JP2006032624A - Thermoelectric transformation material consisting of rhodium oxide - Google Patents
Thermoelectric transformation material consisting of rhodium oxide Download PDFInfo
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- JP2006032624A JP2006032624A JP2004208823A JP2004208823A JP2006032624A JP 2006032624 A JP2006032624 A JP 2006032624A JP 2004208823 A JP2004208823 A JP 2004208823A JP 2004208823 A JP2004208823 A JP 2004208823A JP 2006032624 A JP2006032624 A JP 2006032624A
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本発明は、ロジウム酸化物を用いた熱電変換材料に関し、さらに詳しくは、液体窒素温
度（−１９６℃）以上から１０００℃程度までの広い温度領域にわたって使用可能なロジ
ウム酸化物を用いた熱電変換材料に関する。
The present invention relates to a thermoelectric conversion material using a rhodium oxide, and more specifically, a thermoelectric conversion material using a rhodium oxide that can be used over a wide temperature range from a liquid nitrogen temperature (−196 ° C.) to about 1000 ° C. About.
熱電変換材料を用いた熱電発電（熱電気発電）は、ゼーベック効果すなわち相異なる二
種の金属やｐ型半導体とｎ型半導体等の相異なる熱電変換材料を熱的に並列に置き、電気
的に直列に接続して、接合部間に温度差を与えると両端に熱起電力が発生する熱電効果を
利用して、熱エネルギーを直接電力に変換する技術であり、外部に負荷を接続して閉回路
を構成することにより回路に電流が流れ、電力を取り出すことができることから、僻地用
電源、宇宙用電源、軍事用電源等として一部で実用化されている。
Thermoelectric power generation (thermoelectric power generation) using thermoelectric conversion materials is the Seebeck effect, that is, two different types of metals or different thermoelectric conversion materials such as p-type and n-type semiconductors are placed in parallel and electrically It is a technology that directly converts thermal energy into electric power using the thermoelectric effect that generates thermoelectromotive force at both ends when a temperature difference is applied between the joints when connected in series. Since a current flows through the circuit by configuring the circuit and electric power can be taken out, it has been put to practical use in part as a remote power source, a space power source, a military power source, and the like.
これまで様々な材料が熱電変換材料の候補として合成されてきたが、無次元性能指数Ｚ
Ｔ＝１を大きく上回るものは未だ発見されていない。特に低温度領域すなわち室温付近の
温度領域で有効な熱電変換材料は、何れも性能指数の温度依存性が大きいという問題点が
あった。例えば、ｐ−Ｂｉ２Ｔｅ３（５５）＋Ｓｂ２Ｔｅ３（４５）は優秀な熱電変換材
料であるが、良好な特性を示す温度範囲は３００Ｋ前後と非常に狭い。
So far, various materials have been synthesized as candidates for thermoelectric conversion materials.
Nothing significantly above T = 1 has been found yet. In particular, any thermoelectric conversion material that is effective in a low temperature region, that is, a temperature region near room temperature, has a problem that the temperature dependence of the figure of merit is large. For example, p-Bi 2 Te 3 (55) + Sb 2 Te 3 (45) is an excellent thermoelectric conversion material, but the temperature range showing good characteristics is very narrow at around 300K.
これまで、Ｚ値が最大のもので産業用に用いられている代表的な熱電変換材料はＢｉ２
Ｔｅ３系のものであるが、この材料は融点が低く、有効温度領域は３００Ｋ前後であるの
で、３００℃以上の高温域で用いることはできない。このため、ゼーベック効果を引き起
こす原動力である温度差を大きくとることはできず、熱電変換効率が５〜６％にとどまっ
てしまうという問題点がある。
Until now, the typical thermoelectric conversion material having the largest Z value and used for industrial use is Bi 2.
Although it is a Te 3 type material, since this material has a low melting point and an effective temperature range is around 300 K, it cannot be used in a high temperature range of 300 ° C. or higher. For this reason, the temperature difference which is a driving force causing the Seebeck effect cannot be increased, and there is a problem that the thermoelectric conversion efficiency is limited to 5 to 6%.
また、構成元素であるＴｅの価格がやや高価であり、さらには、Ｂｉ２Ｔｅ３系材料へ
のドーパントとしてＳｂ等の有毒な元素を必要とするため、その製造上及び使用上、毒性
に関する注意が必要であるばかりか、製品が使用終了後に廃棄された場合における環境へ
の影響の点からしても好ましいものではないという問題点がある。
In addition, the price of Te, which is a constituent element, is slightly expensive, and further, a toxic element such as Sb is required as a dopant to the Bi 2 Te 3 system material. In addition, there is a problem that it is not preferable from the viewpoint of environmental impact when the product is disposed after use.
そこで、本発明者等は、従来技術における以上のような人体に対する毒性やコスト的な
問題を解消し、Ｚ値を向上させた熱電変換材料として、元素組成式ＡＣｏｘＯｙ（式中、
Ａは、Ｌｉ、Ｎａ又はＫ、ｘは、１≦ｘ≦２、ｙは、２≦ｙ≦４）で表わされる物質から
なる熱電変換材料、及び、元素組成式（ＡｚＢ１−ｚ）ＣｏｘＯｙ〔式中、Ａは、Ｌｉ、
Ｎａ又はＫ、Ｂは、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｓｃ、Ｙ、Ｂｉ又はＴｅ、ｚは、０＜ｚ＜
１、ｘは、１≦ｘ≦２、ｙは、２≦ｙ≦４〕で表わされる物質からなる熱電変換材料を提
案した（特許文献１）。
Therefore, the present inventors have solved the elemental composition formula ACo x O y (wherein, as a thermoelectric conversion material having solved the above-mentioned toxicity and cost problems for the human body and improved the Z value in the prior art.
A is Li, Na, or K, x is 1 ≦ x ≦ 2, y is 2 ≦ y ≦ 4), and element composition formula (A z B 1-z ) Co x O y [wherein A is Li,
Na or K, B is Mg, Ca, Sr, Ba, Sc, Y, Bi or Te, z is 0 <z <
1 and x have proposed a thermoelectric conversion material made of a material represented by 1 ≦ x ≦ 2 and y is 2 ≦ y ≦ 4] (Patent Document 1).
現在、熱電変換材料として遷移金属酸化物が注目を集め、様々な酸化物、例えば、Ｂｉ
２Ｓｒ２Ｃｏ２Ｏｙ（非特許文献１、２）、Ｂａ０．４Ｓｒ０．５ＰｂＯ３（特許文献２
）、Ｂｉ１．６〜２．２Ｐｂ０〜０．２５Ｓｒ１．１〜２．２Ｃａ０〜０．８Ｃｏ２Ｏ９
−ｘ（０≦ｘ≦１）（特許文献３）、Ａ１−ｘＢｘＰｄ３Ｏ４（ただし、Ａは、Ｃａ，Ｓ
ｒ又はＢａ、Ｂは、Ｌｉ，Ｎａ，Ｋ，Ｓｃ，Ｙ，Ｌａ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｄｙ，
Ｅｒ，Ｈｏ又はＹｂであり、ｘは、０＜ｘ≦１）（特許文献４）などに対して精力的な研
究が行われている。最近、ＮａＣｏ２Ｏ４と同じ結晶構造を持つＳｒｘＲｈ２Ｏ４が発表
され、ＣｏＯ２格子と同じ構造のＲｈＯ２格子の存在が確認された（非特許文献３）。
Currently, transition metal oxides have attracted attention as thermoelectric conversion materials, and various oxides such as Bi
2 Sr 2 Co 2 Oy (Non-patent Documents 1 and 2), Ba 0.4 Sr 0.5 PbO 3 (Patent Document 2)
), Bi 1.6~2.2 Pb 0~0.25 Sr 1.1~2.2 Ca 0~0.8 Co 2 O 9
−x (0 ≦ x ≦ 1) (Patent Document 3), A 1-x B x Pd 3 O 4 (where A is Ca, S
r or Ba and B are Li, Na, K, Sc, Y, La, Nd, Sm, Eu, Gd, Dy,
Er, Ho, or Yb, where x is 0 <x ≦ 1) (Patent Document 4) and the like have been energetically studied. Recently, Sr x Rh 2 O 4 having the same crystal structure as NaCo 2 O 4 was announced, and the existence of the RhO 2 lattice having the same structure as the CoO 2 lattice was confirmed (Non-patent Document 3).
特許文献１に記載された熱電変換材料は、性能指数Ｚ値が比較的高く、しかも、液体窒
素温度から６５０℃以上に及ぶ広い温度範囲にわたって高い熱電変換特性を有し安定に使
用することができ、また、その温度範囲での諸物性値もほぼ一定で優れた物性を有するが
、元素置換などでその熱電特性を制御することが難しく、Ｎａ層でのＮａ不均一や他元素
との固溶が電気伝導を阻害し熱電特性を劣化させてしまう。同じことがＳｒｘＲｈ２Ｏ４
でも言え、Ｓｒの固溶量の違いによって熱電特性が大きく変化する。
The thermoelectric conversion material described in Patent Document 1 has a relatively high figure of merit Z value, and has high thermoelectric conversion characteristics over a wide temperature range from liquid nitrogen temperature to 650 ° C. or more, and can be used stably. In addition, although various physical property values in the temperature range are almost constant and have excellent physical properties, it is difficult to control the thermoelectric properties by element substitution and the like, Na non-uniformity in Na layer and solid solution with other elements Disturbs electrical conduction and degrades thermoelectric properties. The same is true for Sr x Rh 2 O 4
However, the thermoelectric characteristics vary greatly depending on the amount of Sr solid solution.
そのため、本発明は、熱電特性を制御するための元素置換を容易に行え、Ｎａ、Ｓｒ層
のような不安定な要素を持たない材料を提供することを目的とする。
Therefore, an object of the present invention is to provide a material that can easily perform element substitution for controlling thermoelectric characteristics and does not have unstable elements such as Na and Sr layers.
本発明者らは、ＣｏＯ２層ではない熱電性能を高くできる層としてＲｈＯ２層が存在す
ることを突き止めた。このＲｈＯ２は、ＣｏＯ２とは異なったより大きな格子定数を持ち
、元素置換による物性制御に優位に働くことがわかった。本発明の熱電変換材料は、特許
文献３に記載された熱電変換材料の持つＣｏＯ２層よりも大きな格子定数であるＲｈＯ２
層をもつことで、ＣｏＯ２層の小さな格子定数に合致しない原子群に対しても組み合わせ
ることができ、高い熱電機能をもたらすことができた。
The present inventors have found that the RhO 2 layer exists as a layer capable of improving the thermoelectric performance that is not the CoO 2 layer. This RhO 2 has a larger lattice constant different from that of CoO 2, and it has been found that this RhO 2 has an advantage in controlling physical properties by element substitution. The thermoelectric conversion material of the present invention has a lattice constant larger than that of the CoO 2 layer of the thermoelectric conversion material described in Patent Document 3.
By having a layer, it was possible to combine even a group of atoms that did not match the small lattice constant of the CoO 2 layer, and to provide a high thermoelectric function.
すなわち、本発明は、（１）組成式(Ｂｉ１−ａＰｂａ) ２−ｘＭ１２Ｒｈ２−ｙＯｚ
で表されるロジウム酸化物を用いた熱電変換材料（ただし、Ｍ１は、Ｃａ，Ｓｒ又はＢａ
の少なくとも１種、０≦ａ≦０．３、０≦ｘ≦０．３、０≦ｙ≦０．６、６≦ｚ≦８）、
である。
That is, the present invention provides: (1) Composition formula (Bi 1-a Pb a ) 2-x M1 2 Rh 2-y O z
The thermoelectric conversion material using the rhodium oxide represented by (However, M1 is Ca, Sr, or Ba.
At least one of 0 ≦ a ≦ 0.3, 0 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.6, 6 ≦ z ≦ 8),
It is.
また、本発明は、（２）組成式(Ｂｉ１−ａＰｂａ) ２−ｘ(Ｍ１１−ｂＭ２ｂ)２Ｒｈ
２−ｙＯｚで表されるロジウム酸化物を用いた熱電変換材料（ただし、Ｍ１は、Ｃａ，Ｓ
ｒ又はＢａの少なくとも１種、Ｍ２は、Ｍ１とは異なる元素で、Ｃａ，Ｓｒ，Ｂａ，Ｌｉ
，Ｎａ，Ｋ，Ｓｃ，Ｙ，Ｌａ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｄｙ，Ｅｒ，Ｈｏ，又はＹｂの
少なくとも１種で、０≦ａ≦０．３、０≦ｘ≦０．３、０＜ｂ≦０．３、０≦ｙ≦０．６
、６≦ｚ≦８）、である。
In addition, the present invention provides (2) composition formula (Bi 1-a Pb a ) 2-x (M1 1-b M2 b ) 2 Rh
Thermoelectric conversion material using a rhodium oxide represented by 2-y O z (However, M1 is, Ca, S
At least one of r and Ba, M2, is an element different from M1, and is Ca, Sr, Ba, Li.
, Na, K, Sc, Y, La, Nd, Sm, Eu, Gd, Dy, Er, Ho, or Yb, 0 ≦ a ≦ 0.3, 0 ≦ x ≦ 0.3, 0 <B ≦ 0.3, 0 ≦ y ≦ 0.6
6 ≦ z ≦ 8).
また、本発明は、（３）ゼーベック係数が１００〜３００Ｋの温度範囲で７０μＶ/Ｋ
を超えることを特徴とする上記（１）又は（２）の熱電変換材料、である。
Further, the present invention provides (3) 70 μV / K in a temperature range where the Seebeck coefficient is 100 to 300K.
The thermoelectric conversion material according to (1) or (2) above, wherein
上記の課題に記載したように、ＮａＣｏｘＯｙ熱電変換材料のＮａ層による不安定な構
造に代えてより安定な構造にするために、不定比性の低い構造を持つ必要があるが、本発
明者は、その手段として高温超伝導銅酸化物で行われているようなナノブロックインテグ
レーションの考え方に沿って、層構造に岩塩構造を挿入することで元素の不定比性を抑え
つつ、ミスフィツト（misfit）構造を持つことで熱電性能を維持することができることを
見出した。
As described in the above problem, it is necessary to have a structure with low non-stoichiometry in order to make a more stable structure in place of the unstable structure of the NaCo x O y thermoelectric conversion material due to the Na layer. The inventor, in accordance with the idea of nanoblock integration, which is performed with high-temperature superconducting copper oxide as the means, inserts a rock salt structure into the layer structure, while suppressing elemental non-stoichiometry, It was found that thermoelectric performance can be maintained by having a misfit structure.
本発明の熱電変換材料は、１００〜３００Ｋの温度範囲でゼーベック係数が７０μＶ/
Ｋを超える。また、本発明の熱電変換材料は、ゼーベック係数を大きな値に保ちながら、
ブロック層への元素置換を行う場合にブロック層の格子の大きさに柔軟性があるので、イ
オン半径の違いが許容される範囲がより広くなっている点で優れている。
The thermoelectric conversion material of the present invention has a Seebeck coefficient of 70 μV / in a temperature range of 100 to 300K.
K is exceeded. In addition, the thermoelectric conversion material of the present invention, while keeping the Seebeck coefficient at a large value,
When element substitution is performed on the block layer, the size of the lattice of the block layer is flexible, which is excellent in that the range in which the difference in ion radius is allowed is wider.
本発明のＢｉ−（Ｃａ，Ｓｒ，Ｂａ）−Ｒｈ酸化物系複合酸化物からなる料は、ＮａＰ
ｔ３Ｏ４型結晶構造を有し、組成式(Ｂｉ１−ａＰｂａ)２−ｘＭ１２Ｒｈ２−ｙＯｚで表
される。ロジウム酸化物を構成するＲｈ２−ｙＯｚにおいて、ｙは、０≦ｙ≦０．６とし
、ｚは、６≦ｚ≦８とする。ＲｈＯ２層はキャリアの伝導の主たる舞台となり、この層が
高いゼーベック係数を出す中心的構造である。この２次元的な構造を持つ層の間に岩塩構
造という、絶縁体層を挟むことでキャリアの伝導の方向を３次元的にならないようにして
いる。
The material comprising the Bi- (Ca, Sr, Ba) -Rh oxide-based composite oxide of the present invention is NaP.
It has a t 3 O 4 type crystal structure and is represented by a composition formula (Bi 1-a Pb a ) 2−x M1 2 Rh 2−y O z . In Rh 2-y O z constituting the rhodium oxide, y is set to 0 ≦ y ≦ 0.6, z is a 6 ≦ z ≦ 8. The RhO 2 layer is the main stage of carrier conduction, and this layer is a central structure that produces a high Seebeck coefficient. By interposing an insulator layer called a rock salt structure between layers having a two-dimensional structure, the direction of carrier conduction is prevented from becoming three-dimensional.
この種の複合酸化物からなる高温超電導体やＢｉ−（Ｃａ，Ｓｒ，Ｂａ）−Ｃｏ酸化物
系熱電変換材では、希土類元素であるＣａ，Ｓｒ，Ｂａは相互に交換可能な元素として知
られているが、本発明の熱電変換材でもこれらの元素は類似の作用をもたらす。ただし、
このとき、岩塩構造に含まれる希土類元素（Ｃａ，Ｓｒ，Ｂａ）の違いによって、ＲｈＯ
２層間の相互作用が変わり、電気抵抗率に変化が現れる。すなわち、電気抵抗率はイオン
半径の小さいＣａでは絶縁体的に大きくなり、イオン半径の大きなＢａでは金属的に小さ
くなる。
In high-temperature superconductors and Bi- (Ca, Sr, Ba) -Co oxide-based thermoelectric conversion materials made of this type of complex oxide, the rare earth elements Ca, Sr, and Ba are known as mutually interchangeable elements. However, these elements have a similar effect in the thermoelectric conversion material of the present invention. However,
At this time, due to the difference in rare earth elements (Ca, Sr, Ba) contained in the rock salt structure, RhO
The interaction between the two layers changes and changes in electrical resistivity appear. That is, the electrical resistivity increases in an insulating manner with Ca having a small ionic radius and becomes metallic with a Ba having a large ionic radius.
さらに、伝導（ＲｈＯ２)層への元素置換ではなく岩塩層へ元素置換をすることで伝導
層での不純物散乱による伝導の悪化を引き起こさないまま、キャリアを注入することがで
きる。ｙが０．６を超えたり、ｚが６≦ｚ≦８の範囲を外れたりすると結晶ができず好ま
しくない。Ｂｉは、３０原子％までＰｂで置換することができる。Ｐｂで置換することに
よりキャリアとしてホールを注入することができ、ゼーベック係数を大きくすることがで
きる。
Furthermore, by replacing the element in the rock salt layer instead of replacing the element in the conductive (RhO 2 ) layer, carriers can be injected without causing deterioration of conduction due to impurity scattering in the conductive layer. If y exceeds 0.6 or z falls outside the range of 6 ≦ z ≦ 8, crystals cannot be formed, which is not preferable. Bi can be substituted with Pb up to 30 atomic%. By substituting with Pb, holes can be injected as carriers, and the Seebeck coefficient can be increased.
Ｍ１元素であるＣａ，Ｓｒ，Ｂａは、Ｍ１とは異なる元素のＭ２元素、すなわちＣａ，
Ｓｒ，Ｂａ，Ｌｉ，Ｎａ，Ｋ，Ｓｃ，Ｙ，Ｌａ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｄｙ，Ｅｒ，
Ｈｏ，又はＹｂの少なくとも１種をドープすることによって、３０原子％まで置換できる
。すなわち、組成式(Ｂｉ１−ａＰｂａ)２−ｘ(Ｍ１１−ｂＭ２ｂ)２Ｒｈ２−ｙＯｚ（た
だし、Ｍ１は、Ｃａ，Ｓｒ又はＢａの少なくとも１種、Ｍ２は、Ｍ１とは異なる元素で、
Ｃａ，Ｓｒ，Ｂａ，Ｌｉ，Ｎａ，Ｋ，Ｓｃ，Ｙ，Ｌａ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｄｙ，
Ｅｒ，Ｈｏ，又はＹｂの少なくとも１種で、０≦ａ≦０．３、０≦ｘ≦０．３、０＜ｂ≦
０．３、０≦ｙ≦０．６、６≦ｚ≦８の任意の定数である）で表すことができる。Ｍ２元
素で置換することによりキャリア濃度を変化させ、ゼーベック係数を大きくすることがで
きる。
M1, Ca, Sr, and Ba are M2 elements different from M1, that is, Ca,
Sr, Ba, Li, Na, K, Sc, Y, La, Nd, Sm, Eu, Gd, Dy, Er,
By doping at least one of Ho and Yb, substitution can be made up to 30 atomic%. That is, the composition formula (Bi 1-a Pb a ) 2-x (M1 1-b M2 b ) 2 Rh 2-y O z (where M1 is at least one of Ca, Sr or Ba, and M2 is M1 Is an element different from
Ca, Sr, Ba, Li, Na, K, Sc, Y, La, Nd, Sm, Eu, Gd, Dy,
At least one of Er, Ho, or Yb, 0 ≦ a ≦ 0.3, 0 ≦ x ≦ 0.3, 0 <b ≦
0.3, 0 ≦ y ≦ 0.6, 6 ≦ z ≦ 8). By substituting with M2 element, the carrier concentration can be changed and the Seebeck coefficient can be increased.
本発明の熱電変換材料は、原料物質を所定の配合比率で混合し、酸化性雰囲気中で焼成
することによって得ることができる。原料物質は焼成によって目的とする複合酸化物を形
成し得るものであれば特に限定されず、金属単体、酸化物、炭酸塩、硝酸塩、塩化物、水
酸化物、有機金属化合物などの各種化合物を使用できる。
The thermoelectric conversion material of the present invention can be obtained by mixing raw materials at a predetermined blending ratio and firing in an oxidizing atmosphere. The raw material is not particularly limited as long as it can form the desired composite oxide by firing, and various compounds such as simple metals, oxides, carbonates, nitrates, chlorides, hydroxides, and organometallic compounds can be used. Can be used.
焼成手段は特に限定されず、電気加熱炉、ガス加熱炉等によって酸素気流中、空気中な
どの酸化性雰囲気中で焼成する。焼成温度及び焼成時間については、１０００℃程度で１
２時間以上焼成すればよい。１０００℃以上での焼成はＢｉ２Ｏ３の分解を引き起こしＢ
ｉが十分に混入しなくなる。
The firing means is not particularly limited, and firing is performed in an oxygen atmosphere or an oxidizing atmosphere such as air in an electric heating furnace, a gas heating furnace, or the like. About a baking temperature and baking time, it is 1 at about 1000 degreeC.
It may be fired for 2 hours or more. Baking at 1000 ° C. or higher causes decomposition of Bi 2 O 3 and B
i is not sufficiently mixed.
原料として３Ｎの純度のＢｉ２Ｏ３、ＳｒＣＯ３、Ｒｈ２Ｏ３を用い、原料を原子組成
比に合うように全体で３ｇとなるように秤量し３０分以上乳鉢と乳棒で混ぜ合わせた。そ
の後、７８０℃で１２時間熱処理をした。この後、プレス機で成型して円盤状にし、１０
００ ℃で１２時間本焼成を行なった。原子組成比はＢｉ２−ｘＳｒ２Ｒｈ２−yＯｚとし
、ｚ＝７．２、ｘを０．０、０．１、０．２、yを０．０、０．３、０．４、０．５、０
．６、０．３として、図１中に示すｘ、ｙの値の組み合わせからなる９種の組成式の異な
る試料を作製した。
The Bi 2 O 3, SrCO 3, Rh 2 O 3 having a purity of 3N used as the raw material, raw material were combined with weighed 30 minutes or more mortar and pestle such that 3g throughout to fit atomic composition ratio. Thereafter, heat treatment was performed at 780 ° C. for 12 hours. After this, it is molded with a press machine into a disk shape.
The main calcination was performed at 00 ° C. for 12 hours. The atomic composition ratio is Bi 2−x Sr 2 Rh 2−y O z , z = 7.2, x is 0.0, 0.1, 0.2, y is 0.0, 0.3,. 4, 0.5, 0
. Samples with different compositional formulas consisting of combinations of x and y values shown in FIG.
粉末Ｘ線回折では、Ｘ線源としてＣｕ管球を用い、スキャンスピードは２ｄｅｇ/ｍｉ
ｎとして２θが１０ｄｅｇから９０ｄｅｇの範囲で測定した。電気測定の前に、出来あが
った試料を測定するサンプルホルダーに合うように整形した。具体的には、円盤状の焼結
体試料の形状を、カッター、ダイヤモンドやすりを用い幅１．５ｍｍ、長さ１０ｍｍ 、
厚み１ｍｍ 程度の直方体に加工した。
In powder X-ray diffraction, a Cu tube is used as the X-ray source, and the scan speed is 2 deg / mi.
n was measured in the range of 2θ from 10 deg to 90 deg. Prior to electrical measurement, the finished sample was shaped to fit the sample holder to be measured. Specifically, the shape of the disk-shaped sintered body sample is 1.5 mm wide, 10 mm long using a cutter and diamond file,
It was processed into a rectangular parallelepiped with a thickness of about 1 mm.
抵抗率測定には、接触抵抗、計測線の抵抗などが実測の抵抗に重畳しないように４ 端
子法を用いた。端子には銅線を用いた。そのとき端子と試料の電気的接触は銀ペーストを
用いた。測定は４．２Ｋ 〜３００Ｋ まで行なった。専用サンプルホルダーに取り付けた
試料を、液体ヘリウムクライオスタット中で試料を冷却した。そのとき定電流源より試料
に１ｍＡの電流を流し、このときの電圧をナノボルトメータで読み、電流の向きを反転さ
せて再び電圧を読んだ。試料の温度測定には、セルノックス温度計を用い、温度間隔０．
５Ｋで測定を行った。
In the resistivity measurement, a four-terminal method was used so that contact resistance, resistance of the measurement line, and the like were not superimposed on the actually measured resistance. Copper wire was used for the terminal. At that time, silver paste was used for electrical contact between the terminal and the sample. The measurement was performed from 4.2K to 300K. The sample attached to the dedicated sample holder was cooled in a liquid helium cryostat. At that time, a current of 1 mA was passed from the constant current source to the sample, the voltage at this time was read with a nanovoltmeter, the direction of the current was reversed, and the voltage was read again. For the temperature measurement of the sample, a Cellnox thermometer was used, and a temperature interval of 0. 0 was used.
Measurements were taken at 5K.
熱起電力は、定常法により、４．２Ｋから３００Ｋまで測定した。直方体に整形した試
料を、対向した２枚の銅版の間に銀ペースト(Dupont ４９２２N)で取り付け、一方の銅版
をシート抵抗によって加熱することで温度差０．５−１Ｋをつけた。温度差は銅−コンス
タンタン示差熱電対を用いて測定し、試料の温度測定には、セルノックス温度計を用い、
温度間隔２−３ Ｋで測定を行った。熱電対の出力電圧及び試料の熱起電力はナノボルト
メータで読んだ。
The thermoelectromotive force was measured from 4.2K to 300K by a steady method. A sample shaped into a rectangular parallelepiped was attached with a silver paste (Dupont 4922N) between two opposed copper plates, and one copper plate was heated by sheet resistance to give a temperature difference of 0.5-1K. The temperature difference is measured using a copper-constantan differential thermocouple, and the temperature of the sample is measured using a Cellnox thermometer.
Measurement was performed at a temperature interval of 2-3 K. The output voltage of the thermocouple and the thermoelectromotive force of the sample were read with a nanovoltmeter.
図１に、得られたＢｉ２−ｘＳｒ２Ｒｈ２−ｙＯｚの抵抗率ρと熱起電力（ゼーベック
係数Ｓ）の温度依存性を示す。Ｂｉ２−ｘＳｒ２Ｒｈ２−ｙＯｚのｘ、ｙを変化させるこ
とでρは変化しないが、Ｓは１００Ｋ付近で３倍程度変化している。９種の試料は全て、
１００〜３００Ｋの温度範囲で約１００μＶ/Ｋ以上の値を示し、３００Ｋ（室温付近）
でも１００μＶ/Ｋ以上と非常に大きな値を示している。
FIG. 1 shows the temperature dependence of the resistivity ρ and the thermoelectromotive force (Seebeck coefficient S) of the obtained Bi 2-x Sr 2 Rh 2-y O z . By changing x and y of Bi 2 -x Sr 2 Rh 2 -y O z , ρ does not change, but S changes about 3 times around 100K. All nine samples
Shows a value of about 100μV / K or more in the temperature range of 100 to 300K, 300K (near room temperature)
However, it shows a very large value of 100 μV / K or more.
実施例１の方法と同様な方法により、原料にＰｂ２Ｏ３を添加してＰｂでＢｉの１０原
子％及び２０原子％を置換した(Ｂｉ，Ｐｂ)１．８Ｓｒ２Ｒｈ１．６Ｏｚの組成式からな
る試料を作製した。
(Bi, Pb) 1.8 Sr 2 Rh 1.6 O in which Pb 2 O 3 was added to the raw material and 10 atomic% and 20 atomic% of Bi were substituted with Pb by the same method as in Example 1. A sample having the composition formula of z was prepared.
図２に、(Ｂｉ１−ｘＰｂｘ)１．８Ｓｒ２Ｒｈ１．６Ｏｚの抵抗率ρと熱起電力(ゼー
ベック係数)Ｓを示す。ＢｉのサイトにＰｂをわずかに入れることでρは大きくなったが
Ｓも大きくなった。しかし、Ｐｂをより多く入れるとＳは小さくなる。したがって、Ｐｂ
によるＢｉの置換量を３０原子％程度までとすることにより、ゼーベック係数を大きくす
ることができる。
FIG. 2 shows the resistivity ρ and the thermoelectromotive force (Seebeck coefficient) S of (Bi 1-x Pb x ) 1.8 Sr 2 Rh 1.6 O z . By slightly adding Pb to the Bi site, ρ increased, but S also increased. However, if more Pb is added, S becomes smaller. Therefore, Pb
The Seebeck coefficient can be increased by setting the amount of Bi substituted by up to about 30 atomic%.
実施例１の方法と同様な方法により、原料としてＳｒＣＯ３の代わりにＢａＣＯ３を用
いてＢｉ２．０Ｂａ２Ｒｈ２．０Ｏｚの組成式からなる試料を作製した。
A sample having a composition formula of Bi 2.0 Ba 2 Rh 2.0 O z was produced by the same method as in Example 1 using BaCO 3 instead of SrCO 3 as a raw material.
図３に、 Ｂｉ２Ｂａ２Ｒｈ２Ｏｚの抵抗率ρと熱起電力(ゼーベック係数)Ｓを示す。
ρが金属的に小さくなり、１０−１〜１０−２の範囲の値になった。Ｓはやや小さくなっ
たものの、１００Ｋ〜３００Ｋの範囲で約１００μＶ/Ｋという大きな値を保っている。
図４に示すように、電力因子は最大で０．５に達した。Ｂｉ１．８Ｓｒ２Ｒｈ１．６Ｏｚ
と比べると電気抵抗率が小さくなった分に応じて電力因子は大きくなった
FIG. 3 shows the resistivity ρ and the thermoelectromotive force (Seebeck coefficient) S of Bi 2 Ba 2 Rh 2 O z .
ρ became metallic and became a value in the range of 10 −1 to 10 −2 . Although S is slightly reduced, S keeps a large value of about 100 μV / K in the range of 100K to 300K.
As shown in FIG. 4, the power factor reached 0.5 at the maximum. Bi 1.8 Sr 2 Rh 1.6 O z
The power factor increased with the decrease in electrical resistivity
実施例１の方法と同様な方法により、原料に、Ｎａ２ＣＯ３又はＬａ２Ｏ３を添加して
Ｎａ又はＬａでＳｒの１０原子％を置換したＢｉ２Ｓｒ１．８Ｎａ０．２Ｒｈ２Ｏｚ又は
Ｂｉ２Ｓｒ１．８Ｌａ０．２Ｒｈ２Ｏｚの組成式からなる試料を作製した。
Bi 2 Sr 1.8 Na 0.2 Rh in which Na 2 CO 3 or La 2 O 3 was added to the raw material and 10 atomic% of Sr was substituted with Na or La by the same method as in Example 1 A sample having a composition formula of 2 O z or Bi 2 Sr 1.8 La 0.2 Rh 2 O z was prepared.
図５に、Ｂｉ２(Ｓｒ０．９Ｍ２０．１)２Ｒｈ２Ｏｚ(Ｍ２＝Ｎａ，Ｌａ)の抵抗率ρ
と熱起電力(ゼーベック係数)Ｓ を示す。Ｎａ、Ｌａをドープすることでキャリアを注入
したことで、ドープする前よりもＳは小さくなったがρも１０−１程度に小さくなった。
しかし、Ｓは１００Ｋ〜３００Ｋの範囲で約７０μＶ/Ｋ〜９０μＶ/Ｋという大きな値を
保っている。
FIG. 5 shows the resistivity ρ of Bi 2 (Sr 0.9 M2 0.1 ) 2 Rh 2 O z (M2 = Na, La).
And the thermoelectromotive force (Seebeck coefficient) S. Na, by injected carriers by doping La, than before doping S has been reduced becomes smaller in the order of 10 -1 [rho.
However, S maintains a large value of about 70 μV / K to 90 μV / K in the range of 100K to 300K.
Claims (3)
いた熱電変換材料（ただし、Ｍ１は、Ｃａ，Ｓｒ又はＢａの少なくとも１種、０≦ａ≦０
．３、０≦ｘ≦０．３、０≦ｙ≦０．６、６≦ｚ≦８）。 Thermoelectric conversion material using a rhodium oxide represented by a composition formula (Bi 1-a Pb a ) 2−x M1 2 Rh 2−y O z (where M1 is at least one of Ca, Sr, or Ba, 0 ≦ a ≦ 0
. 3, 0 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.6, 6 ≦ z ≦ 8).
ウム酸化物を用いた熱電変換材料（ただし、Ｍ１は、Ｃａ，Ｓｒ又はＢａの少なくとも１
種、Ｍ２は、Ｍ１とは異なる元素で、Ｃａ，Ｓｒ，Ｂａ，Ｌｉ，Ｎａ，Ｋ，Ｓｃ，Ｙ，Ｌ
ａ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｄｙ，Ｅｒ，Ｈｏ，又はＹｂの少なくとも１種、０≦ａ≦
０．３、０≦ｘ≦０．３、０＜ｂ≦０．３、０≦ｙ≦０．６、６≦ｚ≦８）。 Thermoelectric conversion material using a rhodium oxide represented by a composition formula (Bi 1-a Pb a ) 2-x (M1 1-b M2 b ) 2 Rh 2-y O z (where M1 is Ca, Sr Or at least one of Ba
The seed, M2, is an element different from M1, and is Ca, Sr, Ba, Li, Na, K, Sc, Y, L
at least one of a, Nd, Sm, Eu, Gd, Dy, Er, Ho, or Yb, 0 ≦ a ≦
0.3, 0 ≦ x ≦ 0.3, 0 <b ≦ 0.3, 0 ≦ y ≦ 0.6, 6 ≦ z ≦ 8).
請求項１又は２記載の熱電変換材料。 The thermoelectric conversion material according to claim 1 or 2, wherein the Seebeck coefficient exceeds 70 µV / K in a temperature range of 100 to 300K.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010141066A2 (en) * | 2009-06-04 | 2010-12-09 | Office Of Technology Transfer | Fabrication of high-temperature thermoelectric couple |
| CN103579486A (en) * | 2013-11-20 | 2014-02-12 | 遵义师范学院 | Bi85Sb15-xKx (Kalium mixed with bismuth-antimony) low-temperature thermoelectric material and preparing method thereof |
-
2004
- 2004-07-15 JP JP2004208823A patent/JP2006032624A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010141066A2 (en) * | 2009-06-04 | 2010-12-09 | Office Of Technology Transfer | Fabrication of high-temperature thermoelectric couple |
| WO2010141066A3 (en) * | 2009-06-04 | 2011-02-24 | Office Of Technology Transfer | Fabrication of high-temperature thermoelectric couple |
| CN103579486A (en) * | 2013-11-20 | 2014-02-12 | 遵义师范学院 | Bi85Sb15-xKx (Kalium mixed with bismuth-antimony) low-temperature thermoelectric material and preparing method thereof |
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