JP4479628B2 - Thermoelectric material, manufacturing method thereof, and thermoelectric module - Google Patents

Thermoelectric material, manufacturing method thereof, and thermoelectric module Download PDF

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JP4479628B2
JP4479628B2 JP2005251132A JP2005251132A JP4479628B2 JP 4479628 B2 JP4479628 B2 JP 4479628B2 JP 2005251132 A JP2005251132 A JP 2005251132A JP 2005251132 A JP2005251132 A JP 2005251132A JP 4479628 B2 JP4479628 B2 JP 4479628B2
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林　　高廣
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本発明は、ペルチェ効果を利用したペルチェモジュールに使用される熱電材料及びその製造方法、並びにこの熱電材料を使用した熱電モジュールに関する。   The present invention relates to a thermoelectric material used in a Peltier module utilizing the Peltier effect, a method for manufacturing the thermoelectric material, and a thermoelectric module using the thermoelectric material.

ペルチェ効果を利用した熱電モジュールは、無音及び無振動で動作し、メンテナンスが不要であることから、小型冷蔵庫及び半導体装置内部の温度調整器等の様々な分野への適用が検討されている。このような熱電モジュールに使用される熱電材料の特性は、そのゼーベック係数をα（Ｖ／Ｋ）、比抵抗をρ（Ω・ｍ）、熱伝導率をκ（Ｗ／ｍ・Ｋ）としたとき、下記数式１に示す性能指数Ｚによって評価することができる。そして、この性能指数Ｚが高い熱電材料ほど、熱電性能が優れている。   Thermoelectric modules using the Peltier effect operate without sound and without vibration, and do not require maintenance. Therefore, application to various fields such as a small refrigerator and a temperature controller inside a semiconductor device has been studied. The characteristics of the thermoelectric material used in such a thermoelectric module are that the Seebeck coefficient is α (V / K), the specific resistance is ρ (Ω · m), and the thermal conductivity is κ (W / m · K). In this case, it can be evaluated by the figure of merit Z shown in the following formula 1. And the thermoelectric material with a higher figure of merit Z has better thermoelectric performance.

Figure 0004479628
Figure 0004479628

上記数式１に示すように、熱電材料の性能指数Ｚを高くするためには、熱伝導率κを低くすることが有効である。そこで、従来、熱電材料の熱伝導率κを低くするため、結晶粒径を小さくする方法、キャリア濃度を低減する方法等が検討されている（例えば、特許文献１乃至３参照。）。特許文献１に記載の熱電材料は、Ｂｉ及びＳｂからなる群から選択された少なくとも１種の元素と、Ｓ、Ｔｅ及びＳｅからなる群から選択された少なくとも１種の元素とを含む熱電材料に、更に、遷移金属元素及び／又は希土類金属元素、具体的には、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、Ｚｒ、Ｎｂ、Ｍｏ、Ｙ、Ｌａ、Ｃｅ、Ｎｄ、Ｓｍ及びＭｍ（ミッシュメタル）からなる群から選択された少なくとも１種の元素を添加することにより、アモルファス化又は微結晶化を促進し、熱伝導率κを低くしている。   As shown in the above formula 1, in order to increase the figure of merit Z of the thermoelectric material, it is effective to decrease the thermal conductivity κ. Therefore, in order to reduce the thermal conductivity κ of thermoelectric materials, methods for reducing the crystal grain size, methods for reducing the carrier concentration, and the like have been studied (for example, see Patent Documents 1 to 3). The thermoelectric material described in Patent Document 1 is a thermoelectric material containing at least one element selected from the group consisting of Bi and Sb and at least one element selected from the group consisting of S, Te, and Se. Furthermore, transition metal elements and / or rare earth metal elements, specifically, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Y, La, Ce, Nd, By adding at least one element selected from the group consisting of Sm and Mm (Misch metal), amorphization or microcrystallization is promoted, and the thermal conductivity κ is lowered.

また、特許文献２には、Ｂｉ及びＳｂからなる群から選択された少なくとも１種の元素と、Ｔｅ及びＳｅからなる群から選択された少なくとも１種の元素とを含む原料を、液体急冷法により薄膜又は粉末状とし、これを更に粉砕した粉末を、結晶が粗大化しない条件で放電プラズマ焼結して固化成形することにより、結晶組織を微細化する熱電冷却用材料の製造方法が提案されている。   Patent Document 2 discloses a raw material containing at least one element selected from the group consisting of Bi and Sb and at least one element selected from the group consisting of Te and Se by a liquid quenching method. A method for producing a thermoelectric cooling material that refines the crystal structure by forming a thin film or a powder and further pulverizing this powder by spark plasma sintering under the condition that the crystal does not become coarse has been proposed. Yes.

更に、特許文献３には、Ｂｉ、Ｔｅ、Ｓｂ及びＳｅからなる群から選択された少なくとも２種の元素からなる原料粉末を成形した後、０．９ＧＨｚ以上のマイクロ波により加熱焼成する熱電素子の製造方法が提案されている。この熱電素子の製造方法では、結晶粒子を粒成長させることなく焼結することができるため、熱電材料の結晶粒を微細化することができる。   Further, Patent Document 3 discloses a thermoelectric element in which a raw material powder composed of at least two elements selected from the group consisting of Bi, Te, Sb, and Se is molded and then heated and fired with a microwave of 0.9 GHz or more. Manufacturing methods have been proposed. In this method for manufacturing a thermoelectric element, the crystal grains of the thermoelectric material can be miniaturized because the crystal grains can be sintered without growing the grains.

特開平８−１１１５４６号公報JP-A-8-111546 特開平１０−４１５５４号公報JP 10-41554 A 特開２００２−２３２０２４号公報JP 2002-232024 A

しかしながら、前述の従来の技術には以下に示す問題点がある。熱電材料における熱伝導率κは、比抵抗ρとの相関が極めて強く、特許文献１乃至３のように、結晶粒径を小さくして熱伝導率κを低くした場合、キャリア移動度が低下して比抵抗ρが増加し、性能指数Ｚを効果的に向上させることができないという問題点がある。同様に、キャリア濃度を低減して熱伝導率κを低くした場合も、比抵抗ρが増加するため、性能指数Ｚを効果的に向上させることができないという問題点がある。   However, the conventional techniques described above have the following problems. The thermal conductivity κ in the thermoelectric material has an extremely strong correlation with the specific resistance ρ. When the crystal grain size is reduced and the thermal conductivity κ is lowered as in Patent Documents 1 to 3, the carrier mobility decreases. As a result, the specific resistance ρ increases and the figure of merit Z cannot be effectively improved. Similarly, even when the carrier concentration is reduced and the thermal conductivity κ is lowered, the specific resistance ρ increases, so that the figure of merit Z cannot be effectively improved.

また、Ｂｉ２Ｔｅ３系熱電材料は、比抵抗ρが、結晶構造のＣ軸方向は高く、Ａ軸方向は低いため、その結晶異方性を利用し、結晶方位を整列させた状態でＡ軸方向に通電することにより、比抵抗ρを低減して性能指数Ｚを高くすることができるが、Ｂｉ２Ｔｅ３系熱電材料の熱伝導率κはＡ軸方向が高いため、この方法でも性能指数Ｚを効果的に向上させることはできないという問題点がある。 In addition, the Bi 2 Te 3 series thermoelectric material has a specific resistance ρ, which is high in the C-axis direction and low in the A-axis direction of the crystal structure. By energizing in the axial direction, the specific resistance ρ can be reduced and the figure of merit Z can be increased. However, since the thermal conductivity κ of the Bi 2 Te 3 series thermoelectric material is high in the A-axis direction, this method also has performance. There is a problem that the index Z cannot be improved effectively.

本発明はかかる問題点に鑑みてなされたものであって、比抵抗ρを増加させずに熱伝導率κを低くすることができる熱電材料及びその製造方法並びに熱電モジュールを提供することを目的とする。   The present invention has been made in view of such problems, and an object thereof is to provide a thermoelectric material, a method for manufacturing the thermoelectric material, and a thermoelectric module that can reduce the thermal conductivity κ without increasing the specific resistance ρ. To do.

本願第１発明に係る熱電材料は、ＡをＢｉ及びＳｂからなる群から選択された少なくとも１種の元素としたとき、Ａ２ＴｅｘＳｅ３−ｘで表される組成を有する六方晶系の熱電材料において、マイクロ波焼結法により固化成形され、６ｃサイトのＴｅの一部がＳｅで置換され、Ｓｅが６ｃサイトと３ａサイトに存在する結晶構造を有し、全Ｓｅ量に対して、６ｃサイトに位置しているＳｅの割合が５１原子％以上であることを特徴とする。 The thermoelectric material according to the first invention of the present application is a hexagonal system having a composition represented by A 2 Te x Se 3-x when A is at least one element selected from the group consisting of Bi and Sb. In thermoelectric material, solidified by microwave sintering method , part of Te at 6c site is replaced by Se, Se has a crystal structure existing at 6c site and 3a site, and with respect to the total amount of Se, The ratio of Se located in the 6c site is 51 atomic% or more.

本発明においては、３ａサイトのＴｅだけでなく、６ｃサイトのＴｅの一部もＳｅで置換されているため、結晶格子が歪み、フォノン散乱の効果により、比抵抗ρを増加させずに熱伝導率κを低くすることができる。   In the present invention, not only the Te at the 3a site but also a part of the Te at the 6c site is substituted with Se, so that the crystal lattice is distorted and the heat conduction without increasing the specific resistance ρ due to the effect of phonon scattering. The rate κ can be lowered.

全Ｓｅ量に対して、６ｃサイトに位置しているＳｅの割合を５１原子％以上としたので、熱伝導率κを１５％以上低減することができ、性能指数Ｚを３．０以上にすることができる。 Since the ratio of Se located at the 6c site with respect to the total amount of Se is set to 51 atomic% or more, the thermal conductivity κ can be reduced by 15% or more, and the figure of merit Z is set to 3.0 or more. be able to.

本願第２発明に係る熱電材料の製造方法は、ＡをＢｉ及びＳｂからなる群から選択された少なくとも１種の元素としたとき、Ａ２ＴｅｘＳｅ３−ｘで表される組成の粉末及び／又は箔片を液体急冷法により冷却速度を１×１０３Ｋ／秒以上にして作製する工程と、前記粉末及び／又は箔片を、焼結時間をｔ（分）とし、焼結温度をＴ（℃）としたとき、下記数式２で表される条件で、マイクロ波焼結法により固化成形する工程と、を有し、Ａ２ＴｅｘＳｅ３−ｘで表される組成で、６ｃサイトのＴｅの一部がＳｅで置換され、Ｓｅが６ｃサイトと３ａサイトに存在する結晶構造を有し、全Ｓｅ量に対して、６ｃサイトに位置しているＳｅの割合が５１原子％以上である六方晶系熱電材料を製造することを特徴とする。 In the method for producing a thermoelectric material according to the second invention of the present application, when A is at least one element selected from the group consisting of Bi and Sb, a powder having a composition represented by A 2 Te x Se 3-x and And / or a step of producing a foil piece by a liquid quenching method at a cooling rate of 1 × 10 3 K / second or more, and the powder and / or the foil piece is set to a sintering time t (minutes), and the sintering temperature is set to When T (° C.), a step of solidifying and molding by a microwave sintering method under the conditions represented by the following mathematical formula 2, and a composition represented by A 2 Te x Se 3-x , 6c Part of Te at the site is replaced with Se, and Se has a crystal structure existing at the 6c site and the 3a site, and the ratio of Se located at the 6c site is 51 atomic% or more with respect to the total amount of Se A hexagonal thermoelectric material is produced.

Figure 0004479628
Figure 0004479628

本発明においては、液体急冷法により冷却速度を１×１０３Ｋ／秒以上にして作製した粉末及び／又は箔片を、上記数式２で表される条件で固化成形しているため、液体急冷法で急冷凝固させたときに生じた結晶構造が固化成形後も保持され、６ｃサイトのＴｅの一部がＳｅで置換された結晶構造をもつ熱電材料を製造することができる。これにより、比抵抗ρを増加させずに熱伝導率κを低くすることができ、従来の熱電材料よりも、性能指数Ｚが高い熱電材料が得られる。 In the present invention, since the powder and / or foil pieces produced at a cooling rate of 1 × 10 3 K / second or more by the liquid quenching method are solidified and molded under the conditions expressed by the above formula 2, the liquid quenching is performed. A thermoelectric material having a crystal structure in which the crystal structure generated when rapidly solidified by the method is retained after solidification and a part of Te at the 6c site is substituted with Se can be produced. Thereby, thermal conductivity (kappa) can be made low, without increasing specific resistance (rho), and the thermoelectric material whose performance index Z is higher than the conventional thermoelectric material is obtained.

この熱電材料の製造方法においては、焼結温度Ｔを（−１８．８×ｔ＋５７８．１）℃未満にして固化成形しているので、６ｃサイトにおけるＳｅ含有率を５１原子％以上にすることができるため、性能指数Ｚを３．０以上にすることができる。 In this method for producing a thermoelectric material, since the sintering temperature T is set to less than (−18.8 × t + 578.1) ° C. and solidified, the Se content at the 6c site should be 51 atomic% or more. Therefore, the figure of merit Z can be 3.0 or more.

また、前記粉末及び／又は箔片は、マイクロ波焼結法又は通電加熱焼結法により固化成形することができる。   The powder and / or the foil piece can be solidified and formed by a microwave sintering method or an electric heating sintering method.

本願第３発明に係る熱電モジュールは、前述の熱電材料が組み込まれていることを特徴とする。   The thermoelectric module according to the third invention of the present application is characterized in that the thermoelectric material described above is incorporated.

本発明においては、ＡをＢｉ及びＳｂからなる群から選択された少なくとも１種の元素としたとき、Ａ２ＴｅｘＳｅ３−ｘで表される組成で、且つ６ｃサイトのＴｅの一部がＳｅで置換された結晶構造をもつ熱電材料を使用しているため、従来の熱電モジュールに比べて、効率的に熱電特性を向上させることができる。 In the present invention, when A is at least one element selected from the group consisting of Bi and Sb, a composition represented by A 2 Te x Se 3-x and a part of Te at the 6c site is Since a thermoelectric material having a crystal structure substituted with Se is used, thermoelectric characteristics can be improved more efficiently than conventional thermoelectric modules.

本発明によれば、ＡをＢｉ及びＳｂからなる群から選択された少なくとも１種の元素としたとき、Ａ２ＴｅｘＳｅ３−ｘで表される組成の熱電材料において、６ｃサイトのＴｅの一部がＳｅで置換された結晶構造となっているため、結晶構造が歪み、フォノン散乱効果により、比抵抗ρを増加させずに熱伝導率κを低くすることができる。 According to the present invention, when A is at least one element selected from the group consisting of Bi and Sb, in a thermoelectric material having a composition represented by A 2 Te x Se 3-x , Since the crystal structure is partially substituted with Se, the crystal structure is distorted, and the thermal conductivity κ can be lowered without increasing the specific resistance ρ due to the phonon scattering effect.

以下、本発明の実施の形態について、添付の図面を参照して具体的に説明する。先ず、本発明の第１の実施形態に係る熱電材料について説明する。本実施形態の熱電材料は、ＡをＢｉ及びＳｂからなる群から選択された少なくとも１種の元素としたとき、Ａ２ＴｅｘＳｅ３−ｘで表される組成の六方晶系熱電材料であり、３ａサイトのＴｅの一部及び６ｃサイトのＴｅの一部がＳｅで置換され、３ａサイト及び６ｃサイトの両方にＳｅが配置された結晶構造となっている。 Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. First, the thermoelectric material according to the first embodiment of the present invention will be described. The thermoelectric material of this embodiment is a hexagonal thermoelectric material having a composition represented by A 2 Te x Se 3-x when A is at least one element selected from the group consisting of Bi and Sb. A part of Te at the 3a site and a part of Te at the 6c site are substituted with Se, and a crystal structure is formed in which Se is arranged at both the 3a site and the 6c site.

以下、本実施形態の熱電材料について、Ｂｉ２ＴｅｘＳｅ３−ｘを例にして詳細に説明する。図１は本実施形態の熱電材料の結晶構造の一例を示す図であり、図２はＢｉ２Ｔｅ３の結晶構造を示す図である。図２に示すように、Ｂｉ２Ｔｅ３の結晶構造は空間群

Figure 0004479628
で示され、その結晶構造中には、１種類のＢｉと、位置するサイトが相互に異なる２種類のＴｅ（Ｔｅ１，Ｔｅ２）が存在する。具体的には、単位格子内に、６ｃサイトに位置するＢｉ、６ｃサイトに位置するＴｅ１及び３ａサイトに位置するＴｅ２の１５個の元素が配置されており、結晶学的にはＢｉ２Ｔｅ１２Ｔｅ２と表される。 Hereinafter, the thermoelectric material of the present embodiment will be described in detail using Bi 2 Te x Se 3-x as an example. FIG. 1 is a diagram showing an example of the crystal structure of the thermoelectric material of the present embodiment, and FIG. 2 is a diagram showing the crystal structure of Bi 2 Te 3 . As shown in FIG. 2, the crystal structure of Bi 2 Te 3 is a space group.
Figure 0004479628
In the crystal structure, there are one kind of Bi and two kinds of Te (Te1, Te2) whose sites are different from each other. Specifically, 15 elements of Bi located at the 6c site, Te1 located at the 6c site, and Te2 located at the 3a site are arranged in the unit cell, and Bi 2 Te1 2 is crystallographically. Represented as Te2.

また、一般に、Ｂｉ２Ｔｅ３を熱電材料として使用する場合、熱電特性を調整するためにＳｅが添加され、例えば、Ｂｉ２Ｔｅ２．７Ｓｅ０．３に代表される組成に調整される。そして、Ｂｉ２Ｔｅ２．７Ｓｅ０．３等の様にＳｅが添加された従来のＢｉ２Ｔｅ３系熱電材料は、３ａサイトに位置するＴｅ２がＳｅに置換された結晶構造となっている。図３はＢｉ２Ｔｅ２Ｓｅの結晶構造を示す図であり、図４は横軸にＴｅ量をとり、縦軸に熱伝導率κのうち格子振動（フォノン）による成分κｐｈをとって、Ｓｅ置換量と格子熱伝導率κｐｈとの関係を示すグラフ図である。図４に示すように、３ａサイトに位置するＴｅ２が全てＳｅで置換されたＢｉ２Ｔｅ２Ｓｅ（図３）及びＳｅが添加されていないＢｉ２Ｔｅ３（図２）は、いずれも結晶構造が安定しているため格子熱伝導率κｐｈが高い。これに対して、３ａサイトに位置するＴｅ２の一部がＳｅで置換されたものは、結晶構造が歪み、図２及び図３に示す結晶構造のものに比べて、格子熱伝導率κｐｈが低下する。 In general, when Bi 2 Te 3 is used as a thermoelectric material, Se is added to adjust the thermoelectric characteristics, and for example, the composition is typified by Bi 2 Te 2.7 Se 0.3 . The conventional Bi 2 Te 3 -based thermoelectric material Se is added as such Bi 2 Te 2.7 Se 0.3 is, Te2 located 3a site is a crystal structure substituted in Se . FIG. 3 is a diagram showing the crystal structure of Bi 2 Te 2 Se, FIG. 4 shows the amount of Te on the horizontal axis, and the component κ ph due to lattice vibration (phonon) of the thermal conductivity κ on the vertical axis, It is a graph which shows the relationship between Se substitution amount and lattice thermal conductivity (kappa) ph . As shown in FIG. 4, Bi 2 Te 2 Se (FIG. 3) in which all Te2 located at the 3a site are replaced with Se and Bi 2 Te 3 (FIG. 2) to which Se is not added are both crystal structures. Is stable, the lattice thermal conductivity κph is high. On the other hand, when Te2 located at the 3a site is partially substituted with Se, the crystal structure is distorted, and the lattice thermal conductivity κ ph is higher than that of the crystal structure shown in FIGS. descend.

更に、図１に示す本実施形態の熱電材料のように、３ａサイトに位置するＴｅ２の一部だけでなく、６ｃサイトに位置するＴｅ１の一部もＳｅに置換されていると、結晶構造の歪みが増し、Ｔｅ２がＳｅに置換された従来の熱電材料に比べて格子熱伝導率κｐｈを大幅に低減することができる。 Further, as in the thermoelectric material of the present embodiment shown in FIG. 1, when not only a part of Te2 located at the 3a site but also a part of Te1 located at the 6c site is replaced with Se, the crystalline structure The strain thermal conductivity κ ph can be greatly reduced as compared with the conventional thermoelectric material in which the strain is increased and Te2 is replaced with Se.

ここで、全Ｓｅ量に対する６ｃサイトに置換されているＳｅの量の割合（＝６ｃサイトに位置するＳｅ量／全Ｓｅ量）を占有率として定義する。例えば、Ｂｉ２Ｔｅ３のＴｅをＳｅで１０原子％置換した場合（Ｂｉ２Ｔｅ２．７Ｓｅ０．３）、従来の熱電材料では、Ｓｅは全て３ａサイトに配置されるため、Ｂｉ２Ｔｅ１２（Ｔｅ２０．７Ｓｅ０．３）となり、６ｃサイトにおけるＳｅの占有率は０％となる。一方、本実施形態の熱電材料のように、Ｓｅが６ｃサイトにも配置される場合、Ｂｉ２（Ｔｅ１１．７Ｓｅ０．３）Ｔｅ２となり、この場合、６ｃサイトにおけるＳｅの占有率は１００％となる。この６ｃサイトにおけるＳｅの占有率（＝６ｃサイトに位置するＳｅ量／全Ｓｅ量）は、３０原子％以上であることが好ましい。これにより、Ｓｅの置換率が同じである従来の熱電材料に比べて、熱導電率κを１５％以上低減することができると共に、性能指数Ｚを３．０以上にすることができる。一方、６ｃサイトにおけるＳｅの占有率が３０原子％未満であると、熱導電率の低減率が５％以上１５％未満となる。 Here, the ratio of the amount of Se substituted for the 6c site to the total Se amount (= Se amount located at the 6c site / total Se amount) is defined as the occupation ratio. For example, when Te of Bi 2 Te 3 is replaced with Se at 10 atomic% (Bi 2 Te 2.7 Se 0.3 ), in the conventional thermoelectric material, all Se is arranged at the 3a site, so Bi 2 Te1 2 (Te2 0.7 Se 0.3 ), and the Se occupation ratio at the 6c site is 0%. On the other hand, when Se is also arranged at the 6c site as in the thermoelectric material of the present embodiment, Bi 2 (Te1 1.7 Se 0.3 ) Te2 is obtained. In this case, the occupation ratio of Se at the 6c site is 100. %. It is preferable that the Se occupancy in the 6c site (= Se amount located in the 6c site / total Se amount) is 30 atomic% or more. Thereby, compared with the conventional thermoelectric material with the same substitution rate of Se, thermal conductivity (kappa) can be reduced 15% or more, and the figure of merit Z can be set to 3.0 or more. On the other hand, when the Se occupancy rate at the 6c site is less than 30 atomic%, the reduction rate of the thermal conductivity is 5% or more and less than 15%.

本実施形態の熱電材料のように、３ａサイトだけでなく、６ｃサイトにもＳｅが配置されていると、結晶構造が歪み、比抵抗ρを増加させずに、熱伝導率κを低減することができる。その結果、性能指数Ｚを効率的に向上させることができる。   When Se is disposed not only at the 3a site but also at the 6c site as in the thermoelectric material of the present embodiment, the crystal structure is distorted and the thermal conductivity κ is reduced without increasing the specific resistance ρ. Can do. As a result, the figure of merit Z can be improved efficiently.

なお、本実施形態においては、Ａ２ＴｅｘＳｅ３−ｘで表される組成の熱電材料のうち、ＡがＢｉである場合を例にして説明しているが、本発明はこれに限定されるものではなく、６ｃサイトのＴｅの一部がＳｅで置換された結晶構造の六方晶系熱電材料であればよく、ＡはＢｉ及びＳｂからなる群から選択された少なくとも１種の元素とすることができる。そして、組成がＳｂ２ＴｅｘＳｅ３−ｘである場合は、図１に示すＢｉ２ＴｅｘＳｅ３−ｘのＢｉが全てＳｂで置換された結晶構造となり、また、組成がＢｉｙＳｂ２−ｙＴｅｘＳｅ３−ｘである場合は、図１に示すＢｉ２ＴｅｘＳｅ３−ｘのＢｉの一部がＳｂで置換された結晶構造となる。 In the present embodiment, among the thermoelectric materials having a composition represented by A 2 Te x Se 3-x , the case where A is Bi is described as an example. However, the present invention is not limited to this. Instead, any hexagonal thermoelectric material having a crystal structure in which a part of Te at the 6c site is substituted with Se may be used, and A is at least one element selected from the group consisting of Bi and Sb. be able to. When the composition is Sb 2 Te x Se 3-x , the Bi 2 Te x Se 3-x Bi shown in FIG. 1 has a crystal structure in which all Bi is substituted with Sb, and the composition is Bi y Sb 2. If a -y Te x Se 3-x is a crystalline structure which is partially substituted by Sb and Bi in Bi 2 Te x Se 3-x shown in FIG.

また、本実施形態の熱電材料の結晶構造におけるＴｅ及びＳｅの配置は、Ｘ線チャンネリング分光法及び粉末Ｘ線回折図形を使用したＲｉｅｔｖｅｌｄ解析により精度よく評価することができる。   In addition, the arrangement of Te and Se in the crystal structure of the thermoelectric material of the present embodiment can be accurately evaluated by Rietveld analysis using X-ray channeling spectroscopy and powder X-ray diffraction patterns.

次に、本発明の第２の実施形態として、前述の第１の実施形態の熱電材料の製造方法について説明する。図５は本実施形態の熱電材料の製造方法を示すフローチャート図である。図５に示すように、本実施形態の熱電材料の製造方法においては、先ず、Ｂｉ及びＳｂからなる群から選択された少なくとも１種の元素、Ｔｅ及びＳｅが所望の組成となるように原料を秤量する（ステップＳ１）。   Next, as a second embodiment of the present invention, a method for manufacturing the thermoelectric material of the first embodiment will be described. FIG. 5 is a flowchart showing the method for manufacturing the thermoelectric material of the present embodiment. As shown in FIG. 5, in the method for manufacturing a thermoelectric material of this embodiment, first, the raw materials are used so that at least one element selected from the group consisting of Bi and Sb, Te and Se, has a desired composition. Weigh (step S1).

次に、秤量した原料粉を石英製のアンプルに入れた後、アンプル内を真空引きし、その内部を真空状態又は不活性ガスを導入した状態として、アンプルの口を封じ切る（ステップＳ２）。そして、このアンプルをスタンドに回転可能な状態で支持された管状炉内に入れ、６００乃至７００℃に加熱することにより原料粉を溶解し、更に、管状炉を揺動させながら原料融液を撹拌する（ステップＳ３）。その後、融液を冷却して凝固させてインゴットとする（ステップＳ４）。次に、液体急冷法により、冷却速度を１×１０３Ｋ／秒以上にして急冷凝固させて、ステップＳ４で作製したインゴットを、箔片状及び／又は粉末状にする（ステップＳ５）。このとき、冷却速度が１×１０３Ｋ／秒未満であると、６ｃサイトのＴｅがＳｅで置換されない。本実施形態の熱電材料の製造方法において適用可能な液体急冷法としては、例えば単ロール法、双ロール法、ガスアトマイズ法及び回転ディスク法等が挙げられる。これにより、Ａ２ＴｅｘＳｅ３−ｘで表される組成で、６ｃサイトのＴｅの一部がＳｅで置換された結晶構造をもつ六方晶系の熱電材料の箔片及び／又は粉末が得られる。 Next, after putting the weighed raw material powder into a quartz ampule, the inside of the ampule is evacuated, and the inside of the ampule is sealed with the vacuum state or an inert gas introduced therein (step S2). The ampoule is placed in a tubular furnace supported by a stand so as to be rotatable, heated to 600 to 700 ° C. to dissolve the raw material powder, and the raw material melt is stirred while the tubular furnace is swung. (Step S3). Thereafter, the melt is cooled and solidified to form an ingot (step S4). Next, the ingot produced in step S4 is made into a foil piece and / or a powder form by rapidly cooling and solidifying by a liquid quenching method at a cooling rate of 1 × 10 3 K / second or more (step S5). At this time, if the cooling rate is less than 1 × 10 3 K / sec, Te at the 6c site is not replaced with Se. Examples of the liquid quenching method applicable in the method for producing a thermoelectric material of the present embodiment include a single roll method, a twin roll method, a gas atomizing method, and a rotating disk method. As a result, a foil piece and / or a powder of a hexagonal thermoelectric material having a composition represented by A 2 Te x Se 3-x and having a crystal structure in which a part of Te at the 6c site is substituted with Se is obtained. It is done.

次に、得られた箔片及び／又は粉末を、マイクロ波焼結法又は通電加熱焼結法により固化成形する（ステップＳ６）。図６は図１に示す熱電材料のＳｅが再配列した場合の結晶構造を示す図である。Ｂｉ２Ｔｅ３系化合物及びＳｂ２Ｔｅ３系化合物においては、Ｓｅ等の添加元素は３ａサイトに入りやすく、長時間加熱したり、水素還元したりすると、図６に示すように、６ｃサイトに位置していたＳｅが３ａサイトに再配列されてしまう。その結果、結晶構造が安定になり、格子熱導電率κｐｈを低減する効果が得られなくなる。このため、本実施形態の熱電材料の製造方法においては、固化成形時の加熱時間を極短時間にしている。 Next, the obtained foil piece and / or powder is solidified by a microwave sintering method or an electric heating sintering method (step S6). FIG. 6 is a view showing a crystal structure when Se of the thermoelectric material shown in FIG. 1 is rearranged. In the Bi 2 Te 3 series compound and the Sb 2 Te 3 series compound, an additive element such as Se easily enters the 3a site, and when heated for a long time or reduced with hydrogen, as shown in FIG. The located Se is rearranged to the 3a site. As a result, the crystal structure becomes stable and the effect of reducing the lattice thermal conductivity κph cannot be obtained. For this reason, in the manufacturing method of the thermoelectric material of this embodiment, the heating time at the time of solidification molding is made extremely short.

具体的には、マイクロ波焼結法により固化成形する場合は、ステップＳ５により得られた箔片及び／又は粉末を、冷間プレスによりペレット化した後、周波数を例えば１乃至３０ＧＨｚとし、焼結時間ｔ（分）及び焼結温度Ｔ（℃）が下記数式３に表される範囲内になるようにする。また、図７は横軸に焼結時間をとり、縦軸に焼結温度をとって、固化成形条件と性能指数Ｚとの関係を示すグラフ図である。焼結温度Ｔが（−２５×ｔ＋５７５）℃未満となるような条件で固化成形すると、成形体の密度が９５％以上にならず、比抵抗ρが増加してしまう。また、焼結温度Ｔが（−１２．５×ｔ＋５７５）℃以上となるような条件で固化成形すると、６ｃサイトに位置していたＳｅが全て３ａサイトに再配列してしまう。これに対して、図７に示すように、下記数式３に示す条件、即ち、焼結温度Ｔが（−２５×ｔ＋５７５）℃以上で且つ（−１２．５×ｔ＋５７５）℃未満となるようにすると、性能指数Ｚを２．５以上にすることができる。   Specifically, when solidifying and molding by the microwave sintering method, the foil piece and / or powder obtained in step S5 is pelletized by cold pressing, and then the frequency is set to 1 to 30 GHz, for example. The time t (minutes) and the sintering temperature T (° C.) are set within the range represented by the following mathematical formula 3. FIG. 7 is a graph showing the relationship between the solidification molding conditions and the figure of merit Z with the sintering time on the horizontal axis and the sintering temperature on the vertical axis. If solidification molding is performed under such a condition that the sintering temperature T is less than (−25 × t + 575) ° C., the density of the molded body does not reach 95% or more, and the specific resistance ρ increases. Further, if solidification molding is performed under such a condition that the sintering temperature T is (−12.5 × t + 575) ° C. or higher, all the Se located at the 6c site is rearranged at the 3a site. On the other hand, as shown in FIG. 7, the condition shown in the following mathematical formula 3, that is, the sintering temperature T is (−25 × t + 575) ° C. or more and less than (−12.5 × t + 575) ° C. Then, the figure of merit Z can be 2.5 or more.

Figure 0004479628
Figure 0004479628

なお、マイクロ波焼結法での固化成形条件は、下記数式４に示す範囲内、即ち、焼結温度Ｔが（−２５×ｔ＋５７５）℃以上で且つ（−１８．８×ｔ＋５７８．１）℃未満であることが好ましい。これにより、６ｃサイトにおけるＳｅ占有率を３０原子％以上にすることができるため、Ｓｅの置換率が同じである従来の熱電材料に比べて、格子熱伝導率κｐｈを１５％以上低減することができると共に、性能指数Ｚを３．０以上にすることができる。 The solidification molding conditions in the microwave sintering method are within the range shown in the following formula 4, that is, the sintering temperature T is (−25 × t + 575) ° C. or higher and (−18.8 × t + 578.1) ° C. It is preferable that it is less than. As a result, the Se occupancy at the 6c site can be increased to 30 atomic% or more, and therefore, the lattice thermal conductivity κ ph is reduced by 15% or more compared to conventional thermoelectric materials having the same Se substitution rate. And the figure of merit Z can be 3.0 or more.

Figure 0004479628
Figure 0004479628

同様に、通電加熱焼結法により固化成形する場合は、ステップＳ５により得られた箔片及び／又は粉末を、金型に充填した後、例えば２０乃至５００ＭＰａの圧力を印加しながら通電し、１００乃至５００℃／分の速度で昇温して、焼結時間ｔ（分）及び焼結温度Ｔ（℃）が上記数式３に表される範囲内になるようにする。このとき、焼結温度Ｔが（−２５×ｔ＋５７５）℃未満となるような条件で固化成形すると、成形体の密度が９５％以上にならず、比抵抗ρが増加してしまう。一方、加熱温度Ｔが（−１２．５×ｔ＋５７５）℃以上となるような条件で固化成形すると、６ｃサイトに位置していたＳｅが全て３ａサイトに再配列してしまう。よって、通電加熱焼結法により固化成形する場合は、上記数式３に示す条件、即ち、焼結温度Ｔが（−２５×ｔ＋５７５）℃以上で且つ（−１２．５×ｔ＋５７５）℃未満となるようにする。なお、通電加熱焼結法での固化成形条件は、上記数式４に示す範囲内、即ち、加熱温度Ｔが（−２５×ｔ＋５７５）℃以上で且つ（−１８．８×ｔ＋５７８．１）℃未満であることが好ましい。これにより、６ｃサイトにおけるＳｅ占有率を３０原子％以上にすることができるため、Ｓｅの置換率が同じである従来の熱電材料に比べて、格子熱伝導率κｐｈを１５％以上低減することができると共に、性能指数Ｚを３．０以上にすることができる。 Similarly, in the case of solidification molding by the electric heating and sintering method, after filling the mold with the foil pieces and / or powder obtained in step S5, the electric current is applied while applying a pressure of 20 to 500 MPa, for example. The temperature is raised at a rate of 500 ° C./min so that the sintering time t (min) and the sintering temperature T (° C.) are within the range represented by the above Equation 3. At this time, if solidification molding is performed under such a condition that the sintering temperature T is less than (−25 × t + 575) ° C., the density of the compact does not reach 95% or more, and the specific resistance ρ increases. On the other hand, if solidification molding is performed under such a condition that the heating temperature T is (−12.5 × t + 575) ° C. or higher, all the Se located at the 6c site is rearranged at the 3a site. Therefore, in the case of solidification molding by the electric heating and sintering method, the condition shown in Equation 3 above, that is, the sintering temperature T is (−25 × t + 575) ° C. or more and less than (−12.5 × t + 575) ° C. Like that. It should be noted that the solidification molding conditions in the electric heating sintering method are within the range shown in Formula 4 above, that is, the heating temperature T is (−25 × t + 575) ° C. or higher and less than (−18.8 × t + 578.1) ° C. It is preferable that As a result, the Se occupancy at the 6c site can be increased to 30 atomic% or more, and therefore, the lattice thermal conductivity κ ph is reduced by 15% or more compared to conventional thermoelectric materials having the same Se substitution rate. And the figure of merit Z can be 3.0 or more.

更に、前述のマイクロ波焼結法及び通電加熱焼結法以外に、放電プラズマ焼結法により固化成形することもできる。その場合、ステップＳ５により得られた箔片及び／又は粉末を型に入れ、２００乃至５００ＭＰａ程度の圧力を印加しながら、プラズマ発生器等によって箔片及び／又は粉末間で放電プラズマを発生させて、２００乃至６００℃程度の温度条件下で１５分間以内加熱する。その際、焼結時間が１５分間を超えると、６ｃサイトに位置していたＳｅが全て３ａサイトに再配列してしまう。なお、放電プラズマ焼結法により固化成形する際は、焼結温度を４６０℃以下とし、焼結時間を５分間以内とすることが好ましい。これにより、６ｃサイトにおけるＳｅ占有率を３０原子％以上にすることができるため、Ｓｅの置換率が同じである従来の熱電材料に比べて、格子熱導電率κｐｈを１５％以上低減することができると共に、性能指数Ｚを３．０以上にすることができる。 Further, in addition to the above-described microwave sintering method and current heating sintering method, solidification molding can also be performed by a discharge plasma sintering method. In that case, the foil piece and / or powder obtained in step S5 is put into a mold, and a discharge plasma is generated between the foil piece and / or powder by a plasma generator or the like while applying a pressure of about 200 to 500 MPa. And heating within about 15 minutes under a temperature of about 200 to 600 ° C. At that time, if the sintering time exceeds 15 minutes, all the Se located at the 6c site is rearranged at the 3a site. In addition, when solidifying and forming by the discharge plasma sintering method, it is preferable that the sintering temperature is 460 ° C. or less and the sintering time is within 5 minutes. As a result, the Se occupancy at the 6c site can be increased to 30 atomic% or more, so that the lattice thermal conductivity κ ph is reduced by 15% or more compared to the conventional thermoelectric material having the same Se substitution rate. And the figure of merit Z can be 3.0 or more.

本実施形態の熱電材料の製造方法においては、Ｂｉ及びＳｂからなる群から選択された少なくとも１種の元素と、Ｔｅ、Ｓｅ及びＳからなる群から選択された２種以上の元素とを含む組成の原料を、液体急冷法により、冷却速度を１×１０３Ｋ／秒以上にして急冷凝固させて得た箔片及び／又は粉末を、短時間の加熱で固化成形しているため、６ｃサイトのＴｅの一部がＳｅで置換され、６ｃサイトにもＳｅが位置する結晶構造をもつ六方晶系の熱電材料が得られる。これにより、結晶構造を歪ませることができるため、熱電材料の比抵抗ρを増加させずに熱伝導率κを低くすることができる。 In the manufacturing method of the thermoelectric material of the present embodiment, the composition includes at least one element selected from the group consisting of Bi and Sb and two or more elements selected from the group consisting of Te, Se, and S. The foil piece and / or the powder obtained by rapidly solidifying the raw material of the above by rapidly cooling and solidifying the raw material at a cooling rate of 1 × 10 3 K / second or more by the liquid quenching method is solidified and formed by heating in a short time. A part of Te is replaced with Se, and a hexagonal thermoelectric material having a crystal structure in which Se is also located at the 6c site is obtained. Thereby, since the crystal structure can be distorted, the thermal conductivity κ can be lowered without increasing the specific resistance ρ of the thermoelectric material.

なお、本実施形態の熱電材料の製造方法においては、液体急冷法により作製した箔片及び／又は粉末を、マイクロ波焼結法、通電加熱焼結法及び放電プラズマ焼結法等により固化成形しているが、本発明はこれに限定されるものではなく、液体急冷法により作製した箔片を固化成形せずに、そのままモジュール化してもよい。また、液体急冷法以外に、熱電材料のインゴットをアーク溶解した後急冷しても、６ｃサイトのＴｅの一部がＳｅで置換された結晶構造をもつ六方晶系の熱電材料が得られる。   In the method for producing the thermoelectric material of the present embodiment, the foil pieces and / or powders produced by the liquid quenching method are solidified and formed by a microwave sintering method, an electric heating sintering method, a discharge plasma sintering method, or the like. However, the present invention is not limited to this, and the foil piece produced by the liquid quenching method may be modularized as it is without being solidified. In addition to the liquid quenching method, a hexagonal thermoelectric material having a crystal structure in which a part of Te at the 6c site is replaced with Se can be obtained by arc-melting an ingot of a thermoelectric material.

次に、本発明の第３の実施形態に係る熱電モジュールについて説明する。本実施形態の熱電モジュールは、前述の第１の実施形態の熱電材料かならなる複数の熱電素子を、セラミックス等の絶縁材料からなり表面に電極が形成された基板上に搭載したものである。本実施形態の熱電モジュールに搭載される熱電素子としては、例えば前述の第２の実施形態の方法で固化成形された熱電材料から切り出されたもの、及び前述の条件で液体急冷法により急冷凝固して得た熱電材料箔片を所定の大きさに切断したもの等を使用することができる。   Next, a thermoelectric module according to the third embodiment of the present invention will be described. The thermoelectric module of the present embodiment is obtained by mounting a plurality of thermoelectric elements made of the thermoelectric material of the first embodiment on a substrate made of an insulating material such as ceramics and having electrodes formed on the surface. As the thermoelectric element mounted on the thermoelectric module of this embodiment, for example, a thermoelectric material cut out from the thermoelectric material solidified and molded by the method of the second embodiment described above, and rapidly solidified by the liquid quenching method under the aforementioned conditions. A thermoelectric material foil piece obtained by cutting into pieces of a predetermined size can be used.

本実施形態の熱電モジュールにおいては、ＡをＢｉ及びＳｂからなる群から選択された少なくとも１種の元素としたとき、Ａ２ＴｅｘＳｅ３−ｘで表される組成で、且つ６ｃサイトのＴｅの一部がＳｅで置換された結晶構造をもつ熱電材料を使用しているため、比抵抗ρ及び熱伝導率κが共に低く、熱電特性が優れた熱電モジュールが得られる。 In the thermoelectric module of the present embodiment, when A is at least one element selected from the group consisting of Bi and Sb, the composition is represented by A 2 Te x Se 3-x , and Te at 6c site. Since a thermoelectric material having a crystal structure in which a part of is substituted with Se is used, a thermoelectric module having both low specific resistance ρ and thermal conductivity κ and excellent thermoelectric characteristics can be obtained.

以下、本発明の実施例の効果について、本発明の範囲から外れる比較例と比較して説明する。先ず、本発明の第１実施例として、前述の第２の実施形態の熱電材料の製造方法と同様の方法で、組成がＢｉ２Ｔｅ２．７Ｓｅ０．３であるインゴットを作製し、液体急冷法により箔片化し、６ｃサイトにおけるＳｅ占有率が５８％である液体急冷箔片を作製した。そして、この箔片を、直径が３０ｍｍの金型に充填し、冷間で９８ＭＰａの圧力を印加しながらプレスしてペレット化した。このペレットをマイクロ波焼成装置のチャンバー内に配置し、チャンバー内を１．３３Ｐａ（１×１０−２Ｔｏｒｒ）以上の高真空に排気した後、Ａｒガスで置換した。その後、マイクロ波焼結法により、周波数を２８ＧＨｚ、出力を２ｋＷとし、４５０℃で５分間加熱して固化成形し、実施例１の熱電材料を作製した。また、マイクロ波焼結法により、周波数を２ＧＨｚ、出力を５ｋＷとし、５００℃で４分間加熱して固化成形し、実施例２の熱電材料を作製した。更に、マイクロ波焼結法により、周波数を２８ＧＨｚ、出力を２ｋＷとし、３５０℃で１２分間加熱して固化成形し、実施例３の熱電材料を作製した。 Hereinafter, the effect of the Example of this invention is demonstrated compared with the comparative example which remove | deviates from the scope of the present invention. First, as a first example of the present invention, an ingot having a composition of Bi 2 Te 2.7 Se 0.3 is manufactured by the same method as the method for manufacturing the thermoelectric material of the second embodiment, and a liquid is prepared. A foil piece was obtained by a quenching method, and a liquid quenching foil piece having an Se occupation ratio of 58% at the 6c site was produced. And this foil piece was filled in the metal mold | die with a diameter of 30 mm, and it pressed and pelletized, applying the pressure of 98 Mpa in cold. This pellet was placed in a chamber of a microwave baking apparatus, and the inside of the chamber was evacuated to a high vacuum of 1.33 Pa (1 × 10 −2 Torr) or more, and then replaced with Ar gas. Then, the thermoelectric material of Example 1 was produced by microwave sintering method with a frequency of 28 GHz and an output of 2 kW, and heating and solidifying at 450 ° C. for 5 minutes. Moreover, the thermoelectric material of Example 2 was produced by microwave sintering method with a frequency of 2 GHz, an output of 5 kW, and heating at 500 ° C. for 4 minutes for solidification molding. Further, the thermoelectric material of Example 3 was produced by microwave sintering, with a frequency of 28 GHz, an output of 2 kW, and solidified by heating at 350 ° C. for 12 minutes.

次に、液体急冷法により作製した箔片を、直径が３０ｍｍでアルミナ製の型に充填して通電加熱装置のチャンバー内に配置し、チャンバー内を１．３３Ｐａ（１×１０−２Ｔｏｒｒ）以上の高真空に排気した後、Ａｒガスで置換した。そして、通電加熱焼結法により、ＳＫＤ６１鋼製の導電性パンチを使用し、９８ＭＰａの圧力を印加しながら、４８０℃の温度下で４分間加熱して固化成形し、実施例４の熱電材料を作製した。また、通電加熱焼結法により、９８ＭＰａの圧力を印加しながら、５００℃の温度下で５分間加熱して固化成形し、実施例５の熱電材料を作製した。更に、通電加熱焼結法により、９８ＭＰａの圧力を印加しながら、３５０℃の温度下で１５分間加熱して固化成形し、実施例６の熱電材料を作製した。更にまた、通電加熱焼結法により、９８ＭＰａの圧力を印加しながら、４５０℃の温度下で８分間加熱して固化成形し、実施例７の熱電材料を作製した。 Next, the foil piece produced by the liquid quenching method is filled in an alumina mold having a diameter of 30 mm and placed in a chamber of an electric heating device, and the inside of the chamber is 1.33 Pa (1 × 10 −2 Torr) or more. After evacuating to a high vacuum, Ar gas was substituted. Then, by using a conductive punch made of SKD61 steel and applying a pressure of 98 MPa, it was heated and solidified at a temperature of 480 ° C. for 4 minutes, and the thermoelectric material of Example 4 was obtained. Produced. In addition, the thermoelectric material of Example 5 was produced by heating and solidifying at 500 ° C. for 5 minutes while applying a pressure of 98 MPa by an electric heating and sintering method. Furthermore, the thermoelectric material of Example 6 was produced by heating and solidifying by heating at a temperature of 350 ° C. for 15 minutes while applying a pressure of 98 MPa by an electric heating and sintering method. Furthermore, the thermoelectric material of Example 7 was produced by heating and solidifying at 450 ° C. for 8 minutes while applying a pressure of 98 MPa by an electric heating and sintering method.

次に、液体急冷法により作製した箔片を、直径が３０ｍｍの金型に充填して放電プラズマ焼結機のチャンバー内に配置し、チャンバー内を１．３３Ｐａ（１×１０−２Ｔｏｒｒ）以上の高真空に排気した後、Ａｒガスで置換した。そして、放電プラズマ焼結法により、９８ＭＰａの圧力を印加しながら、４６０℃の温度下で５分間加熱して固化成形し、実施例８の熱電材料を作製した。また、放電プラズマ焼結法により、９８ＭＰａの圧力を印加しながら、５００℃の温度下で５分間加熱して固化成形し、実施例９の熱電材料を作製した。また、放電プラズマ焼結法により、９８ＭＰａの圧力を印加しながら、４６０℃の温度下で１５分間加熱して固化成形し、実施例１０の熱電材料を作製した。 Next, the foil piece produced by the liquid quenching method is filled in a mold having a diameter of 30 mm and placed in a chamber of a discharge plasma sintering machine, and the inside of the chamber is 1.33 Pa (1 × 10 −2 Torr) or more. After evacuating to a high vacuum, Ar gas was substituted. Then, by applying a pressure of 98 MPa by the discharge plasma sintering method, the mixture was heated and solidified at a temperature of 460 ° C. for 5 minutes to produce a thermoelectric material of Example 8. Further, by applying a pressure of 98 MPa by a discharge plasma sintering method, it was heated and solidified at a temperature of 500 ° C. for 5 minutes to produce a thermoelectric material of Example 9. Further, by applying a pressure of 98 MPa by a discharge plasma sintering method, it was heated and solidified at a temperature of 460 ° C. for 15 minutes to produce a thermoelectric material of Example 10.

次に、組成がＢｉ２Ｔｅ２．７Ｓｅ０．３であるインゴットを、アーク溶解装置の水冷るつぼに充填し、チャンバー内を１．３３Ｐａ（１×１０−２Ｔｏｒｒ）以上の高真空に排気した。そして、チャンバー内をＡｒガスで置換し、６５０℃の温度条件下でインゴットをアーク溶解した後、水冷により溶融物全体を、冷却速度１×１０２Ｋ／秒で急冷し、実施例１１の熱電材料を作製した。 Next, an ingot having a composition of Bi 2 Te 2.7 Se 0.3 is filled into a water-cooled crucible of an arc melting apparatus, and the inside of the chamber is evacuated to a high vacuum of 1.33 Pa (1 × 10 −2 Torr) or more. did. Then, the inside of the chamber was replaced with Ar gas, and the ingot was arc-melted under a temperature condition of 650 ° C., and then the entire melt was quenched by water cooling at a cooling rate of 1 × 10 2 K / sec. The material was made.

次に、前述の第２の実施形態の熱電材料の製造方法と同様の方法で、組成がＢｉ０．４Ｓｂ１．６Ｔｅ２．８Ｓｅ０．２であるインゴットを作製し、液体急冷法により箔片化した。なお、この液体急冷箔片の６ｃサイトにおけるＳｅ占有率は６３％であった。そして、この箔片を、直径が３０ｍｍの金型に充填し、冷間で９８ＭＰａの圧力を印加しながらプレスしてペレット化した。このペレットをマイクロ波焼成装置のチャンバー内に配置し、チャンバー内を１．３３Ｐａ（１×１０−２Ｔｏｒｒ）以上の高真空に排気した後、Ａｒガスで置換した。その後、マイクロ波焼結法により、周波数を２８ＧＨｚ、出力を１ｋＷとし、５００℃で３分間加熱して固化成形し、実施例１２の熱電材料を作製した。 Next, an ingot having a composition of Bi 0.4 Sb 1.6 Te 2.8 Se 0.2 is prepared by a method similar to the method for manufacturing the thermoelectric material of the second embodiment described above, and a liquid quenching method is performed. The foil was cut into pieces. In addition, the Se occupation rate in the 6c site of this liquid quenching foil piece was 63%. And this foil piece was filled in the metal mold | die with a diameter of 30 mm, and it pressed and pelletized, applying the pressure of 98 Mpa in cold. This pellet was placed in a chamber of a microwave baking apparatus, and the inside of the chamber was evacuated to a high vacuum of 1.33 Pa (1 × 10 −2 Torr) or more, and then replaced with Ar gas. Then, the thermoelectric material of Example 12 was produced by microwave sintering method with a frequency of 28 GHz, an output of 1 kW, and solidified by heating at 500 ° C. for 3 minutes.

次に、実施例で使用した箔片と同じ箔片を、マイクロ波焼結法により、前述の実施例と同様の方法で、周波数を２ＧＨｚ、出力を５ｋＷとし、４５０℃で１０分間加熱して固化成形し、比較例１の熱電材料を作製した。また、液体急冷法により作製した箔片を、通電加熱焼結法により、９８ＭＰａの圧力を印加しながら、３５０℃の温度下で５分間加熱して固化成形し、比較例２の熱電材料を作製した。更に、通電加熱焼結法により、９８ＭＰａの圧力を印加しながら、３５０℃の温度下で２０分間加熱して固化成形し、比較例５の熱電材料を作製した。   Next, the same foil piece as the foil piece used in the example was heated at 450 ° C. for 10 minutes at a frequency of 2 GHz, an output of 5 kW, by the same method as in the previous example, by the microwave sintering method. The thermoelectric material of Comparative Example 1 was produced by solidification molding. Further, the foil piece produced by the liquid quenching method was solidified by heating at 350 ° C. for 5 minutes while applying a pressure of 98 MPa by the electric heating sintering method, and the thermoelectric material of Comparative Example 2 was produced. did. Furthermore, the thermoelectric material of Comparative Example 5 was produced by heating and solidifying by heating at 350 ° C. for 20 minutes while applying a pressure of 98 MPa by an electric heating and sintering method.

次に、液体急冷法により作製した箔片を、ホットプレス法により、９８ＭＰａの圧力を印加しながら、４６０℃の温度下で５分間加熱して固化成形し、比較例３の熱電材料を作製した。また、ホットプレス法により、９８ＭＰａの圧力を印加しながら、４６０℃の温度下で６０分間加熱して固化成形し、比較例４の熱電材料を作製した。なお、これら実施例１乃至１２及び比較例１乃至５の熱電材料においては、熱伝導率κのうちキャリアによる成分κキャリアの効果を除去するため、比抵抗ρが１．０×１０−５Ω・ｍ程度になるように、キャリア濃度を調整している。 Next, the foil piece produced by the liquid quenching method was solidified by heating at a temperature of 460 ° C. for 5 minutes while applying a pressure of 98 MPa by a hot press method, and a thermoelectric material of Comparative Example 3 was produced. . In addition, the thermoelectric material of Comparative Example 4 was produced by heating and solidifying by heating at a temperature of 460 ° C. for 60 minutes while applying a pressure of 98 MPa by a hot press method. In the thermoelectric materials of Examples 1 to 12 and Comparative Examples 1 to 5, the specific resistance ρ is 1.0 × 10 −5 Ω in order to remove the effect of the component κ carrier due to the carrier in the thermal conductivity κ.・ The carrier concentration is adjusted to be about m.

次に、上述の方法で作製した実施例１、１２、参考例２、３、４、５、６、７、８、９、１０、１１及び比較例１乃至５の熱電材料について、熱電物性及び６ｃサイトにおけるＳｅの占有率を調べた。その結果を下記表１及び表２に示す。なお、下記表１及び表２に示すＳｅの占有率はＸ線チャンネリング分光法により求めた。また、評価は、６ｃサイトにおけるＳｅの占有率が３０原子％以上で且つ性能指数Ｚが３．０よりも大きいものを○、Ｓｅ占有率が０よりも大きく且つ３０原子％未満であり、性能指数Ｚが２．５よりも大きいものを△、Ｓｅ占有率が０原子％又は性能指数Ｚが２．５よりも小さいもの場合を×とした。 Next, the thermoelectric properties and the thermoelectric materials of Examples 1 and 12, Reference Examples 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11 and Comparative Examples 1 to 5 produced by the above-described method Se occupancy at the 6c site was examined. The results are shown in Tables 1 and 2 below. The Se occupancy shown in Tables 1 and 2 below was determined by X-ray channeling spectroscopy. In addition, the evaluation is that the Se occupancy at the 6c site is 30 atomic% or more and the figure of merit Z is larger than 3.0, the Se occupancy is larger than 0 and less than 30 atomic%. A case where the index Z was larger than 2.5 was evaluated as Δ, and a case where the Se occupation ratio was 0 atomic% or the performance index Z was smaller than 2.5 was evaluated as x.

Figure 0004479628
Figure 0004479628

Figure 0004479628
Figure 0004479628

上記表１に示すように、比較例１、２及び５の熱電材料は、作製条件が本発明の範囲を超えているため、６ｃサイトに位置するＳｅが全て３ａサイトに再配列し、６ｃサイトにおけるＳｅ含有率が０％であった。その結果、比較例１、２及び５の熱電材料は、熱伝導率κが高く、性能指数Ｚが低かった。また、ホットプレス法により短時間加熱で固化成形した比較例３の熱電材料は、Ｓｅ占有率は高いが、焼結が不十分であるため密度が低く、比抵抗ρを低減することができなかった。その結果、比抵抗ρが高く、性能指数Ｚが低かった。更に、ホットプレス法により長時間加熱して固化成形した比較例４の熱電材料は、焼結度を向上させることができるため比抵抗ρを低減することはできたが、６ｃサイト位置していたＳｅが全て３ａサイトに再配列し、６ｃサイトにおけるＳｅ含有率が０％であった。その結果、熱伝導率κが高く、性能指数Ｚが低かった。   As shown in Table 1, since the thermoelectric materials of Comparative Examples 1, 2, and 5 have production conditions exceeding the scope of the present invention, all the Se located at the 6c site are rearranged at the 3a site. The Se content in was 0%. As a result, the thermoelectric materials of Comparative Examples 1, 2, and 5 had a high thermal conductivity κ and a low figure of merit Z. In addition, the thermoelectric material of Comparative Example 3 solidified and formed by heating for a short time by a hot press method has a high Se occupancy ratio, but has a low density because of insufficient sintering, and cannot reduce the specific resistance ρ. It was. As a result, the specific resistance ρ was high and the figure of merit Z was low. Furthermore, the thermoelectric material of Comparative Example 4 that was solidified by heating for a long time by the hot press method was able to improve the degree of sintering, so that the specific resistance ρ could be reduced, but it was located at the 6c site. All of the Se rearranged to the 3a site, and the Se content at the 6c site was 0%. As a result, the thermal conductivity κ was high and the figure of merit Z was low.

一方、上記表１及び表２に示すように、実施例１、１２及び参考例２、３、４、５、６、７、８、９、１０、１１の熱電材料は、いずれも６ｃサイトにＳｅが配置されており、６ｃサイトのＴｅの一部がＳｅで置換された結晶構造であった。このため、比抵抗ρを増加させずに、熱伝導率κを低減することができた。その結果、性能指数Ｚが向上し、２．５を超えていた。特に、マイクロ波焼結法により焼結温度を４５０℃、焼結時間を５分間として固化成形した実施例１の熱電材料、通電加熱焼結法により焼結温度を４８０℃、焼結時間を４分間として固化成形した参考例４の熱電材料、放電プラズマ焼結法により焼結温度を４６０℃、焼結時間を５分間として固化成形した参考例８の熱電材料、アーク溶解法により固化成形した参考例１１の熱電材料及びマイクロ波焼結法により焼結温度を５００℃、焼結時間を３分間として固化成形した実施例１２の熱電材料は、６ｃサイトにおけるＳｅ含有率が３０原子％よりも高くなり、性能指数Ｚが３．０を超えていた。 On the other hand, as shown in Table 1 and Table 2 above, the thermoelectric materials of Examples 1 and 12 and Reference Examples 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , and 11 are all on the 6c site. Se was arranged, and a crystal structure in which a part of Te at the 6c site was substituted with Se. For this reason, the thermal conductivity κ could be reduced without increasing the specific resistance ρ. As a result, the figure of merit Z was improved and exceeded 2.5. In particular, the thermoelectric material of Example 1 solidified and formed by a microwave sintering method with a sintering temperature of 450 ° C. and a sintering time of 5 minutes, a sintering temperature of 480 ° C. and a sintering time of 4 by an electric heating sintering method. solidified molded thermoelectric material of reference example 4 as between minute, spark plasma sintering 460 ° C. the sintering temperature by sintering method, the thermoelectric material of reference example 8 was solidified molded sintering time as 5 minutes, the reference solidified molded by arc melting method The thermoelectric material of Example 12, which was solidified and molded by the thermoelectric material of Example 11 and the microwave sintering method at a sintering temperature of 500 ° C. and a sintering time of 3 minutes, had a Se content higher than 30 atomic% at the 6c site. The figure of merit Z was over 3.0.

次に、本発明の第２実施例として、前述の第２の実施形態の熱電材料の製造方法と同様の方法で、組成がＢｉ２Ｔｅ２．７Ｓｅ０．３であるインゴットを作製し、液体急冷法により冷却速度を１×１０３Ｋ／秒以上にして箔片化し、実施例２１の液体急冷箔片を作製した。また、実施例２１と同じインゴットを使用し、液体急冷法により冷却速度を１×１０３Ｋ／秒未満にして、箔片化し、比較例２２の液体急冷箔片を作製した。更に、実施例２１の液体急冷箔片を、水素雰囲気中で、４００℃の温度条件下で、１０時間脱酸素処理を施して、比較例２３の液体急冷箔片を作製した。そして、前述の第１実施例と同様の方法で、これらの液体急冷箔片の６ｃサイトにおけるＳｅ占有率を測定したところ、実施例２１は５８％であったが、冷却速度が１×１０３Ｋ／秒未満であった比較例２２は、２８％であり、水素還元処理を施した比較例２３は１８％であった。 Next, as a second example of the present invention, an ingot having a composition of Bi 2 Te 2.7 Se 0.3 is manufactured by the same method as the method of manufacturing the thermoelectric material of the second embodiment described above, A liquid quenching method was performed to make a foil piece by setting the cooling rate to 1 × 10 3 K / second or more by a liquid quenching method. Moreover, the same ingot as Example 21 was used, the cooling rate was made into less than 1 * 10 < 3 > K / sec by the liquid quenching method, it was made into foil pieces, and the liquid quenching foil piece of the comparative example 22 was produced. Further, the liquid quenched foil piece of Example 21 was deoxygenated for 10 hours under a temperature condition of 400 ° C. in a hydrogen atmosphere to prepare a liquid quenched foil piece of Comparative Example 23. And when the Se occupation rate in 6c site of these liquid quenching foil pieces was measured by the method similar to the above-mentioned 1st Example, Example 21 was 58%, but the cooling rate was 1 * 10 <3>. The comparative example 22 which was less than K / sec was 28%, and the comparative example 23 which performed the hydrogen reduction process was 18%.

次に、本発明の第３実施例として、液体急冷法により作製した箔片をモジュール化し、その特性を評価した。具体的には、前述の第２の実施形態の熱電材料の製造方法と同様の方法で、組成がＢｉ２Ｔｅ２．７Ｓｅ０．３であるインゴットを作製し、液体急冷法により冷却速度を１×１０３Ｋ／秒以上にして箔片化してｎ型熱電材料箔片を作製した。また、同様の方法で、組成がＢｉ０．４Ｓｂ１．６Ｔｅ２．９Ｓｅ０．１であるｐ型熱電材料箔片を作製した。これらｎ型及びｐ型熱電材料箔片の厚さは、共に１０μｍであった。次に、このｎ型及びｐ型熱電材料箔片を、ダイシング切断機により、縦１００μｍ、横１００μｍに切断した。そして、この切断された熱電材料箔片を、厚さが０．１ｍｍのアルミナ基板上に形成され、表面にはんだが塗布されている電極上に実装した。更に、このアルミナ基板上に実装されたｎ型及びｐ型熱電材料箔片上に、表面にはんだが塗布されている電極が形成された厚さが０．１ｍｍのアルミナ基板を、はんだ面が熱電材料箔片側になるように配置した後、加熱プレスし、はんだを介してｎ型及びｐ型熱電材料箔片と電極とを接合し、実施例３１の熱電モジュールを作製した。なお、この熱電モジュールにおける横断面サイズ（基板サイズ）は、縦２．６ｍｍ、横２．６ｍｍであった。 Next, as a third example of the present invention, a foil piece produced by a liquid quenching method was modularized and its characteristics were evaluated. Specifically, an ingot having a composition of Bi 2 Te 2.7 Se 0.3 is produced by a method similar to the method for producing the thermoelectric material of the second embodiment described above, and the cooling rate is increased by a liquid quenching method. An n-type thermoelectric material foil piece was produced by making a foil piece at 1 × 10 3 K / second or more. Further, a p-type thermoelectric material foil piece having a composition of Bi 0.4 Sb 1.6 Te 2.9 Se 0.1 was produced by the same method. The thicknesses of these n-type and p-type thermoelectric material foil pieces were both 10 μm. Next, the n-type and p-type thermoelectric material foil pieces were cut into a length of 100 μm and a width of 100 μm using a dicing cutter. Then, the cut thermoelectric material foil piece was mounted on an electrode formed on an alumina substrate having a thickness of 0.1 mm and having a surface coated with solder. Furthermore, an alumina substrate having a thickness of 0.1 mm in which an electrode having solder applied to the surface is formed on the n-type and p-type thermoelectric material foil pieces mounted on the alumina substrate, and the solder surface is a thermoelectric material. After arrange | positioning so that it might become the foil piece side, it heat-pressed, the n-type and p-type thermoelectric material foil piece, and the electrode were joined via the solder, and the thermoelectric module of Example 31 was produced. In addition, the cross-sectional size (substrate size) in this thermoelectric module was 2.6 mm in length and 2.6 mm in width.

また、本実施例の比較例として、実施例３１と同様の方法で作製したｎ型及びｐ型熱電材料箔片を、Ａｒ雰囲気中で、４００℃の温度条件下で２０時間熱処理したものを、実施例３１と同様の方法でアルミナ基板上に実装し、比較例３２の熱電モジュールを作製した。なお、この熱電モジュールにおける横断面サイズ（基板サイズ）も、前述の実施例３１と同様に、縦２．６ｍｍ、横２．６ｍｍとした。   In addition, as a comparative example of this example, n-type and p-type thermoelectric material foil pieces produced by the same method as in Example 31 were heat-treated for 20 hours under a temperature condition of 400 ° C. in an Ar atmosphere. The thermoelectric module of Comparative Example 32 was fabricated by mounting on an alumina substrate in the same manner as in Example 31. In addition, the cross-sectional size (substrate size) in this thermoelectric module was 2.6 mm in length and 2.6 mm in width as in Example 31 described above.

次に、実施例３１の熱電モジュール及び比較例３２の熱電モジュールについて、ｎ型熱電材料箔片の６ｃにおけるＳｅ占有率、温度差ΔＴ及び放熱側基板の温度（Ｔｈ）を２７℃に固定したときの最大吸熱量Ｑｍａｘを測定した。その際、各熱電材料箔片のＳｅ占有率は、Ｘ線チャンネリング分光法により求めた。また、図８は温度差ΔＴの測定方法を模式的に示す断面図であり、図９は最大吸熱量Ｑｍａｘの測定方法を模式的に示す断面図である。図８に示すように、温度差ΔＴの測定では、排熱用ヒートシンク２上に温調用ペルチェモジュール３及び銅板４をこの順に配置し、その上に測定対象の熱電モジュール１を放熱側基板が下側になるようにして配置した。更に、熱電モジュール１の吸熱側基板上に銅板５を配置し、銅板４及び銅板５の略中心部分に夫々放熱側基板温度（Ｔｈ）測定用熱電対６及び吸熱側基板温度（Ｔｃ）測定用熱電対７を取り付けた。そして、温調用ペルチェモジュール３により放熱側基板温度Ｔｈを１００℃に維持しながら、熱電モジュール１に電流を流し、吸熱側基板温度Ｔｃを測定し、放熱側基板温度と吸熱側基板温度との差（Ｔｈ−Ｔｃ）の最大値を温度差ΔＴとした。 Next, with respect to the thermoelectric module of Example 31 and the thermoelectric module of Comparative Example 32, when the Se occupancy, the temperature difference ΔT, and the temperature (Th) of the heat radiation side substrate in 6c of the n-type thermoelectric material foil piece were fixed at 27 ° C. The maximum endothermic amount Q max of was measured. At that time, the Se occupation ratio of each thermoelectric material foil piece was determined by X-ray channeling spectroscopy. FIG. 8 is a cross-sectional view schematically showing a method for measuring the temperature difference ΔT, and FIG. 9 is a cross-sectional view schematically showing a method for measuring the maximum heat absorption amount Qmax . As shown in FIG. 8, in the measurement of the temperature difference ΔT, the temperature adjusting Peltier module 3 and the copper plate 4 are arranged in this order on the exhaust heat sink 2, and the thermoelectric module 1 to be measured is placed on the heat dissipation side substrate on it. Arranged to be on the side. Further, the copper plate 5 is disposed on the heat absorption side substrate of the thermoelectric module 1, and the heat radiation side substrate temperature (Th) measurement thermocouple 6 and the heat absorption side substrate temperature (Tc) measurement are respectively provided at the substantially central portions of the copper plate 4 and the copper plate 5. A thermocouple 7 was attached. Then, while maintaining the heat dissipation side substrate temperature Th at 100 ° C. by the temperature control Peltier module 3, current is passed through the thermoelectric module 1, the heat absorption side substrate temperature Tc is measured, and the difference between the heat dissipation side substrate temperature and the heat absorption side substrate temperature is measured. The maximum value of (Th−Tc) was defined as the temperature difference ΔT.

図９に示すように、最大吸熱量Ｑｍａｘの測定では、排熱用ヒートシンク２上に温調用ペルチェモジュール３及び銅板４をこの順に配置し、その上に測定対象の熱電モジュール１を放熱側基板が下側になるようにして配置した後、熱電モジュール１の吸熱側基板上に銅板５及びヒーター８をこの順に配置し、銅板４及び銅板５に夫々放熱側基板温度（Ｔｈ）測定用熱電対６及び吸熱側基板温度（Ｔｃ）測定用熱電対７を取り付けた。その後、ヒーター８に電力を投入して発熱させ、温調用ペルチェモジュール３により放熱側基板温度Ｔｈ及び吸熱側基板温度Ｔｃを２７℃に維持しながら、熱電モジュール１に電流を流した。そして、ヒーター８の出力を徐々に増加させながら、熱電モジュール１に流す電流を増やし、放熱側基板温度Ｔｈと吸熱側基板温度Ｔｃとが同じになるように調節した。その結果、熱電モジュール１に流す電流を増加させても、放熱側基板温度Ｔｈと吸熱側基板温度Ｔｃとが同じにならなくなったときのヒーター８の出力を最大吸熱量最大吸熱量Ｑｍａｘとした。 As shown in FIG. 9, in the measurement of the maximum heat absorption amount Qmax , the temperature adjusting Peltier module 3 and the copper plate 4 are arranged in this order on the heat sink 2 for exhaust heat, and the thermoelectric module 1 to be measured is placed on the heat dissipation side substrate. Are arranged in such a manner that the copper plate 5 and the heater 8 are arranged in this order on the heat absorption side substrate of the thermoelectric module 1, and the heat radiation side substrate temperature (Th) measurement thermocouples are arranged on the copper plate 4 and the copper plate 5, respectively. 6 and an endothermic substrate temperature (Tc) measuring thermocouple 7 were attached. Thereafter, electric power was supplied to the heater 8 to generate heat, and a current was passed through the thermoelectric module 1 while the temperature adjusting Peltier module 3 maintained the heat radiation side substrate temperature Th and the heat absorption side substrate temperature Tc at 27 ° C. Then, while gradually increasing the output of the heater 8, the current passed through the thermoelectric module 1 was increased, and the heat dissipation side substrate temperature Th and the heat absorption side substrate temperature Tc were adjusted to be the same. As a result, even when the current flowing through the thermoelectric module 1 is increased, the output of the heater 8 when the heat-dissipation-side substrate temperature Th and the heat-absorption-side substrate temperature Tc are not the same is set as the maximum heat absorption amount and the maximum heat absorption amount Qmax . .

Figure 0004479628
Figure 0004479628

上記表３に示すように、液体急冷法により作製した箔片をそのままモジュール化した実施例３１は、ｎ型熱電材料箔片の６ｃサイトにおけるＳｅ占有率が６２％と高く、ＴｅとＳｅとが図１に示す状態のように区別無く置換されているため、液体急冷箔片に熱処理を施したｎ型熱電材料箔片を使用した比較例３２のモジュールに比べて、温度差ΔＴ及び最大吸熱量Ｑｍａｘ共に優れていた。 As shown in Table 3 above, in Example 31 in which the foil piece produced by the liquid quenching method was modularized as it was, the Se occupancy rate at the 6c site of the n-type thermoelectric material foil piece was as high as 62%, and Te and Se were Since it is replaced without distinction as in the state shown in FIG. 1, the temperature difference ΔT and the maximum heat absorption amount are compared with the module of Comparative Example 32 using an n-type thermoelectric material foil piece obtained by heat-treating the liquid quenched foil piece. Both Q max were excellent.

更に、基板の厚さを０．２ｍｍとし、それ以外は実施例３１の熱電モジュールと同じ方法及び条件で実施例３３の熱電モジュールを作製した。そして、これら実施例３１及び実施例３３の熱電モジュール、並びに比較例３４として従来の汎用型の熱電モジュールについて、温度差ΔＴ及び放熱側基板の温度（Ｔｈ）を２７℃に固定したときの最大吸熱量Ｑｍａｘを測定した。なお、比較例３４の従来の汎用型の熱電モジュールにおける断面サイズは、縦２．６ｍｍ、横２．６ｍｍであった。また、温度差ΔＴ及び最大吸熱量Ｑｍａｘは、基板と銅板とをはんだで接合した場合（グリース無）と、基板外面に厚さが２０μｍになるようにグリースを塗布し、その上に銅板を配置した場合（グリース有）との２通りの方法で測定した。以上の結果を下記表４に示す。



Further, the thermoelectric module of Example 33 was manufactured by the same method and conditions as those of the thermoelectric module of Example 31 except that the thickness of the substrate was 0.2 mm. For the thermoelectric modules of Examples 31 and 33 and the conventional general-purpose thermoelectric module as Comparative Example 34, the maximum absorption when the temperature difference ΔT and the temperature (Th) of the heat radiation side substrate are fixed at 27 ° C. The amount of heat Q max was measured. The cross-sectional size of the conventional general-purpose thermoelectric module of Comparative Example 34 was 2.6 mm in length and 2.6 mm in width. The temperature difference ΔT and the maximum heat absorption amount Q max are as follows. When the substrate and the copper plate are joined with solder (no grease), grease is applied to the outer surface of the substrate so that the thickness is 20 μm, and the copper plate is placed thereon. The measurement was carried out by two methods for the case of placement (with grease). The above results are shown in Table 4 below.



Figure 0004479628
Figure 0004479628

上記表４に示すように、実施例３１及び実施例３３の熱電モジュールは、ｎ型熱電材料及びｐ型熱電材料の厚さが薄いため、比較例３４の従来の熱電モジュールに比べて温度差ΔＴは小さいが、最大吸熱量Ｑｍａｘは比較例３４の熱電モジュールに比べて極めて大きかった。但し、熱流を阻害する要因となるため、基板の厚さは薄い方が好ましく、また、ｎ型及びｐ型熱電材料を実装する際にグリースは使用しない方が好ましい。 As shown in Table 4 above, the thermoelectric modules of Example 31 and Example 33 have a temperature difference ΔT compared to the conventional thermoelectric module of Comparative Example 34 because the n-type thermoelectric material and the p-type thermoelectric material are thin. However, the maximum heat absorption amount Q max was extremely large as compared with the thermoelectric module of Comparative Example 34. However, since it becomes a factor that hinders heat flow, it is preferable that the thickness of the substrate is thin, and it is preferable not to use grease when mounting the n-type and p-type thermoelectric materials.

本発明は、小型冷蔵庫及び温度調整器等に使用されるペルチェモジュール用として好適である。   The present invention is suitable for Peltier modules used in small refrigerators, temperature controllers, and the like.

本発明の第１の実施形態の熱電材料の結晶構造の一例を示す図である。It is a figure which shows an example of the crystal structure of the thermoelectric material of the 1st Embodiment of this invention. Ｂｉ２Ｔｅ３の結晶構造を示す図である。Is a diagram showing the crystal structure of Bi 2 Te 3. Ｂｉ２Ｔｅ２Ｓｅの結晶構造を示す図である。It is a diagram showing the crystal structure of Bi 2 Te 2 Se. 横軸にＴｅ量をとり、縦軸に熱伝導率κのうち格子振動（フォノン）による成分κｐｈをとって、Ｓｅ置換量と格子熱伝導率κｐｈとの関係を示すグラフ図である。Take Te amount on the horizontal axis, the lattice vibration of the thermal conductivity kappa vertical axis (phonons) taking component kappa ph by a graph showing the relationship between Se substitution amount and the lattice thermal conductivity kappa ph. 本発明の第２実施形態の熱電材料の製造方法を示すフローチャート図である。It is a flowchart figure which shows the manufacturing method of the thermoelectric material of 2nd Embodiment of this invention. 図１に示す熱電材料のＳｅが再配列した場合の結晶構造を示す図である。It is a figure which shows the crystal structure when Se of the thermoelectric material shown in FIG. 1 rearranges. 横軸に焼結時間をとり、縦軸に焼結温度をとって、固化成形条件と性能指数Ｚとの関係を示すグラフ図である。It is a graph which shows the relationship between solidification molding conditions and the figure of merit Z, taking the sintering time on the horizontal axis and the sintering temperature on the vertical axis. 温度差ΔＴの測定方法を模式的に示す断面図である。It is sectional drawing which shows typically the measuring method of temperature difference (DELTA) T. 最大吸熱量Ｑｍａｘの測定方法を模式的に示す断面図である。The method of measuring the maximum heat absorption amount Q max is a cross-sectional view schematically showing.

符号の説明Explanation of symbols

１；熱電モジュール ２；排熱用ヒートシンク ３；温調用ペルチェモジュール ４、５；銅板 ６、７；熱電対 ８；ヒーター   DESCRIPTION OF SYMBOLS 1; Thermoelectric module 2; Heat sink for waste heat 3; Peltier module for temperature control 4, 5; Copper plate 6, 7; Thermocouple 8;

Claims (3)

ＡをＢｉ及びＳｂからなる群から選択された少なくとも１種の元素としたとき、Ａ２ＴｅｘＳｅ３−ｘで表される組成を有する六方晶系の熱電材料において、マイクロ波焼結法により固化成形され、６ｃサイトのＴｅの一部がＳｅで置換され、Ｓｅが６ｃサイトと３ａサイトに存在する結晶構造を有し、全Ｓｅ量に対して、６ｃサイトに位置しているＳｅの割合が５１原子％以上であることを特徴とする熱電材料。 When A is at least one element selected from the group consisting of Bi and Sb, a hexagonal thermoelectric material having a composition represented by A 2 Te x Se 3-x is obtained by a microwave sintering method. Percentage of Se which is solidified and has a crystal structure in which part of Te at 6c site is replaced by Se, Se is present at 6c site and 3a site, and is located at 6c site with respect to the total amount of Se Is a thermoelectric material characterized in that it is 51 atomic% or more. ＡをＢｉ及びＳｂからなる群から選択された少なくとも１種の元素としたとき、Ａ２ＴｅｘＳｅ３−ｘで表される組成の粉末及び／又は箔片を液体急冷法により冷却速度を１×１０３Ｋ／秒以上にして作製する工程と、前記粉末及び／又は箔片を、焼結時間をｔ（分）とし、焼結温度をＴ（℃）としたとき、下記数式で表される条件で、マイクロ波焼結法により固化成形する工程と、を有し、請求項１に記載の熱電材料を製造することを特徴とする熱電材料の製造方法。
−２５×ｔ＋５７５≦Ｔ＜−１８．８×ｔ＋５７８．１ When A is at least one element selected from the group consisting of Bi and Sb, the cooling rate of powder and / or foil pieces having the composition represented by A 2 Te x Se 3-x is set to 1 by the liquid quenching method. X10 3 K / second or more of the process and the powder and / or the foil piece are expressed by the following formula when the sintering time is t (minutes) and the sintering temperature is T (° C.). And a step of solidifying and molding by a microwave sintering method under the condition of manufacturing the thermoelectric material according to claim 1.
−25 × t + 575 ≦ T <−18.8 × t + 578.1 請求項１に記載の熱電材料が組み込まれていることを特徴とする熱電モジュール。 A thermoelectric module in which the thermoelectric material according to claim 1 is incorporated.
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