelectric conversion element, and is a high temperature part substrate 1, a low temperature part substrate 2, a plurality of P type thermoelectric conversion materials 3, and a plurality of N type thermoelectric conversion materials 4. The electrode 5 electrically connects the adjacent P-type thermoelectric conversion material 3 and N-type thermoelectric conversion material 4, the conductive wire 6 serving as the input / output of this thermoelectric conversion element, and the like. In this thermoelectric conversion element, if the IIIB-VB group thermoelectric conversion material of the present invention is used as an N-type or P-type thermoelectric conversion element, the thermoelectric element (thermoelectric conversion element) of the present invention can be configured.
Hereinafter, a plurality of specific examples will be shown to further clarify the features of the present invention.
( Reference Example 1)
Ｉｎ源として有機金属トリメチルインジウム（ＴＭＩｎ）、Ｓｂ源として有機金属トリメチルアンチモン（Ｓｂ）を用いて、有機金属気相成長法によりＩｎＳｂ薄膜を作製した。なお、成膜時間は３時間、成膜温度は５５０℃ (823K)とした。基板にはサファイアを使用した。得られたＩＩＩＢ−ＶＢ族熱電変換材料は、組成式ＩｎＳｂで表されるものであった。
ここで、得られたＩＩＩＢ−ＶＢ族熱電変換材料の１００℃〜４５０℃ (373K〜723K)におけるゼーベック係数の温度依存性を図４のグラフに示す。図４のグラフから分かるように、このＩＩＩＢ−ＶＢ族熱電変換材料は、１００℃〜４５０℃ (373K〜723K)の温度範囲において、ゼーベック係数の絶対値が５０μＶ／Ｋ以上となっている。また、このＩＩＩＢ−ＶＢ族熱電変換材料について、直流四端子法により測定した電気抵抗率の温度依存性を図５のグラフに示す。図５のグラフから分かるように、このＩＩＩＢ−ＶＢ族熱電変換材料の電気抵抗率は、温度の上昇に伴って減少する半導体的（半導体類似の）挙動を示し、例えば、４５０℃ (723K)における電気抵抗率は１０-5Ωｍ程度という低い値となっている。
An InSb thin film was prepared by metal organic vapor phase epitaxy using organometallic trimethylindium (TMIn) as the In source and organometallic trimethylantimony (Sb) as the Sb source. The film formation time was 3 hours, and the film formation temperature was 550 ° C. (823 K). Sapphire was used for the substrate. The obtained IIIB-VB group thermoelectric conversion material was represented by the composition formula InSb.
Here, the temperature dependence of the Seebeck coefficient at 100 ° C. to 450 ° C. (373 K to 723 K) of the obtained IIIB-VB thermoelectric conversion material is shown in the graph of FIG. As can be seen from the graph of FIG. 4, the IIIB-VB group thermoelectric conversion material has an Seebeck coefficient absolute value of 50 μV / K or more in a temperature range of 100 ° C. to 450 ° C. (373 K to 723 K). Moreover, about this IIIB-VB group thermoelectric conversion material, the temperature dependence of the electrical resistivity measured by the direct-current four-terminal method is shown in the graph of FIG. As can be seen from the graph of FIG. 5, the electrical resistivity of the IIIB-VB thermoelectric conversion material shows a semiconducting (semiconductor-like) behavior that decreases with increasing temperature, for example, at 450 ° C. (723 K). The electrical resistivity is as low as about 10 −5 Ωm.
次に、このＩＩＩＢ−ＶＢ族熱電変換材料を用いて、熱電素子を作製した。得られた熱電素子の概略的構造を図６に示す。この熱電素子の出力特性（出力電圧及び出力電力）のグラフを図７（ａ）及び図７（ｂ）にそれぞれ示す。図７（ａ）及び図７（ｂ）のグラフから分かるように、ＩＩＩＢ−ＶＢ族熱電変換材料を用いた熱電素子は、室温から１００℃ (373K)の温度差で出力電圧１ｍＶ、出力電力１ｎＷ程度と高い熱電変換効率を示した。
（参考例２）
Next, the thermoelectric element was produced using this IIIB-VB group thermoelectric conversion material. FIG. 6 shows a schematic structure of the obtained thermoelectric element. Graphs of the output characteristics (output voltage and output power) of the thermoelectric element are shown in FIGS. 7 (a) and 7 (b), respectively. As can be seen from the graphs of FIGS. 7A and 7B, the thermoelectric element using the IIIB-VB group thermoelectric conversion material has an output voltage of 1 mV and an output power of 1 nW at a temperature difference from room temperature to 100 ° C. (373 K). A high thermoelectric conversion efficiency was shown.
( Reference Example 2)
構成元素の数を増やしても本発明の効果が発現することを参考例２として示す。参考例１の組成にＧａを更に加え、参考例１と同様な方法で、組成式：Ｇａ0.97Ｉｎ0.03Ｓｂで表されるＩＩＩＢ−ＶＢ族熱電変換材料を作製した。
ここで、得られたＩＩＩＢ−ＶＢ族熱電変換材料の１００℃〜４５０℃ (373K〜723K)におけるゼーベック係数の温度依存性を図８のグラフに示す。図８のグラフから分かるように、このＩＩＩＢ−ＶＢ族熱電変換材料は、１００℃〜４５０℃(373K〜723K)の温度範囲において、ゼーベック係数の絶対値が５０μＶ／Ｋ以上となっている。また、このＩＩＩＢ−ＶＢ族熱電変換材料について、直流四端子法により測定した電気抵抗率の温度依存性を図９のグラフに示す。図９のグラフから分かるように、このＩＩＩＢ−ＶＢ族熱電変換材料の電気抵抗率は、温度の上昇に伴って減少する半導体的（半導体類似の）挙動を示し、参考例１と同様に、例えば、４５０℃(723K)における電気抵抗率は１０-5Ωｍ程度という低い値となっている。
さらに、図１０には、Ｇａ0.97Ｉｎ0.03ＳｂとＩｎＡｓの４対で構成されば熱電素子の負荷特性を示す。いずれの特性においても、出力開放電圧が１mV以上を示し、最大出力電力は１nWを上回った値を得た。
ここで、原料の構成元素の数を増やすことは、その電気的特性のみならず、熱伝導率にも影響を与えることが予想される。すなわち、ＳｉやＧｅ等の単元素半導体に比べ、ＳｉとＧｅの混晶組成、例えばＳｉ0.5Ｇｅ0.5では熱伝導率が１／２０程度になることから類推して、本発明のＩＩＩＢ−ＶＢ族熱電変換材料においても、混晶組成を複雑化していくことは熱伝導率の低減を導き、性能向上をもたらすと考えられる。そのため、参考例２のように混晶を複雑化することにより電気的性能が大幅に変化しない場合、性能指数はさらに向上しているものと考えられる。
Reference Example 2 shows that the effect of the present invention is exhibited even when the number of constituent elements is increased. Further adding Ga to the composition of Example 1, in the same manner as in Reference example 1, the composition formula: were prepared IIIB-VB Group thermoelectric conversion material represented by Ga 0.97 In 0.03 Sb.
Here, the temperature dependence of the Seebeck coefficient at 100 ° C. to 450 ° C. (373 K to 723 K) of the obtained IIIB-VB thermoelectric conversion material is shown in the graph of FIG. As can be seen from the graph of FIG. 8, this IIIB-VB group thermoelectric conversion material has an absolute value of Seebeck coefficient of 50 μV / K or more in a temperature range of 100 ° C. to 450 ° C. (373 K to 723 K). Moreover, about this IIIB-VB group thermoelectric conversion material, the temperature dependence of the electrical resistivity measured by the direct-current four-terminal method is shown in the graph of FIG. As can be seen from the graph of FIG. 9, the electrical resistivity of the IIIB-VB Group thermoelectric conversion materials exhibit semiconducting (semiconductor similar) behavior which decreases with increasing temperature, in the same manner as in Reference Example 1, for example, The electrical resistivity at 450 ° C. (723 K) is as low as about 10 −5 Ωm.
Further, FIG. 10 shows the load characteristics of a thermoelectric element if it is composed of four pairs of Ga 0.97 In 0.03 Sb and InAs. In all the characteristics, the output open circuit voltage was 1 mV or more, and the maximum output power was higher than 1 nW.
Here, increasing the number of constituent elements of the raw material is expected to affect not only the electrical characteristics but also the thermal conductivity. That is, the IIIB-VB group of the present invention is analogized by the fact that the thermal conductivity is about 1/20 in the mixed crystal composition of Si and Ge, for example, Si 0.5 Ge 0.5 , as compared with single element semiconductors such as Si and Ge. Even in the thermoelectric conversion material, it is considered that making the mixed crystal composition complicated leads to a decrease in thermal conductivity and an improvement in performance. Therefore, when the electrical performance does not change significantly by complicating the mixed crystal as in Reference Example 2, it is considered that the figure of merit is further improved.
原料として用いる遷移元素化合物として以下の表１に示す化合物を特に追加すること以外は、参考例１と概ね同様にして、組成式：Ａｌ0.29Ｇａ0.01Ｉｎ0.70Ｍ0.20Ａｓ0.1Ｓｂ0.9で表されるＩＩＩＢ−ＶＢ族熱電変換材料を作製した。組成式中、Ｍは遷移金属であり、具体的には、実施例３〜６に対し、Ｎｉ、Ｆｅ、Ｃｏ及びＭｎの一種類を順に含むものである。各実施形態において得られたＩＩＩＢ−ＶＢ族熱電変換材料について、所定の測定温度におけるゼーベック係数、電気抵抗率、出力電圧及び出力電力の測定結果を表１に示す。 It is represented by the composition formula: Al 0.29 Ga 0.01 In 0.70 M 0.20 As 0.1 Sb 0.9 in substantially the same manner as in Reference Example 1 except that the compounds shown in Table 1 below are particularly added as the transition element compounds used as raw materials. A IIIB-VB group thermoelectric conversion material was produced. In the composition formula, M is a transition metal, and specifically includes one kind of Ni, Fe, Co, and Mn in order with respect to Examples 3 to 6. Table 1 shows the measurement results of Seebeck coefficient, electrical resistivity, output voltage, and output power at a predetermined measurement temperature for the IIIB-VB group thermoelectric conversion material obtained in each embodiment.
この表１から分かるように、いずれの遷移元素化合物を含むＩＩＩＢ−ＶＢ族熱電変換材料においても、高いゼーベック係数と低い電気抵抗率を有するとともに、高い出力電圧及び出力電力を有することが分かる。
（実施例７〜２２）
As can be seen from Table 1, the IIIB-VB group thermoelectric conversion material containing any transition element compound has a high Seebeck coefficient and a low electrical resistivity, as well as a high output voltage and output power.
(Examples 7 to 22)
原料として用いる希土類元素として以下の表２に示す元素を特に追加すること以外は、参考例１と概ね同様にして、組成式：Ａｌ0.29Ｇａ0.01Ｉｎ0.70Ｒ0.05Ａｓ0.1Ｓｂ0.9で表されるＩＩＩＢ−ＶＢ族熱電変換材料を作製した。組成式中、Ｒは希土類元素であり、具体的には、実施例７〜２２に対し、Ｇｄ、Ｓｃ、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ及びＬｕの一種の元素を順に含むものである。各実施形態において得られたＩＩＩＢ−ＶＢ族熱電変換材料について、所定の測定温度におけるゼーベック係数、電気抵抗率、出力電圧及び出力電力の測定結果を表２に示す。 IIIB represented by the composition formula: Al 0.29 Ga 0.01 In 0.70 R 0.05 As 0.1 Sb 0.9 in substantially the same manner as in Reference Example 1 except that the elements shown in Table 2 below are particularly added as rare earth elements used as raw materials. A -VB group thermoelectric conversion material was prepared. In the composition formula, R is a rare earth element. Specifically, for Examples 7 to 22, Gd, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, It contains one kind of element of Tm, Yb and Lu in order. Table 2 shows the measurement results of the Seebeck coefficient, the electrical resistivity, the output voltage, and the output power at a predetermined measurement temperature for the IIIB-VB group thermoelectric conversion material obtained in each embodiment.
この表２から分かるように、いずれの希土類元素を含むＩＩＩＢ−ＶＢ族熱電変換材料においても、高いゼーベック係数と低い電気抵抗率を有するとともに、高い出力電圧及び出力電力を有することが分かる。
また、これらの希土類元素を添加したすべての実施例において、ＩＩＩＢ−ＶＢ族熱電変換材料の伝導型はＮ型となった。Ｇｄ、Ｓｃ、Ｓｍ、Ｔｂにおいては低い電気抵抗率と高いゼーベック係数を同時に満たしており、熱電変換材料として特に有用である。さらに、これらの希土類元素を添加した組成式では参考例２と同様の理由から、混晶化の効果により熱伝導率の低減を期待することができ、それにより、性能指数の向上を期待することができる。
（実施例２３〜２７）
As can be seen from Table 2, the IIIB-VB group thermoelectric conversion material containing any rare earth element has a high Seebeck coefficient and a low electrical resistivity, as well as a high output voltage and output power.
Moreover, in all Examples to which these rare earth elements were added, the conduction type of the IIIB-VB group thermoelectric conversion material was N-type. Gd, Sc, Sm, and Tb satisfy low electrical resistivity and high Seebeck coefficient at the same time, and are particularly useful as thermoelectric conversion materials. Furthermore, in the composition formula with these rare earth elements added, for the same reason as in Reference Example 2, it is possible to expect a decrease in thermal conductivity due to the effect of mixed crystallization, thereby expecting an improvement in the figure of merit. Can do.
(Examples 23 to 27)
原料として用いるＩＶＢ族あるいはＩＩＡ、ＩＩＢ族の元素として以下の表３に示す元素を特に追加すること以外は、参考例１と概ね同様にして、組成式：Ａｌ0.29Ｇａ0.01Ｉｎ0.70Ｄ0.01Ａｓ0.1Ｓｂ0.9で表される熱電変換材料を作製した。組成式中、ＤはＩＶＢ族の元素（Ｇｅ、Ｓｉ、Ｃ）あるいはＩＩＡ、ＩＩＢ族の元素（Ｚｎ、Ｍｇ）であり、実施例２３〜２７に対し、いずれか一種の元素を含むものである。各実施形態において得られたＩＩＩＢ−ＶＢ族熱電変換材料について、所定の測定温度におけるゼーベック係数、電気抵抗率、出力電圧及び出力電力の測定結果を表３に示す。 The composition formula: Al 0.29 Ga 0.01 In 0.70 D 0.01 As 0.1 is substantially the same as in Reference Example 1 except that the elements shown in Table 3 below are particularly added as elements of Group IVB or IIA and IIB used as raw materials. A thermoelectric conversion material represented by Sb 0.9 was produced. In the composition formula, D is a group IVB element (Ge, Si, C) or a group IIA or IIB element (Zn, Mg), and includes any one of the elements in Examples 23 to 27. Table 3 shows the measurement results of Seebeck coefficient, electrical resistivity, output voltage, and output power at a predetermined measurement temperature for the IIIB-VB group thermoelectric conversion material obtained in each embodiment.
この表３から分かるように、いずれのＩＶＢ族あるいはＩＩＡ、ＩＩＢ族の元素を含むＩＩＩＢ−ＶＢ族熱電変換材料においても、高いゼーベック係数と低い電気抵抗率を有するとともに、高い出力電圧及び出力電力を有することが分かる。
（実施例２８〜３０）
As can be seen from Table 3, any IIIB-VB group thermoelectric conversion material containing any IVB group or IIA or IIB group element has a high Seebeck coefficient and a low electrical resistivity, and a high output voltage and output power. It turns out that it has.
(Examples 28 to 30)
一般式ＡｌｚＧａ0.01ＩｎｘＡｓ0.1Ｓｂ0.9で表されるＩＩＩＢ−ＶＢ族熱電変換材料を作製した。ここで、各実施形態におけるｘ、ｚは、以下の表４に示されるような値である。各実施形態において得られたＩＩＩＢ−ＶＢ族熱電変換材料について、所定の測定温度におけるゼーベック係数、電気抵抗率、出力電圧及び出力電力の測定結果を表４に示す。 A IIIB-VB group thermoelectric conversion material represented by the general formula AlzGa 0.01 InxAs 0.1 Sb 0.9 was produced. Here, x and z in each embodiment are values as shown in Table 4 below. For the IIIB-VB group thermoelectric conversion material obtained in each embodiment, Table 4 shows the measurement results of Seebeck coefficient, electrical resistivity, output voltage and output power at a predetermined measurement temperature.
実施例２８、２９及び３０を比較すると、Ｉｎの組成比率が大きくなるに従い、ゼーベック係数、電気抵抗率が減少する傾向を示している。これは、Ｉｎの増加が電子濃度を増加させていることを意味すると考えられる。
なお、本発明のＩＩＩＢ−ＶＢ族熱電変換材料を基に作製された熱電素子は、ＡｓやＳｂなどの有害な元素を含んでいる。しかしながら、これらの元素は、それを単体でかつ大量に摂取した場合にのみ人体に有害であり、実際には、両元素とも生体にとって必須元素であることは明らかとなっている。
When Examples 28, 29 and 30 are compared, the Seebeck coefficient and the electrical resistivity tend to decrease as the In composition ratio increases. This is thought to mean that an increase in In increases the electron concentration.
In addition, the thermoelectric element produced based on the IIIB-VB group thermoelectric conversion material of this invention contains harmful elements, such as As and Sb. However, these elements are harmful to the human body only when they are ingested alone and in large quantities. In fact, it is clear that both elements are essential elements for the living body.
１ 高温部用基板
２ 低温部用基板
３ Ｐ型熱電変換材料
４ Ｎ型熱電変換材料
５ 電極
６ 導線
DESCRIPTION OF SYMBOLS 1 Substrate for high temperature part 2 Substrate for low temperature part 3 P-type thermoelectric conversion material 4 N-type thermoelectric conversion material 5 Electrode 6 Conductor
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