JP2008159680A - Yb-ae-fe-co-sb (ae:ca, sr, ba, cu, ag, au)-based thermoelectric conversion material - Google Patents
Yb-ae-fe-co-sb (ae:ca, sr, ba, cu, ag, au)-based thermoelectric conversion material Download PDFInfo
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Abstract
Description
本発明は、熱エネルギーを電気に、あるいは電気を熱エネルギーに直接変換できる熱電変換素子に使用する熱電変換材料に関し、特にｐ−型およびｎ−型Ｙｂ−ＡＥ−Ｆｅ−Ｃｏ−Ｓｂ（ＡＥ：Ｃａ、Ｓｒ、Ｂａ、Ｃｕ、Ａｇ、Ａｕ）系熱電変換材料に関する。 The present invention relates to a thermoelectric conversion material used for a thermoelectric conversion element capable of directly converting heat energy into electricity or electricity into heat energy, and in particular, p-type and n-type Yb-AE-Fe-Co-Sb (AE: (Ca, Sr, Ba, Cu, Ag, Au) related to thermoelectric conversion materials.
近年、環境負荷の低減が世界的規模で推進される傾向にあり、エネルギーの効率的利用促進の一環として、熱機関などから発生する廃熱を回収し、電気へ変換する技術が盛んに研究開発されている。熱電変換材料は熱を電気に直接変換する、あるいは電気を印加して加熱・冷却できる材料であり、ｐ−型熱電変換材料とｎ−型熱電変換材料とを組み合わせ、一つの熱電変換素子が形成される。熱電変換素子を使用すれば、従来あまり利用されていなかった排熱を電気に変換してエネルギーを有効に活用することができる。 In recent years, there has been a tendency to reduce the environmental burden on a global scale, and as a part of promoting the efficient use of energy, technologies to recover waste heat generated from heat engines and convert it to electricity are actively researched and developed. Has been. A thermoelectric conversion material is a material that directly converts heat into electricity, or that can be heated and cooled by applying electricity. A p-type thermoelectric conversion material and an n-type thermoelectric conversion material are combined to form a single thermoelectric conversion element. Is done. If a thermoelectric conversion element is used, it is possible to effectively use energy by converting waste heat, which has not been used so far, into electricity.
熱電変換材料の性質は、性能指数Ｚによって評価される。性能指数Ｚとは、ゼーベック係数Ｓ、熱伝導率κおよび電気抵抗率ρを用いた以下の式（１）によって表される。
Ｚ＝Ｓ２／（κρ） ・・・式（１）
また、熱電変換材料の性質は、性能指数Ｚと温度Ｔとの積によって評価されることがある。この場合には、式（１）の両辺に温度Ｔ（ここで、Ｔは絶対温度）を乗じて以下の式（２）とする。
ＺＴ＝Ｓ２Ｔ／（κρ） ・・・式（２）
式（２）に示したＺＴは無次元性能指数と呼ばれ、熱電変換材料の性能を示す指標になる。熱電変換材料は、このＺＴの値が大きいほど、その温度Ｔにおける熱電性能が高いことになる。式（１）、式（２）から、優れた熱電変換材料とは、無次元性能指数ＺＴの値を大きくできる材料、すなわちゼーベック係数Ｓが大きく、熱伝導率κおよび電気抵抗率ρが小さい材料である。
The property of the thermoelectric conversion material is evaluated by the figure of merit Z. The figure of merit Z is represented by the following formula (1) using the Seebeck coefficient S, the thermal conductivity κ, and the electrical resistivity ρ.
Z = S 2 / (κρ) (1)
Moreover, the property of the thermoelectric conversion material may be evaluated by the product of the figure of merit Z and the temperature T. In this case, the following equation (2) is obtained by multiplying both sides of the equation (1) by a temperature T (where T is an absolute temperature).
ZT = S 2 T / (κρ) (2)
ZT shown in Formula (2) is called a dimensionless figure of merit and serves as an index indicating the performance of the thermoelectric conversion material. The thermoelectric conversion material has higher thermoelectric performance at the temperature T as the ZT value is larger. From Equations (1) and (2), an excellent thermoelectric conversion material is a material that can increase the value of the dimensionless figure of merit ZT, that is, a material that has a large Seebeck coefficient S, and a small thermal conductivity κ and electrical resistivity ρ. It is.
熱電変換材料の最大変換効率ηｍａｘは、以下の式（３）で表される。
ηｍａｘ＝{（Ｔｈ−Ｔｃ）／Ｔｈ}{（Ｍ−１）／（Ｍ＋（Ｔｃ／Ｔｈ））} ・・・式（３）
式（３）のＭは、以下の式（４）によって表される。ここでＴｈは熱電変換材料の高温端の温度、Ｔｃは低温端の温度である。
Ｍ＝{１＋Ｚ（Ｔｈ＋Ｔｃ）／２}−０．５ ・・・式（４）
上記の式（１）〜（４）から、熱電変換材料の熱電変換効率は、性能指数および高温端と低温端との温度差が大きいほど、向上することが分かる。
The maximum conversion efficiency η max of the thermoelectric conversion material is represented by the following formula (3).
η max = {(T h −T c ) / T h } {(M−1) / (M + (T c / T h ))} Equation (3)
M in the formula (3) is represented by the following formula (4). Here, Th is the temperature at the high temperature end of the thermoelectric conversion material, and T c is the temperature at the low temperature end.
M = {1 + Z ( Th + Tc ) / 2} -0.5 ... Formula (4)
From the above formulas (1) to (4), it can be seen that the thermoelectric conversion efficiency of the thermoelectric conversion material improves as the performance index and the temperature difference between the high temperature end and the low temperature end increase.
現在までに研究されてきた熱電変換材料には、Ｂｉ２Ｔｅ３系、ＰｂＴｅ系、ＧｅＴｅ−ＡｇＳｂＴｅ２系、ＳｉＧｅ系、Ｆｅ２Ｓｉ系、Ｚｎ４Ｓｂ３系、Ｂ４Ｃ系、スクッテルダイト構造を有するＬａｘＦｅ３ＣｏＳｂ１２（０＜ｘ≦１）およびＹｂｙＣｏ４Ｓｂ１２（０＜ｙ≦１）系材料、ＮａＣｏ２Ｏ４、Ｃａ３Ｃｏ４Ｏ９、Ｂｉ２Ｓｒ２Ｃｏ２Ｏ８系酸化物などがある。 Thermoelectric conversion materials that have been studied so far include Bi 2 Te 3 system, PbTe system, GeTe-AgSbTe 2 system, SiGe system, Fe 2 Si system, Zn 4 Sb 3 system, B 4 C system, skutterudite. La x Fe 3 CoSb 12 (0 <x ≦ 1) and Yb y Co 4 Sb 12 (0 <y ≦ 1) materials having a structure, NaCo 2 O 4 , Ca 3 Co 4 O 9 , Bi 2 Sr 2 Co 2 O 8 -based oxides and the like.
上記の熱電変換材料の中で実用化されているのはＢｉ２Ｔｅ３系のみである。Ｂｉ２Ｔｅ３系熱電変換素子は、主として、低温域での用途開発がなされているが、熱電変換効率が１０％未満と低いので、スペースユーティリティーが小さいペルチェ素子などに用途が限られている。 Among the thermoelectric conversion materials, only the Bi 2 Te 3 system is put into practical use. Bi 2 Te 3 -based thermoelectric conversion elements are mainly developed for use in a low temperature range, but their thermoelectric conversion efficiency is as low as less than 10%, so their use is limited to Peltier elements with a small space utility.
また、１９９６年に報告されたＺｎ４Ｓｂ３熱電変換材料は、ｐ−型で無次元性能指数ＺＴ＝１という高い熱電性能を有する。しかしながら、４００℃以上の温度に達した場合、固相変態して熱電性能が低下するという欠点があり、用途が４００℃以下の範囲に限られる。 Moreover, the Zn 4 Sb 3 thermoelectric conversion material reported in 1996 has a high thermoelectric performance of p-type and dimensionless figure of merit ZT = 1. However, when the temperature reaches 400 ° C. or higher, there is a drawback that the thermoelectric performance is deteriorated due to solid phase transformation, and the application is limited to a range of 400 ° C. or lower.
１０年前から、「Ｐｈｏｎｏｎ Ｇｌａｓｓ ａｎｄ Ｅｌｅｃｔｒｏｎ Ｃｒｙｓｔａｌ」というコンセプトに基づき、ラットリング効果を利用したスクッテルダイト熱電変換材料の開発がなされてきた。その結果、３００〜６００℃の中温域で使用可能なＬａ（Ｃｅ）−Ｆｅ−Ｓｂ系およびＹｂ−Ｃｏ−Ｓｂ系熱電変換材料、特にｐ−型ＬａｘＦｅ３ＣｏＳｂ１２（０＜ｘ≦１）およびｎ−型ＹｂｙＣｏ４Ｓｂ１２（０＜ｙ≦１）熱電変換材料が開発され、その熱電性能の無次元性能指数ＺＴはそれぞれ０．７〜０．８と比較的高い値を示している（特許文献１および２）。なお、特許文献１によれば、ｐ−型ＣｅＦｅ４Ｓｂ１２熱電材料の無次元性能指数（ＺＴ）は４５０℃で１．４に達しているが、本発明者による追試では約０．５〜０．６であった。
しかしながら、高い熱電変換効率を示す熱電変換素子を作るためには、ｐ−型、ｎ−型共に無次元性能指数ＺＴ＞１を有し、かつ熱的に安定であることが要求されるが、従来の材料はこの要求を満たすことは困難であった。 However, in order to make a thermoelectric conversion element exhibiting high thermoelectric conversion efficiency, both p-type and n-type are required to have a dimensionless figure of merit ZT> 1 and to be thermally stable. Conventional materials have been difficult to meet this requirement.
本発明は、上記の点に鑑み、３００〜６００℃の温度範囲で従来の熱電変換材料よりも熱電性能が高い熱電変換材料を提供するものである。 This invention provides the thermoelectric conversion material whose thermoelectric performance is higher than the conventional thermoelectric conversion material in the temperature range of 300-600 degreeC in view of said point.
上記課題を解決するために、本発明によれば、Ｙｂ−ＡＥ−Ｆｅ−Ｃｏ−Ｓｂ系熱電変換材料であって、一般式ＹｂｘＡＥｙＦｅｚＣｏｕＳｂｖ（０＜ｘ≦１、０＜ｙ≦１、０＜ｘ＋ｙ≦１、０≦ｚ≦４、０≦ｕ≦４、３≦ｚ＋ｕ≦５、１０≦ｖ≦１５）で表される構造を有し、ＡＥはＣａ、Ｓｒ、Ｂａ、Ｃｕ、Ａｇ、およびＡｕからなる群から選択される少なくとも一種であることを特徴とするＹｂ−ＡＥ−Ｆｅ−Ｃｏ−Ｓｂ系熱電変換材料が提供される。 In order to solve the above problems, according to the present invention, there is provided a Yb-AE-Fe-Co- Sb based thermoelectric conversion material, the general formula Yb x AE y Fe z Co u Sb v (0 <x ≦ 1, 0 <y ≦ 1, 0 <x + y ≦ 1, 0 ≦ z ≦ 4, 0 ≦ u ≦ 4, 3 ≦ z + u ≦ 5, 10 ≦ v ≦ 15), and AE is Ca, Sr There is provided a Yb—AE—Fe—Co—Sb thermoelectric conversion material which is at least one selected from the group consisting of Ba, Cu, Ag, and Au.
本発明において、結晶格子内にＦｅとＣｏとを、およびＹｂとＡＥとを同時に混在させることでフォノン散乱を強く起こすことができる。このフォノン散乱が熱伝導率κを低下させるので、式（２）より無次元性能指数ＺＴの値を大きくすることが可能である。 In the present invention, phonon scattering can be strongly caused by simultaneously mixing Fe and Co and Yb and AE in the crystal lattice. Since this phonon scattering lowers the thermal conductivity κ, it is possible to increase the value of the dimensionless figure of merit ZT from the equation (2).
さらに、本発明では、ＹｂｘＡＥｙＦｅｚＣｏｕＳｂｖ中のｚおよびｕ、すなわちＦｅおよびＣｏの量を調整することによって、出力因子Ｐ（＝Ｓ２／ρ）の値を大きくすることも可能である。この効果により無次元性能指数ＺＴの値をより一層大きくすることができる。 Furthermore, in the present invention, the value of the output factor P (= S 2 / ρ) is increased by adjusting the amount of z and u in Yb x AE y Fe z Co u Sb v , that is, the amount of Fe and Co. Is also possible. By this effect, the value of the dimensionless figure of merit ZT can be further increased.
また、本発明によれば、上記一般式ＹｂｘＡＥｙＦｅｚＣｏｕＳｂｖにおける元素Ｆｅまたは元素Ｃｏの少なくとも一部が、元素Ｒｕ、Ｏｓ、Ｒｈ、Ｉｒ、Ｎｉ、Ｐｄ、およびＰｔからなる群から選択される少なくとも一種によって置換されたＹｂ−ＡＥ−Ｆｅ−Ｃｏ−Ｓｂ系熱電変換材料が提供される。 Further, according to the present invention, at least part of the element Fe or the element Co in the general formula Yb x AE y Fe z Co u Sb v is composed of the elements Ru, Os, Rh, Ir, Ni, Pd, and Pt. A Yb—AE—Fe—Co—Sb-based thermoelectric conversion material substituted with at least one selected from the group is provided.
元素Ｆｅまたは元素Ｃｏの少なくとも一部を元素Ｒｕ、Ｏｓ、Ｒｈ、Ｉｒ、Ｎｉ、Ｐｄ、およびＰｔからなる群から選択される少なくとも一種の元素で置換することにより、熱伝導率κをさらに低下させることができ、熱電変換材料の熱電性能を表す無次元性能指数ＺＴの値をさらに大きくすることができる。 Substituting at least part of the element Fe or element Co with at least one element selected from the group consisting of the elements Ru, Os, Rh, Ir, Ni, Pd, and Pt further reduces the thermal conductivity κ. The dimensionless figure of merit ZT representing the thermoelectric performance of the thermoelectric conversion material can be further increased.
本発明のｐ−型およびｎ−型のＹｂ−ＡＥ−Ｆｅ−Ｃｏ−Ｓｂ（ＡＥ：Ｃａ、Ｓｒ、Ｂａ、Ｃｕ、Ａｇ、Ａｕ）系熱電変換材料を用いることにより、３００〜６００℃の中温領域で高い熱電性能を有し、変換効率の高い熱電変換素子を提供することが可能である。 By using the p-type and n-type Yb—AE—Fe—Co—Sb (AE: Ca, Sr, Ba, Cu, Ag, Au) -based thermoelectric conversion material of the present invention, a medium temperature of 300 to 600 ° C. It is possible to provide a thermoelectric conversion element having high thermoelectric performance in a region and high conversion efficiency.
本発明の熱電変換材料は、Ｙｂ−ＡＥ−Ｆｅ−Ｃｏ−Ｓｂ系熱電変換材料であって、一般式ＹｂｘＡＥｙＦｅｚＣｏｕＳｂｖ（０＜ｘ≦１、０＜ｙ≦１、０＜ｘ＋ｙ≦１、０≦ｚ≦４、０≦ｕ≦４、３≦ｚ＋ｕ≦５、１０≦ｖ≦１５）で表される構造を有し、ＡＥはＣａ、Ｓｒ、Ｂａ、Ｃｕ、Ａｇ、およびＡｕからなる群から選択される少なくとも一種であることを特徴とする。 The thermoelectric conversion material of the present invention is an Yb-AE-Fe-Co- Sb based thermoelectric conversion material, the general formula Yb x AE y Fe z Co u Sb v (0 <x ≦ 1,0 <y ≦ 1, 0 <x + y ≦ 1, 0 ≦ z ≦ 4, 0 ≦ u ≦ 4, 3 ≦ z + u ≦ 5, 10 ≦ v ≦ 15), and AE is Ca, Sr, Ba, Cu, Ag. And at least one selected from the group consisting of Au.
本発明のｐ−型およびｎ−型熱電変換材料は、充填スクッテルダイト構造を有することが望ましい。このような構造を有する熱電変換材料は、溶解法、急冷凝固法、メカニカルアロイング法（ボールミル法）、または単結晶育成法などと、ホットプレス法、加熱焼結法、放電プラズマ成型法、または熱処理法などを組み合わせることによって作製することができる。しかしながら、充填スクッテルダイト構造が得られる限り、製法としては特に上記に限定されない。
以下、具体的な合成プロセスの例について説明する。
The p-type and n-type thermoelectric conversion materials of the present invention desirably have a filled skutterudite structure. Thermoelectric conversion materials having such a structure include a melting method, a rapid solidification method, a mechanical alloying method (ball mill method), or a single crystal growth method, a hot press method, a heating sintering method, a discharge plasma molding method, or It can be manufactured by combining heat treatment methods and the like. However, as long as a filled skutterudite structure is obtained, the production method is not particularly limited to the above.
Hereinafter, a specific example of the synthesis process will be described.
本発明のｐ−およびｎ−型熱電変換材料の合成プロセスとして、溶解法と熱処理法とを組み合わせた例について説明する。所定比率で純金属の原料をアルミナ坩堝に入れ、不活性ガス雰囲気中において、電気加熱によって１２００℃まで加熱溶解する。５時間保持した後、９００℃で６時間、引き続いて８００℃で１２時間、７００℃で２４時間、さらに６００℃で１２時間保持する。その後、室温まで冷却することにより、目的の熱電変換材料を得ることができる。 As a synthesis process of the p- and n-type thermoelectric conversion materials of the present invention, an example in which a melting method and a heat treatment method are combined will be described. Pure metal raw material is put in an alumina crucible at a predetermined ratio, and is heated and melted to 1200 ° C. by electric heating in an inert gas atmosphere. After holding for 5 hours, it is held at 900 ° C. for 6 hours, subsequently at 800 ° C. for 12 hours, at 700 ° C. for 24 hours, and further at 600 ° C. for 12 hours. Then, the target thermoelectric conversion material can be obtained by cooling to room temperature.
本発明のｐ−およびｎ−型熱電変換材料の合成プロセスとして、溶解法と放電プラズマ成型法とを組み合わせた例について説明する。所定比率で純金属の原料をアルミナ坩堝に入れ、不活性ガス雰囲気中において、１２００℃まで加熱溶解する。２時間保持した後、室温まで冷却し、インゴットを得る。このインゴット原料を粉砕し、粉末をカーボンダイスに入れ、真空もしくは不活性ガス雰囲気中において、６０ＭＰａの圧力の下でパルス電流をかけながら５００〜７００℃の温度まで加熱する。１０分間保持した後、室温まで冷却することで目的の熱電変換材料を得ることができる。 As a synthesis process of the p- and n-type thermoelectric conversion materials of the present invention, an example in which a melting method and a discharge plasma molding method are combined will be described. Pure metal raw material is put in an alumina crucible at a predetermined ratio, and heated and melted to 1200 ° C. in an inert gas atmosphere. After holding for 2 hours, it cools to room temperature and obtains an ingot. The ingot raw material is pulverized, and the powder is put into a carbon die and heated to a temperature of 500 to 700 ° C. while applying a pulse current under a pressure of 60 MPa in a vacuum or an inert gas atmosphere. After holding for 10 minutes, the target thermoelectric conversion material can be obtained by cooling to room temperature.
さらに、本発明のｐ−およびｎ−型熱電変換材料の合成プロセスとして、メカニカルアロイング法と放電プラズマ成型法とを組み合わせた例について説明する。まず、不活性ガス雰囲気中において、所定比率で純金属粉末をアルミナ容器の中に入れ、アルミナボールと混合する。次いで、メカニカルアロイングを２４時間行い、原料粉末を得る。この粉末をカーボンダイスに入れ、真空もしくは不活性ガス雰囲気中において、６０ＭＰａの圧力の下でパルス電流をかけながら５００〜７００℃の温度まで加熱し、１０分間保持する。その後、室温まで冷却することにより、目的の熱電変換材料を得ることができる。 Furthermore, the example which combined the mechanical alloying method and the discharge plasma shaping | molding method is demonstrated as a synthetic | combination process of the p- and n-type thermoelectric conversion material of this invention. First, pure metal powder is put into an alumina container at a predetermined ratio in an inert gas atmosphere and mixed with alumina balls. Next, mechanical alloying is performed for 24 hours to obtain a raw material powder. This powder is put into a carbon die, heated in a vacuum or an inert gas atmosphere to a temperature of 500 to 700 ° C. while applying a pulse current under a pressure of 60 MPa, and held for 10 minutes. Then, the target thermoelectric conversion material can be obtained by cooling to room temperature.
上述した何れの製法を用いた場合も、得られた熱電変換材料は充填スクッテルダイト構造を有することが粉末Ｘ線回折によって確認された。そして、そのゼーベック係数、電気抵抗率、熱伝導率と温度との関係を測定し、無次元性能指数ＺＴの温度依存性を調べた。その結果、温度の上昇と共にＺＴが大きくなり、３００〜６００℃の温度範囲でＺＴは０．８〜１．１に達した。 It was confirmed by powder X-ray diffraction that the obtained thermoelectric conversion material had a filled skutterudite structure in any of the above-described production methods. Then, the relationship between the Seebeck coefficient, electrical resistivity, thermal conductivity and temperature was measured, and the temperature dependence of the dimensionless figure of merit ZT was investigated. As a result, ZT increased with increasing temperature, and ZT reached 0.8 to 1.1 in the temperature range of 300 to 600 ° C.
以下、実施例によって本発明を具体的に説明する。 Hereinafter, the present invention will be described specifically by way of examples.
（実施例１）
本実施例では、ｎ−型Ｙｂ０．３Ｃａ０．１Ｆｅ０．２５Ｃｏ３．７５Ｓｂ１２熱電変換材料の合成法およびその熱電性能について述べる。
(Example 1)
In this example, a synthesis method of an n-type Yb 0.3 Ca 0.1 Fe 0.25 Co 3.75 Sb 12 thermoelectric conversion material and its thermoelectric performance will be described.
原料として所定比率の純金属Ｙｂ、Ｆｅ、Ｃｏ、Ｃａ、およびＳｂをアルミナ坩堝に入れ、不活性ガス雰囲気中において、電気加熱によって１２００℃まで加熱溶解した。５時間保持した後、９００℃で６時間、引き続いて８００℃で１２時間、７００℃で２４時間、さらに６００℃で１２時間保持した。その後、室温まで冷却し、目的の熱電変換材料を得た。 Pure metals Yb, Fe, Co, Ca, and Sb in a predetermined ratio as raw materials were placed in an alumina crucible and heated and melted to 1200 ° C. by electric heating in an inert gas atmosphere. After being held for 5 hours, it was held at 900 ° C. for 6 hours, subsequently at 800 ° C. for 12 hours, at 700 ° C. for 24 hours, and further at 600 ° C. for 12 hours. Then, it cooled to room temperature and obtained the target thermoelectric conversion material.
熱電性能評価装置を用い、室温〜６００℃の温度範囲で上述の熱電変換材料のゼーベック係数、電気抵抗率および熱伝導率を測定し、無次元性能指数を算出した。図１〜図４はそれぞれ本実施例で得られたＹｂ０．３Ｃａ０．１Ｆｅ０．２５Ｃｏ３．７５Ｓｂ１２のゼーベック係数Ｓ、電気抵抗率ρ、熱伝導率κおよび無次元性能指数ＺＴと温度との関係を示す。温度の上昇につれて、ゼーベック係数の絶対値、電気抵抗率およびＺＴは大きくなった。これらの結果から、図４に示すように、本実施例のｎ−型熱電変換材料の無次元性能指数ＺＴは温度の上昇につれて大きくなり、３００℃以上の温度で０．８以上、４００℃以上の温度で１．０以上、５００℃で最大値１．１に達した。 Using a thermoelectric performance evaluation apparatus, the Seebeck coefficient, electrical resistivity, and thermal conductivity of the thermoelectric conversion material described above were measured in a temperature range of room temperature to 600 ° C., and a dimensionless figure of merit was calculated. 1 to 4 show the Seebeck coefficient S, electrical resistivity ρ, thermal conductivity κ and dimensionless performance of Yb 0.3 Ca 0.1 Fe 0.25 Co 3.75 Sb 12 obtained in this example, respectively. The relationship between the index ZT and temperature is shown. As the temperature increased, the absolute value of Seebeck coefficient, electrical resistivity, and ZT increased. From these results, as shown in FIG. 4, the dimensionless figure of merit ZT of the n-type thermoelectric conversion material of this example increases as the temperature rises, and is 0.8 or more and 400 or more at a temperature of 300 or more. The temperature reached 1.0 or more at a temperature of 1.1 and a maximum value of 1.1 at 500 ° C.
（比較例１）
本比較例では、Ｙｂ０．１５Ｃｏ４Ｓｂ１２熱電変換材料の従来溶製法およびその熱電性能について述べる。
(Comparative Example 1)
In this comparative example, a conventional melting method of Yb 0.15 Co 4 Sb 12 thermoelectric conversion material and its thermoelectric performance will be described.
Ｙｂ、Ｃｏ、Ｓｂの単体金属を出発原料とし、Ｙｂ：Ｃｏ：Ｓｂ＝１：９．０８２０：５６．２９２２の重量比率で純金属Ｙｂ、Ｃｏ、Ｓｂの原料をアルミナ坩堝に入れた。不活性ガス雰囲気中において、電気炉加熱によって液相線以上の温度まで、例えば１２００℃まで加熱・溶解し、２時間保持した。その後、徐冷し、９００℃で６時間、８００℃で２４時間、６５０℃で１２時間、さらに５５０℃で６時間それぞれ保持した。室温まで冷却することにより、Ｙｂ０．１５Ｃｏ４Ｓｂ１２熱電変換材料が得られた。 A single metal of Yb, Co, and Sb was used as a starting material, and raw materials of pure metal Yb, Co, and Sb were put in an alumina crucible at a weight ratio of Yb: Co: Sb = 1: 9.0820: 56.922. In an inert gas atmosphere, the mixture was heated and dissolved to a temperature above the liquidus, for example, 1200 ° C. by electric furnace heating, and held for 2 hours. Thereafter, it was gradually cooled and held at 900 ° C. for 6 hours, 800 ° C. for 24 hours, 650 ° C. for 12 hours, and further at 550 ° C. for 6 hours. A Yb 0.15 Co 4 Sb 12 thermoelectric conversion material was obtained by cooling to room temperature.
熱電性能評価装置を用い、室温〜６００℃の温度範囲でこの熱電変換材料のゼーベック係数、電気抵抗率および熱伝導率を測定し、無次元性能指数を算出した。これらの結果を図９〜図１２に示す。熱伝導率の最小値は３．５Ｗ／ｍＫであった。また、無次元性能指数ＺＴは３００〜５００℃の温度範囲で最大０．３５であった。 Using a thermoelectric performance evaluation apparatus, the Seebeck coefficient, electrical resistivity, and thermal conductivity of the thermoelectric conversion material were measured in a temperature range of room temperature to 600 ° C., and a dimensionless figure of merit was calculated. These results are shown in FIGS. The minimum value of thermal conductivity was 3.5 W / mK. The dimensionless figure of merit ZT was a maximum of 0.35 in the temperature range of 300 to 500 ° C.
実施例１と比較例１とを比較すると、実施例１のｎ−型Ｙｂ０．３Ｃａ０．１Ｆｅ０．２５Ｃｏ３．７５Ｓｂ１２熱電変換材料は、比較例１の高い熱電性能を有するｎ−型熱電変換材料Ｙｂ０．１５Ｃｏ４Ｓｂ１２に比べ、さらにＹｂとＣａおよびＦｅとＣｏの共存によって出力因子の値Ｐ（＝Ｓ２／ρ）が大きく、また熱伝導率が小さくなって、より一層高い熱電性能を示した。特に、比較例１のｎ−型熱電変換材料Ｙｂ０．１５Ｃｏ４Ｓｂ１２の熱伝導率の最小値は３．５Ｗ／ｍＫであったが、図３に示すように実施例１の熱電変換材料における熱伝導率の最小値は２．３Ｗ／ｍＫであった。従って、実施例１のｎ−型熱電変換材料においては、比較例１のＹｂ０．１５Ｃｏ４Ｓｂ１２材料の熱伝導率に比べて熱伝導率が大幅に低下した。図４に示すように、実施例１のｎ−型熱電変換材料の無次元性能指数ＺＴは温度の上昇につれて大きくなり、５００℃で最大値１．１に達している。 When Example 1 and Comparative Example 1 are compared, the n-type Yb 0.3 Ca 0.1 Fe 0.25 Co 3.75 Sb 12 thermoelectric conversion material of Example 1 has the high thermoelectric performance of Comparative Example 1. Compared with the n-type thermoelectric conversion material Yb 0.15 Co 4 Sb 12 , the coexistence of Yb and Ca and Fe and Co has a larger output factor value P (= S 2 / ρ) and lower thermal conductivity. Thus, even higher thermoelectric performance was exhibited. In particular, the minimum value of the thermal conductivity of the n-type thermoelectric conversion material Yb 0.15 Co 4 Sb 12 of Comparative Example 1 was 3.5 W / mK, but the thermoelectric conversion of Example 1 as shown in FIG. The minimum value of thermal conductivity in the material was 2.3 W / mK. Therefore, in the n-type thermoelectric conversion material of Example 1, the thermal conductivity was significantly reduced as compared with the thermal conductivity of the Yb 0.15 Co 4 Sb 12 material of Comparative Example 1. As shown in FIG. 4, the dimensionless figure of merit ZT of the n-type thermoelectric conversion material of Example 1 increases as the temperature increases, and reaches a maximum value of 1.1 at 500 ° C.
（実施例２）
本実施例では、ｎ−型Ｙｂ０．３Ｓｒ０．１Ｆｅ０．２５Ｃｏ３．７５Ｓｂ１２熱電変換材料の合成法およびその熱電性能について述べる。
(Example 2)
In this example, a method for synthesizing n-type Yb 0.3 Sr 0.1 Fe 0.25 Co 3.75 Sb 12 thermoelectric conversion material and its thermoelectric performance will be described.
原料として、所定比率で純金属Ｙｂ、Ｆｅ、Ｃｏ、Ｓｒ、およびＳｂを秤量し、アルミナ坩堝に入れた。これらを不活性ガス雰囲気中において、電気加熱によって１２００℃まで加熱溶解した。５時間保持した後、９００℃で６時間、引き続いて８００℃で１２時間、７００℃で２４時間、６００℃で１２時間保持した。その後、室温まで冷却し、目的のＹｂ０．３Ｓｒ０．１Ｆｅ０．２５Ｃｏ３．７５Ｓｂ１２熱電変換材料を得た。さらに熱電性能評価装置を用いて室温〜６００℃の温度範囲でこの材料における無次元性能指数を算出したところ、無次元性能指数ＺＴは４００〜6００℃の温度範囲で最大０．９に達した。
As raw materials, pure metals Yb, Fe, Co, Sr, and Sb were weighed at a predetermined ratio and placed in an alumina crucible. These were heated and dissolved up to 1200 ° C. by electric heating in an inert gas atmosphere. After holding for 5 hours, it was held at 900 ° C. for 6 hours, subsequently at 800 ° C. for 12 hours, at 700 ° C. for 24 hours, and at 600 ° C. for 12 hours. After cooling to room temperature to obtain a Yb 0.3 Sr 0.1 Fe 0.25 Co 3.75
（実施例３）
本実施例では、ｎ−型Ｙｂ０．３Ｂａ０．１Ｆｅ０．２５Ｃｏ３．７５Ｓｂ１２熱電変換材料の合成法およびその熱電性能について述べる。
(Example 3)
In this example, a synthesis method of an n-type Yb 0.3 Ba 0.1 Fe 0.25 Co 3.75 Sb 12 thermoelectric conversion material and its thermoelectric performance will be described.
原料として、所定比率で純金属Ｙｂ、Ｆｅ、Ｃｏ、Ｂａ、Ｓｂを秤量し、アルミナ坩堝に入れた。これらを不活性ガス雰囲気中において、電気加熱によって１２００℃まで加熱溶解した。５時間保持した後、９００℃で６時間、引き続いて８００℃で１２時間、７００℃で２４時間、６００℃で１２時間保持した。その後、室温まで冷却し、目的のＹｂ０．３Ｂａ０．１Ｆｅ０．２５Ｃｏ３．７５Ｓｂ１２熱電変換材料を得た。さらに熱電性能評価装置を用いて室温〜６００℃の温度範囲でこの材料における無次元性能指数を算出したところ、無次元性能指数ＺＴは４００〜６００℃の温度範囲で最大１．０に達した。
As raw materials, pure metals Yb, Fe, Co, Ba, and Sb were weighed at a predetermined ratio and placed in an alumina crucible. These were heated and dissolved to 1200 ° C. by electric heating in an inert gas atmosphere. After holding for 5 hours, it was held at 900 ° C. for 6 hours, subsequently at 800 ° C. for 12 hours, at 700 ° C. for 24 hours, and at 600 ° C. for 12 hours. After cooling to room temperature to obtain a Yb 0.3 Ba 0.1 Fe 0.25 Co 3.75
（実施例４）
本実施例では、ｎ−型Ｙｂ０．４Ａｇ０．１Ｆｅ０．７５Ｃｏ３．２５Ｓｂ１２熱電変換材料の合成法およびその熱電性能について述べる。
Example 4
In this example, a synthesis method of an n-type Yb 0.4 Ag 0.1 Fe 0.75 Co 3.25 Sb 12 thermoelectric conversion material and its thermoelectric performance will be described.
原料として、所定比率で純金属Ｙｂ、Ｆｅ、Ｃｏ、Ａｇ、およびＳｂを秤量し、アルミナ坩堝に入れ、不活性ガス雰囲気中において、電気加熱によって１２００℃まで加熱溶解した。これらを５時間保持した後、９００℃で６時間、引き続いて８００℃で１２時間、７００℃で２４時間、６００℃で１２時間保持した。その後、室温まで冷却し、目的のＹｂ０．４Ａｇ０．１Ｆｅ０．７５Ｃｏ３．２５Ｓｂ１２熱電変換材料を得た。さらに熱電性能評価装置を用いて室温〜６００℃の温度範囲でこの材料における無次元性能指数を算出したところ、無次元性能指数ＺＴは４００〜６００℃の温度範囲で最大１．０に達した。
Pure metals Yb, Fe, Co, Ag, and Sb were weighed as raw materials at a predetermined ratio, placed in an alumina crucible, and heated and melted to 1200 ° C. by electric heating in an inert gas atmosphere. These were held for 5 hours, then at 900 ° C. for 6 hours, followed by 800 ° C. for 12 hours, 700 ° C. for 24 hours, and 600 ° C. for 12 hours. After cooling to room temperature to obtain a Yb 0.4 Ag 0.1 Fe 0.75 Co 3.25
（実施例５）
本実施例では、ｎ−型Ｙｂ０．３Ｃａ０．１Ｆｅ０．２５Ｃｏ３．７５Ｓｂ１１．５熱電変換材料の合成法およびその熱電性能について述べる。
原料として、所定比率で純金属Ｙｂ、Ｆｅ、Ｃｏ、Ｃａ、Ｓｂを秤量し、アルミナ坩堝に入れ、不活性ガス雰囲気中において、電気加熱によって１２００℃まで加熱溶解した。これらを５時間保持した後、９００℃で６時間、引き続いて８００℃で１２時間、７００℃で２４時間、６００℃で１２時間保持した。その後、室温まで冷却し、目的のＹｂ０．３Ｃａ０．１Ｆｅ０．２５Ｃｏ３．７５Ｓｂ１１．５熱電変換材料を得た。さらに熱電性能評価装置を用いて室温〜６００℃の温度範囲でこの材料における無次元性能指数を算出したところ、無次元性能指数ＺＴは４００〜６００℃の温度範囲で最大１．０に達した。
(Example 5)
In this example, a method of synthesizing an n-type Yb 0.3 Ca 0.1 Fe 0.25 Co 3.75 Sb 11.5 thermoelectric conversion material and its thermoelectric performance will be described.
Pure metals Yb, Fe, Co, Ca, and Sb were weighed as raw materials at a predetermined ratio, put in an alumina crucible, and heated and melted to 1200 ° C. by electric heating in an inert gas atmosphere. These were held for 5 hours, then at 900 ° C. for 6 hours, followed by 800 ° C. for 12 hours, 700 ° C. for 24 hours, and 600 ° C. for 12 hours. After cooling to room temperature to obtain a Yb 0.3 Ca 0.1 Fe 0.25 Co 3.75 Sb 11.5 thermoelectric conversion material of interest. Furthermore, when the dimensionless figure of merit in this material was calculated in the temperature range of room temperature to 600 ° C. using a thermoelectric performance evaluation apparatus, the dimensionless figure of merit ZT reached a maximum of 1.0 in the temperature range of 400 to 600 ° C.
（実施例６）
本実施例では、ｐ−型Ｙｂ０．７５Ａｇ０．０５Ｆｅ２Ｃｏ２Ｓｂ１２熱電変換材料の合成法およびその熱電性能について述べる。
(Example 6)
In this example, a method for synthesizing a p-type Yb 0.75 Ag 0.05 Fe 2 Co 2 Sb 12 thermoelectric conversion material and its thermoelectric performance will be described.
原料として、所定比率で純金属Ｙｂ、Ｆｅ、Ｃｏ、Ａｇ、およびＳｂをアルミナ坩堝に入れ、不活性ガス雰囲気中において、電気炉加熱によって１２００℃まで加熱溶解した。これらを５時間保持した後、９００℃で６時間、引き続いて８００℃で１２時間、７００℃で２４時間、さらに６００℃で１２時間保持した。その後、室温まで冷却し、目的の熱電変換材料を得た。 Pure metals Yb, Fe, Co, Ag, and Sb as raw materials were put in an alumina crucible at a predetermined ratio, and heated and melted to 1200 ° C. by heating in an electric furnace in an inert gas atmosphere. These were held for 5 hours, then at 900 ° C. for 6 hours, subsequently at 800 ° C. for 12 hours, at 700 ° C. for 24 hours, and further at 600 ° C. for 12 hours. Then, it cooled to room temperature and obtained the target thermoelectric conversion material.
熱電性能評価装置を用い、室温〜６００℃の温度範囲で上述の熱電変換材料のゼーベック係数、電気抵抗率および熱伝導率を測定し、無次元性能指数を算出した。これらの結果を図５〜図８に示す。ＹｂとＡｇおよびＦｅとＣｏの二重共存によって熱伝導率の値はかなり小さくなった。図７に示すように、５００℃以下の温度範囲で熱伝導率の値は２Ｗ／ｍＫ以下となり、その最小値は１．４Ｗ／ｍＫであった。熱伝導率が小さくなったため、無次元性能指数ＺＴが大きくなり、その最大値は０．８に達した。 Using a thermoelectric performance evaluation apparatus, the Seebeck coefficient, electrical resistivity, and thermal conductivity of the thermoelectric conversion material described above were measured in a temperature range of room temperature to 600 ° C., and a dimensionless figure of merit was calculated. These results are shown in FIGS. Due to the double coexistence of Yb and Ag and Fe and Co, the value of thermal conductivity became considerably small. As shown in FIG. 7, the thermal conductivity value was 2 W / mK or less in the temperature range of 500 ° C. or less, and the minimum value was 1.4 W / mK. Since the thermal conductivity was reduced, the dimensionless figure of merit ZT was increased, and the maximum value reached 0.8.
（実施例７）
本実施例では、ｐ−型Ｙｂ０．７５Ｃａ０．１Ｆｅ２．５Ｃｏ１．５Ｓｂ１２熱電変換材料の合成法およびその熱電性能について述べる。
(Example 7)
In this example, a method for synthesizing a p-type Yb 0.75 Ca 0.1 Fe 2.5 Co 1.5 Sb 12 thermoelectric conversion material and its thermoelectric performance will be described.
原料として、所定比率の純金属Ｙｂ、Ｆｅ、Ｃｏ、Ｃａ、およびＳｂを秤量し、アルミナ坩堝に入れ、不活性ガス雰囲気中において、電気加熱によって１２００℃まで加熱溶解した。これらを５時間保持した後、９００℃で６時間、引き続いて８００℃で１２時間、７００℃で２４時間、６００℃で１２時間保持した。その後、室温まで冷却し、目的のＹｂ０．７５Ｃａ０．１Ｆｅ２．５Ｃｏ１．５Ｓｂ１２熱電変換材料を得た。熱電性能評価装置を用いて室温〜６００℃の温度範囲でこの材料における無次元性能指数を算出したところ、無次元性能指数ＺＴは４００〜６００℃の温度範囲で最大０．８に達した。
As raw materials, pure metals Yb, Fe, Co, Ca, and Sb at a predetermined ratio were weighed, put into an alumina crucible, and heated and melted to 1200 ° C. by electric heating in an inert gas atmosphere. These were held for 5 hours, then at 900 ° C. for 6 hours, followed by 800 ° C. for 12 hours, 700 ° C. for 24 hours, and 600 ° C. for 12 hours. After cooling to room temperature to obtain a Yb 0.75 Ca 0.1 Fe 2.5 Co 1.5
（実施例８）
本実施例では、ｐ−型Ｙｂ０．７５Ｃａ０．１Ｆｅ２．５Ｃｏ１．５Ｓｂ１１熱電変換材料の合成法およびその熱電性能について述べる。
(Example 8)
In this example, a method for synthesizing a p-type Yb 0.75 Ca 0.1 Fe 2.5 Co 1.5 Sb 11 thermoelectric conversion material and its thermoelectric performance will be described.
原料として、所定比率の純金属Ｙｂ、Ｆｅ、Ｃｏ、Ｃａ、およびＳｂを秤量し、アルミナ坩堝に入れ、不活性ガス雰囲気中において、電気加熱によって１２００℃まで加熱溶解した。これらを５時間保持した後、９００℃で６時間、引き続いて８００℃で１２時間、７００℃で２４時間、６００℃で１２時間保持した。その後、室温まで冷却し、目的のＹｂ０．７５Ｃａ０．１Ｆｅ２．５Ｃｏ１．５Ｓｂ１１熱電変換材料を得た。熱電性能評価装置を用いて室温〜６００℃の温度範囲でこの材料における無次元性能指数を算出したところ、無次元性能指数ＺＴは４００〜６００℃の温度範囲で最大０．８に達した。 As raw materials, pure metals Yb, Fe, Co, Ca, and Sb at a predetermined ratio were weighed, put into an alumina crucible, and heated and melted to 1200 ° C. by electric heating in an inert gas atmosphere. These were held for 5 hours, then at 900 ° C. for 6 hours, followed by 800 ° C. for 12 hours, 700 ° C. for 24 hours, and 600 ° C. for 12 hours. After cooling to room temperature to obtain a Yb 0.75 Ca 0.1 Fe 2.5 Co 1.5 Sb 11 thermoelectric conversion material of interest. When the dimensionless figure of merit in this material was calculated in the temperature range of room temperature to 600 ° C. using a thermoelectric performance evaluation apparatus, the dimensionless figure of merit ZT reached a maximum of 0.8 in the temperature range of 400 to 600 ° C.
以上の結果から明らかなように、本発明によるｐ−型およびｎ−型ＹｂｘＡＥｙＦｅｚＣｏｕＳｂｖ（０＜ｘ≦１、０＜ｙ≦１、０＜ｘ+ｙ≦１、０≦ｚ≦４、０≦ｕ≦４、３≦ｚ+ｕ≦５、１０≦ｖ≦１５、ＡＥはＣａ、Ｓｒ、Ｂａ、Ｃｕ、Ａｇ、およびＡｕからなる群から選択される少なくとも一種）熱電変換材料は無次元性能指数ＺＴ＝０．８〜１．１に達し、従来の熱電変換材料よりも優れた熱電性能を有する。 More As is apparent from the results, according to the invention p- type and n- type Yb x AE y Fe z Co u Sb v (0 <x ≦ 1,0 <y ≦ 1,0 <x + y ≦ 1, 0 ≦ z ≦ 4, 0 ≦ u ≦ 4, 3 ≦ z + u ≦ 5, 10 ≦ v ≦ 15, AE is at least one selected from the group consisting of Ca, Sr, Ba, Cu, Ag, and Au) The thermoelectric conversion material reaches a dimensionless figure of merit ZT = 0.8 to 1.1 and has a thermoelectric performance superior to that of conventional thermoelectric conversion materials.
さらに、ＹｂｘＡＥｙＦｅｚＣｏｕＳｂｖの中のＣｏおよび／またはＦｅの一部分をＲｕ、Ｏｓ、Ｒｈ、Ｉｒ、Ｎｉ、Ｐｄ、およびＰｔからなる群から選択される少なくとも一種で置換した場合、これらの元素がＣｏおよび／またはＦｅの格子サイトに取りこまれ、異なる元素の混在によってフォノン散乱が引き起こされる。その結果、熱伝導率の値は置換前より小さくなる。これにより熱電性能がより一層高くなる。実施例を用いて以下に具体的に説明する。 Furthermore, Yb x AE y Fe z Co u Sb v part of Co and / or Fe in the Ru, Os, Rh, Ir, Ni, when substituted by at least one selected from the group consisting of Pd, and Pt These elements are incorporated into Co and / or Fe lattice sites, and phonon scattering is caused by the mixture of different elements. As a result, the value of thermal conductivity is smaller than before replacement. This further increases the thermoelectric performance. This will be specifically described below with reference to examples.
（実施例９）
本実施例では、ｎ−型Ｙｂ０．３Ｓｒ０．１Ｆｅ０．２５Ｃｏ３．７Ｒｈ０．０５Ｓｂ１２熱電変換材料の合成法およびその熱電性能について述べる。
Example 9
In this example, a method for synthesizing an n-type Yb 0.3 Sr 0.1 Fe 0.25 Co 3.7 Rh 0.05 Sb 12 thermoelectric conversion material and its thermoelectric performance will be described.
原料として、所定比率の純金属Ｙｂ、Ｆｅ、Ｃｏ、Ｒｈ、Ｓｒ、およびＳｂを秤量し、アルミナ坩堝に入れ、不活性ガス雰囲気中において、電気加熱によって１２００℃まで加熱溶解した。これらを５時間保持した後、９００℃で６時間、引き続いて８００℃で１２時間、７００℃で２４時間、６００℃で１２時間保持した。その後、室温まで冷却し、目的のＹｂ０．３Ｓｒ０．１Ｆｅ０．２５Ｃｏ３．７Ｒｈ０．０５Ｓｂ１２熱電変換材料を得た。
さらに熱電性能評価装置を用いて室温〜６００℃の温度範囲でこの材料の熱電性能を評価した。その結果、実施例２で得られたｎ−型Ｙｂ０．３Ｓｒ０．１Ｆｅ０．２５Ｃｏ３．７５Ｓｂ１２熱電変換材料に比べ、ゼーベック係数と電気抵抗率はあまり変わっていないが、熱伝導率は小さくなった。例えば、５００℃において、ＲｈでＣｏを置換していないｎ−型Ｙｂ０．３Ｓｒ０．１Ｆｅ０．２５Ｃｏ３．７５Ｓｂ１２熱電変換材料のゼーベック係数、電気抵抗率および熱伝導率は、それぞれ−１９０μＶ／Ｋ、１．１×１０−５Ωm、２．８Ｗ／ｍＫであったが、置換後のｎ−型Ｙｂ０．３Ｓｒ０．１Ｆｅ０．２５Ｃｏ３．７Ｒｈ０．０５Ｓｂ１２熱電変換材料においては、それぞれ−１８５μＶ／Ｋ、１．０×１０−５Ωm、２．５Ｗ／ｍＫとなり、熱伝導率の値は約１０％小さくなった。その結果、実施例２で得られた熱電変換材料の無次元性能指数ＺＴの最大値は０．９であるが、本実施例で得られた熱電変換材料の無次元性能指数ＺＴの最大値は１．０に達した。これはＹｂｘＡＥｙＦｅｚＣｏｕＳｂｖの中にＣｏあるいはＦｅの一部分をＲｕ、Ｏｓ、Ｒｈ、Ｉｒ、Ｎｉ、Ｐｄ、およびＰｔからなる群から選択される少なくとも一種の元素で置換して、熱電性能を向上できることを示している。
As raw materials, pure metals Yb, Fe, Co, Rh, Sr, and Sb in a predetermined ratio were weighed, put into an alumina crucible, and heated and melted to 1200 ° C. by electric heating in an inert gas atmosphere. These were held for 5 hours, then at 900 ° C. for 6 hours, followed by 800 ° C. for 12 hours, 700 ° C. for 24 hours, and 600 ° C. for 12 hours. After cooling to room temperature to obtain a Yb 0.3 Sr 0.1 Fe 0.25 Co 3.7 Rh 0.05
Furthermore, the thermoelectric performance of this material was evaluated in the temperature range of room temperature to 600 ° C. using a thermoelectric performance evaluation apparatus. As a result, the Seebeck coefficient and the electrical resistivity are not significantly changed as compared with the n-type Yb 0.3 Sr 0.1 Fe 0.25 Co 3.75 Sb 12 thermoelectric conversion material obtained in Example 2. The thermal conductivity decreased. For example, at 500 ° C., the Seebeck coefficient, electrical resistivity, and thermal conductivity of an n-type Yb 0.3 Sr 0.1 Fe 0.25 Co 3.75 Sb 12 thermoelectric conversion material in which Co is not substituted with Rh are: Were −190 μV / K, 1.1 × 10 −5 Ωm, and 2.8 W / mK, respectively, but after replacement, n-type Yb 0.3 Sr 0.1 Fe 0.25 Co 3.7 Rh 0 In the .05 Sb 12 thermoelectric conversion material, the values were −185 μV / K, 1.0 × 10 −5 Ωm, and 2.5 W / mK, respectively, and the values of thermal conductivity were reduced by about 10%. As a result, the maximum value of the dimensionless figure of merit ZT of the thermoelectric conversion material obtained in Example 2 is 0.9, but the maximum value of the dimensionless figure of merit ZT of the thermoelectric conversion material obtained in this example is Reached 1.0. It replaced a portion of the Co or Fe in the Yb x AE y Fe z Co u Sb v Ru, Os, Rh, Ir, Ni, at least one element selected from the group consisting of Pd, and Pt This indicates that the thermoelectric performance can be improved.
（実施例１０）
本実施例では、ｐ−型Ｙｂ０．７５Ａｇ０．０５Ｆｅ１．９５Ｒｕ０．０５Ｃｏ２Ｓｂ１２熱電変換材料の合成法、熱電性能およびＲｕによるＦｅの部分置換効果について述べる。
(Example 10)
In this example, a method for synthesizing a p-type Yb 0.75 Ag 0.05 Fe 1.95 Ru 0.05 Co 2 Sb 12 thermoelectric conversion material, thermoelectric performance, and effect of partial substitution of Fe by Ru will be described.
原料として、所定比率の純金属Ｙｂ、Ｆｅ、Ｒｕ、Ｃｏ、Ａｇ、Ｓｂをアルミナ坩堝に入れ、不活性ガス雰囲気中において、電気炉加熱によって１２００℃まで加熱溶解した。これらを５時間保持した後、９００℃で６時間、引き続いて８００℃で１２時間、７００℃で２４時間、さらに６００℃で１２時間保持した。その後、室温まで冷却し、目的のＹｂ０．７５Ａｇ０．０５Ｆｅ１．９５Ｒｕ０．０５Ｃｏ２Ｓｂ１２熱電変換材料を得た。
さらに熱電性能評価装置を用いて室温〜６００℃の温度範囲で本実施例で得た熱電変換材料における無次元性能指数を算出したところ、無次元性能指数ＺＴは４００〜６００℃の温度範囲で最大０．８５に達した。無次元性能指数ＺＴの最大値が０．８である、ＲｕでＦｅを置換していない実施例６のｐ−型Ｙｂ０．７５Ａｇ０．０５Ｆｅ２Ｃｏ２Ｓｂ１２熱電変換材料に比べ、本実施例の熱電変換材料は無次元性能指数ＺＴが向上されている。従って、ＲｕによるＦｅの部分置換は熱電性能を向上させることが分かった。
As a raw material, pure metals Yb, Fe, Ru, Co, Ag, and Sb in a predetermined ratio were put in an alumina crucible, and heated and melted to 1200 ° C. by heating in an electric furnace in an inert gas atmosphere. These were held for 5 hours, then at 900 ° C. for 6 hours, subsequently at 800 ° C. for 12 hours, at 700 ° C. for 24 hours, and further at 600 ° C. for 12 hours. After cooling to room temperature to obtain a Yb 0.75 Ag 0.05 Fe 1.95 Ru 0.05
Furthermore, when the dimensionless figure of merit in the thermoelectric conversion material obtained in this example was calculated in the temperature range of room temperature to 600 ° C. using a thermoelectric performance evaluation apparatus, the dimensionless figure of merit ZT was the maximum in the temperature range of 400 to 600 ° C. It reached 0.85. Compared to the p-type Yb 0.75 Ag 0.05 Fe 2 Co 2 Sb 12 thermoelectric conversion material of Example 6 in which the maximum value of the dimensionless figure of merit ZT is 0.8 and Fe is not substituted with Ru, The thermoelectric conversion material of this example has an improved dimensionless figure of merit ZT. Therefore, it was found that partial substitution of Fe with Ru improves thermoelectric performance.
以上、実施の形態および実施例を用いて本発明を詳細に説明したが、本発明は上記内容に限定されるものではなく、本発明の範疇を逸脱しない範囲においてあらゆる変形や変更が可能である。 Although the present invention has been described in detail with reference to the embodiments and examples, the present invention is not limited to the above contents, and various modifications and changes can be made without departing from the scope of the present invention. .
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| JP2011510479A (en) * | 2007-12-19 | 2011-03-31 | バイオメトリック・テクノロジー・ソリューションズ・リミテッド | Method for producing thermoelectric intermetallic compound |
| EP2896473A1 (en) | 2014-01-16 | 2015-07-22 | Kabushiki Kaisha Toyota Chuo Kenkyusho | N-type thermoelectric material |
| JP2018148114A (en) * | 2017-03-08 | 2018-09-20 | 株式会社豊田中央研究所 | p-type thermoelectric material |
| JP2018157002A (en) * | 2017-03-16 | 2018-10-04 | 古河機械金属株式会社 | Thermoelectric conversion material |
| US10790428B2 (en) | 2015-11-11 | 2020-09-29 | Lg Chem, Ltd. | P-type skutterudite thermoelectric material, method for preparing the same, and thermoelectric device including the same |
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| JP2001135865A (en) * | 1999-11-04 | 2001-05-18 | Yamaguchi Industrial Promotion Foundation | Thermoelectric conversion material and manufacturing method for it |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2011510479A (en) * | 2007-12-19 | 2011-03-31 | バイオメトリック・テクノロジー・ソリューションズ・リミテッド | Method for producing thermoelectric intermetallic compound |
| EP2896473A1 (en) | 2014-01-16 | 2015-07-22 | Kabushiki Kaisha Toyota Chuo Kenkyusho | N-type thermoelectric material |
| JP2015156476A (en) * | 2014-01-16 | 2015-08-27 | 株式会社豊田中央研究所 | n-type thermoelectric material |
| US9478724B2 (en) | 2014-01-16 | 2016-10-25 | Kabushiki Kaisha Toyota Chuo Kenkyusho | N-type thermoelectric material |
| US10790428B2 (en) | 2015-11-11 | 2020-09-29 | Lg Chem, Ltd. | P-type skutterudite thermoelectric material, method for preparing the same, and thermoelectric device including the same |
| JP2018148114A (en) * | 2017-03-08 | 2018-09-20 | 株式会社豊田中央研究所 | p-type thermoelectric material |
| JP2018157002A (en) * | 2017-03-16 | 2018-10-04 | 古河機械金属株式会社 | Thermoelectric conversion material |
| CN113903853A (en) * | 2021-03-04 | 2022-01-07 | 杭州安誉科技有限公司 | Semiconductor refrigerating sheet and application thereof in real-time fluorescent quantitative PCR instrument |
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