JP4497981B2 - Thermoelectric material and thermoelectric conversion element - Google Patents
Thermoelectric material and thermoelectric conversion element Download PDFInfo
- Publication number
- JP4497981B2 JP4497981B2 JP2004100812A JP2004100812A JP4497981B2 JP 4497981 B2 JP4497981 B2 JP 4497981B2 JP 2004100812 A JP2004100812 A JP 2004100812A JP 2004100812 A JP2004100812 A JP 2004100812A JP 4497981 B2 JP4497981 B2 JP 4497981B2
- Authority
- JP
- Japan
- Prior art keywords
- density
- thermoelectric material
- thermoelectric
- sintered body
- true density
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000000463 material Substances 0.000 title claims description 88
- 238000006243 chemical reaction Methods 0.000 title claims description 14
- 239000013078 crystal Substances 0.000 claims description 36
- 239000000203 mixture Substances 0.000 claims description 31
- 229910052735 hafnium Inorganic materials 0.000 claims description 17
- 229910052726 zirconium Inorganic materials 0.000 claims description 17
- 229910052719 titanium Inorganic materials 0.000 claims description 16
- 229910052787 antimony Inorganic materials 0.000 claims description 9
- 229910052718 tin Inorganic materials 0.000 claims description 8
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 229910052733 gallium Inorganic materials 0.000 claims description 6
- 229910052745 lead Inorganic materials 0.000 claims description 6
- 229910052749 magnesium Inorganic materials 0.000 claims description 6
- 229910052785 arsenic Inorganic materials 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 229910052738 indium Inorganic materials 0.000 claims description 4
- 229910052715 tantalum Inorganic materials 0.000 claims description 4
- 229910052804 chromium Inorganic materials 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims description 3
- 229910052758 niobium Inorganic materials 0.000 claims description 3
- 229910052721 tungsten Inorganic materials 0.000 claims description 2
- 229910052720 vanadium Inorganic materials 0.000 claims description 2
- 229910045601 alloy Inorganic materials 0.000 description 23
- 239000000956 alloy Substances 0.000 description 23
- 238000000034 method Methods 0.000 description 19
- 238000000465 moulding Methods 0.000 description 18
- 238000002844 melting Methods 0.000 description 14
- 230000008018 melting Effects 0.000 description 14
- 238000010438 heat treatment Methods 0.000 description 11
- 238000005245 sintering Methods 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 239000002994 raw material Substances 0.000 description 10
- 239000010949 copper Substances 0.000 description 9
- 229910005887 NiSn Inorganic materials 0.000 description 8
- 150000001875 compounds Chemical class 0.000 description 8
- 238000010298 pulverizing process Methods 0.000 description 8
- 229910052761 rare earth metal Inorganic materials 0.000 description 8
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 7
- 238000006467 substitution reaction Methods 0.000 description 7
- 239000000470 constituent Substances 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 238000004090 dissolution Methods 0.000 description 5
- 229910000765 intermetallic Inorganic materials 0.000 description 5
- 229910052759 nickel Inorganic materials 0.000 description 5
- 239000000758 substrate Substances 0.000 description 5
- 239000000843 powder Substances 0.000 description 4
- VZSRBBMJRBPUNF-UHFFFAOYSA-N 2-(2,3-dihydro-1H-inden-2-ylamino)-N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]pyrimidine-5-carboxamide Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C(=O)NCCC(N1CC2=C(CC1)NN=N2)=O VZSRBBMJRBPUNF-UHFFFAOYSA-N 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000001747 exhibiting effect Effects 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 230000000171 quenching effect Effects 0.000 description 3
- 229910052727 yttrium Inorganic materials 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 229910052691 Erbium Inorganic materials 0.000 description 2
- MKYBYDHXWVHEJW-UHFFFAOYSA-N N-[1-oxo-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propan-2-yl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(C(C)NC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 MKYBYDHXWVHEJW-UHFFFAOYSA-N 0.000 description 2
- NIPNSKYNPDTRPC-UHFFFAOYSA-N N-[2-oxo-2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 NIPNSKYNPDTRPC-UHFFFAOYSA-N 0.000 description 2
- 229910052797 bismuth Inorganic materials 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 229910002909 Bi-Te Inorganic materials 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 229910018989 CoSb Inorganic materials 0.000 description 1
- 229910052693 Europium Inorganic materials 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 230000005679 Peltier effect Effects 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004993 emission spectroscopy Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000009689 gas atomisation Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- 239000012856 weighed raw material Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Images
Landscapes
- Powder Metallurgy (AREA)
Description
本発明は、ＭｇＡｇＡｓ型結晶構造を有する熱電材料、およびこれを用いた熱電変換素子に関する。 The present invention relates to a thermoelectric material having an MgAgAs crystal structure and a thermoelectric conversion element using the same.
近年、地球環境問題に対する意識の高揚から、フロンレス冷却であるペルチェ効果を利用した熱電冷却素子に関する関心が高まってきている。また、地球温暖化問題から二酸化炭素排出量を削減するために、未利用廃熱エネルギーを電気エネルギーに直接変換する熱電発電素子に対する関心も高まりつつある。 In recent years, interest in thermoelectric cooling elements using the Peltier effect, which is freonless cooling, has increased due to the heightened awareness of global environmental problems. In addition, in order to reduce carbon dioxide emissions due to the global warming problem, there is an increasing interest in thermoelectric power generation elements that directly convert unused waste heat energy into electrical energy.
熱電材料の性能指数Ｚは、下記式（１）式で表される。 The performance index Z of the thermoelectric material is expressed by the following formula (1).
Ｚ＝α2σ／κ（＝Ｐｆ／κ） …（１）
ここで、αは熱電材料のゼーベック係数、σは熱電材料の導電率、κは熱電材料の熱伝導率である。導電率σの逆数は、電気抵抗率ρとして表わされる。またα2×σの項をまとめて出力因子Ｐｆという。Ｚは温度の逆数の次元を有し、この性能指数Ｚに絶対温度を乗ずると無次元の値となる。このＺＴ値は無次元性能指数と呼ばれ、高いＺＴ値を持つ熱電材料ほど熱電変換効率が大きくなる。上記式（１）からわかるように、熱電材料には、より高いゼーベック係数およびより低い電気抵抗率、すなわちより高い出力因子と、低い熱伝導率とが求められる。
Z = α 2 σ / κ (= Pf / κ) (1)
Here, α is the Seebeck coefficient of the thermoelectric material, σ is the conductivity of the thermoelectric material, and κ is the heat conductivity of the thermoelectric material. The reciprocal of conductivity σ is expressed as electrical resistivity ρ. The terms α 2 × σ are collectively referred to as an output factor Pf. Z has a dimension of the reciprocal of temperature, and when this figure of merit Z is multiplied by absolute temperature, it becomes a dimensionless value. This ZT value is called a dimensionless figure of merit, and the thermoelectric conversion efficiency increases as the thermoelectric material has a higher ZT value. As can be seen from the above formula (1), the thermoelectric material is required to have a higher Seebeck coefficient and a lower electrical resistivity, that is, a higher output factor and a lower thermal conductivity.
ＭｇＡｇＡｓ型結晶構造をもつ金属間化合物の一部は半導体的性質を示し、新規熱電材料として注目されている。これらの金属間化合物の熱電性能は構成元素の組み合わせに依存することが報告されている（例えば特許文献１参照）。 Some of the intermetallic compounds having the MgAgAs crystal structure show semiconducting properties and are attracting attention as new thermoelectric materials. It has been reported that the thermoelectric performance of these intermetallic compounds depends on the combination of constituent elements (see, for example, Patent Document 1).
ＭｇＡｇＡｓ型結晶構造を有する金属間化合物であるハーフホイスラー化合物は立方晶系である。ハーフホイスラー化合物は、その構成元素をＭαβで表わすと、元素Ｍおよびβで構成されるＮａＣｌ型結晶格子に元素αが挿入された構造を有する。こうした構造を有するハーフホイスラー化合物は室温で高いゼーベック係数を有する。例えばＺｒＮｉＳｎは、室温で−１７６μＶ／Ｋという高いゼーベック係数を有することが報告されている（例えば、非特許文献１参照）。しかし、ＺｒＮｉＳｎは、室温での抵抗率が１１ｍΩｃｍと大きく、熱伝導率も８．８Ｗ／ｍＫと大きいため、その無次元性能指数ＺＴは０．０１と小さい。 The half-Heusler compound, which is an intermetallic compound having an MgAgAs type crystal structure, is a cubic system. The half-Heusler compound has a structure in which the element α is inserted into a NaCl-type crystal lattice composed of the elements M and β, when the constituent element is represented by Mαβ. A half-Heusler compound having such a structure has a high Seebeck coefficient at room temperature. For example, ZrNiSn has been reported to have a high Seebeck coefficient of −176 μV / K at room temperature (see, for example, Non-Patent Document 1). However, since ZrNiSn has a large resistivity at room temperature of 11 mΩcm and a thermal conductivity of 8.8 W / mK, its dimensionless figure of merit ZT is as small as 0.01.
一方、希土類を含む熱電材料、例えばＨｏＰｄＳｂは熱伝導率が６Ｗ／ｍＫと報告されており、熱伝導率はＺｒＮｉＳｎよりやや小さい（例えば、非特許文献２参照）。しかし、ＨｏＰｄＳｂは、室温におけるゼーベック係数が１５０μＶ／Ｋであり、抵抗率が９ｍΩｃｍと大きいため、その無次元性能指数ＺＴは０．０１に留まる。Ｈｏ0.5Ｅｒ0.5ＰｄＳｂ1.05、Ｅｒ0.25Ｄｙ0.75Ｐｄ1.02ＳｂおよびＥｒ0.25Ｄｙ0.75ＰｄＳｂ1.05でも、室温における無次元性能指数ＺＴはそれぞれ０．０４、０．０３、および０．０２と小さいことが報告されている。 On the other hand, thermoelectric materials containing rare earths, such as HoPdSb, have been reported to have a thermal conductivity of 6 W / mK, and the thermal conductivity is slightly smaller than ZrNiSn (see, for example, Non-Patent Document 2). HoPdSb, however, has a Seebeck coefficient at room temperature of 150 μV / K and a resistivity as large as 9 mΩcm, so its dimensionless figure of merit ZT remains at 0.01. Even with Ho 0.5 Er 0.5 PdSb 1.05 , Er 0.25 Dy 0.75 Pd 1.02 Sb and Er 0.25 Dy 0.75 PdSb 1.05 , the dimensionless figure of merit ZT at room temperature is reported to be as small as 0.04, 0.03 and 0.02, respectively. ing.
以上のように熱電材料では、構成元素の組み合わせによって熱電性能が変化することは多くの文献で報告されている。しかし、従来の熱電材料は十分に高い熱電性能を示すに至っていない。
本発明の目的は、出力因子が比較的大きくかつ十分に低い熱伝導率を有し、高い無次元性能指数ＺＴを示すＭｇＡｇＡｓ型結晶構造の熱電材料、およびこれを用いた熱電変換素子を提供することにある。 An object of the present invention is to provide an MgAgAs-type crystal structure thermoelectric material having a relatively large output factor and sufficiently low thermal conductivity and exhibiting a high dimensionless figure of merit ZT, and a thermoelectric conversion element using the same. There is.
本発明の一態様に係る熱電材料は、下記組成式
（Ｔｉa1Ｚｒb1Ｈｆc1）xαyβ100-x-y
（ここで、０＜a1≦１、０＜b1≦１、０＜c1≦１、a1＋b1＋c1＝１、３０≦ｘ≦３５、３０≦ｙ≦３５、αはＮｉ、βはＳｎであり、βの３０原子％以下がＳｉ，Ｍｇ，Ａｓ，Ｓｂ，Ｂｉ，Ｇｅ，Ｐｂ，ＧａおよびＩｎからなる群より選択される少なくとも一種の元素で置換されている）
で表わされ、ＭｇＡｇＡｓ型結晶相を主相とし、密度が真密度の８１．８〜９９．０％である焼結体からなることを特徴とする。
The thermoelectric material according to one embodiment of the present invention has the following composition formula (Ti a1 Zr b1 Hf c1 ) x α y β 100-xy
(Where, 0 <a1 ≦ 1, 0 <b1 ≦ 1, 0 <c1 ≦ 1, a1 + b1 + c1 = 1,30 ≦ x ≦ 35,30 ≦ y ≦ 35, α is Ni, beta is Ri Sn der, beta 30 atomic% or less Si, Mg, as, Sb, Bi, Ge, Pb, that is substituted with at least one element selected from the group consisting of Ga and in)
It is characterized by comprising a sintered body having a MgAgAs crystal phase as the main phase and a density of 81.8 to 99.0% of the true density.
本発明の他の態様に係る熱電材料は、下記組成式
（Ｔｉ a1 Ｚｒ b1 Ｈｆ c1 ） x αyβ100-x-y
（ここで、０＜a1≦１、０＜b1≦１、０＜c1≦１、a1＋b1＋c1＝１、３０≦ｘ≦３５、３０≦ｙ≦３５、αはＣｏ、βはＳｂであり、βの３０原子％以下がＳｎ,Ｓｉ，Ｍｇ，Ａｓ，Ｂｉ，Ｇｅ，Ｐｂ，ＧａおよびＩｎからなる群より選択される少なくとも一種の元素で置換されている）
で表わされ、ＭｇＡｇＡｓ型結晶相を主相とし、密度が真密度の８１．８〜９９．０％である焼結体からなることを特徴とする。
The thermoelectric material according to another embodiment of the present invention has the following composition formula:
(Ti a1 Zr b1 Hf c1 ) x α y β 100-xy
(Where 0 <a1 ≦ 1, 0 <b1 ≦ 1, 0 <c1 ≦ 1, a1 + b1 + c1 = 1 , 30 ≦ x ≦ 35, 30 ≦ y ≦ 35, α is Co, β is Sb, 30 atomic% or less Sn, Si, Mg, as, Bi, Ge, Pb, that is substituted with at least one element selected from the group consisting of Ga and in)
It is characterized by comprising a sintered body having a MgAgAs crystal phase as the main phase and a density of 81.8 to 99.0% of the true density.
本発明のさらに他の態様に係る熱電変換素子は、交互に直列に接続されたｐ型熱電材料およびｎ型熱電材料を含み、前記ｐ型熱電材料および前記ｎ型熱電材料の少なくとも一方は前記熱電材料を含むことを特徴とする。 A thermoelectric conversion element according to still another aspect of the present invention includes a p-type thermoelectric material and an n-type thermoelectric material alternately connected in series, and at least one of the p-type thermoelectric material and the n-type thermoelectric material is the thermoelectric material. Including material.
本発明によれば、比較的高い出力因子と十分に低い熱伝導率を有し、大きな無次元性能指数ＺＴを示す熱電材料を提供することができる。このような熱電材料を用いることによって、高性能の熱電変換素子、熱電変換モジュールを容易に作製することが可能となり、その工業的価値は大きい。 According to the present invention, it is possible to provide a thermoelectric material having a relatively high output factor and sufficiently low thermal conductivity and exhibiting a large dimensionless figure of merit ZT. By using such a thermoelectric material, it becomes possible to easily produce a high-performance thermoelectric conversion element and thermoelectric conversion module, and its industrial value is great.
まず、本明細書において用いる用語の定義について説明する。本明細書において、主相とは、構成される結晶相のうち最も体積分率の高い結晶相のことをいう。本明細書において、真密度とは、溶解により製造された、内部に空隙のない熱電材料の試料の体積と重量を実測することにより求めた密度のことをいう。 First, definitions of terms used in this specification will be described. In this specification, the main phase means a crystal phase having the highest volume fraction among the constituted crystal phases. In the present specification, the true density refers to a density obtained by actually measuring the volume and weight of a sample of a thermoelectric material that is manufactured by melting and has no voids inside.
前記（１）式を参照して説明したように、熱電材料は、出力因子が高く熱伝導率が小さいほど、無次元性能指数が高く優れた性能を示す。熱電材料の出力因子や熱伝導率は、構成元素、結晶構造、組織形態などに依存すると考えられる。 As described with reference to the equation (1), the thermoelectric material has a higher dimensionless figure of merit and an excellent performance as the output factor is higher and the thermal conductivity is lower. It is considered that the output factor and thermal conductivity of the thermoelectric material depend on the constituent elements, crystal structure, structure form, and the like.
本発明者らは、ＭｇＡｇＡｓ型結晶構造をもつ金属間化合物において、その密度を真密度より低くすることによって、出力因子Ｐｆ（＝α2／ρ）を維持したまま、熱伝導率を低減できることを見出した。一般的には、材料の密度を低くすると、その材料の熱伝導率は低下する。また、材料の密度を低くすると、その材料の電気伝導率も低下する。一方、ＭｇＡｇＡｓ型結晶構造を有する金属間化合物は、真密度より低い密度（真密度の７０.０〜９９.０％）を有するときに、ゼーベック係数の絶対値が増加する場合があることを見出した。ゼーベック係数はフェルミ面付近のバンド構造によって決まると言われている。しかし、密度が低く内部に空孔などが存在する材料では、真密度を示す完全に充填された材料と異なるバンド構造が現れるため、ゼーベック係数も密度によって変化する可能性がある。本発明の実施形態に係る熱電材料においてゼーベック係数が増加するのはこのことを反映しているものと考えられる。 The inventors of the present invention show that, in an intermetallic compound having an MgAgAs type crystal structure, the thermal conductivity can be reduced while maintaining the output factor Pf (= α 2 / ρ) by making the density lower than the true density. I found it. Generally, when the density of a material is lowered, the thermal conductivity of the material is lowered. Further, when the density of the material is lowered, the electrical conductivity of the material is also lowered. On the other hand, an intermetallic compound having an MgAgAs crystal structure has been found to have an increase in the absolute value of the Seebeck coefficient when the density is lower than the true density (70.0 to 99.0% of the true density). It was. The Seebeck coefficient is said to be determined by the band structure near the Fermi surface. However, in a material having a low density and having pores or the like inside, a band structure different from that of a completely filled material exhibiting a true density appears, so that the Seebeck coefficient may also vary depending on the density. The increase in the Seebeck coefficient in the thermoelectric material according to the embodiment of the present invention is considered to reflect this.
このように、ＭｇＡｇＡｓ型結晶相を主相とする熱電材料では、その密度を真密度の７０.０〜９９.０％とすることにより、出力因子（ゼーベック係数の２乗×電気伝導率）の低下を抑えつつ熱伝導率だけを低下させることができるため、無次元性能指数ＺＴを増加させることができる。 As described above, in the thermoelectric material having the MgAgAs type crystal phase as the main phase, by setting the density to 70.0 to 99.0% of the true density, the output factor (the square of the Seebeck coefficient × electric conductivity) Since only the thermal conductivity can be reduced while suppressing the reduction, the dimensionless figure of merit ZT can be increased.
本発明の一実施形態に係る熱電材料は下記組成式（Ａ）で表され、ＭｇＡｇＡｓ型結晶相を主相とするハーフホイスラー化合物であり、その密度が真密度の７０.０〜９９.０％である。 A thermoelectric material according to an embodiment of the present invention is a half-Heusler compound represented by the following composition formula (A) and having a MgAgAs crystal phase as a main phase, and the density is 70.0 to 99.0% of the true density. It is.
（Ｔｉa1Ｚｒb1Ｈｆc1）xαyβ100-x-y …（Ａ）
（ここで、０≦a1≦１、０≦b1≦１、０≦c1≦１、a1＋b1＋c1＝１、３０≦ｘ≦３５、３０≦ｙ≦３５、αはＮｉおよびＣｏから選択される少なくとも一種の元素、βはＳｎおよびＳｂから選択される少なくとも一種の元素である）。
(Ti a1 Zr b1 Hf c1 ) x α y β 100-xy (A)
(Where 0 ≦ a1 ≦ 1, 0 ≦ b1 ≦ 1, 0 ≦ c1 ≦ 1, a1 + b1 + c1 = 1, 30 ≦ x ≦ 35, 30 ≦ y ≦ 35, α is at least one selected from Ni and Co Element, β is at least one element selected from Sn and Sb).
本発明の実施形態に係る熱電材料は、その構成元素をＭαβで表わしたとき、Ｍサイトの元素としてＴｉ、Ｚｒ、Ｈｆを用いることにより熱伝導率を低下させることができる。また、ＭサイトにＴｉ、ＺｒおよびＨｆのうち２つ以上の元素を用いることによって原子半径および原子量の不均一性によるフォノンの散乱を生じさせて、熱伝導率を大幅に低減させることができる。さらに、本発明者らは、ＭサイトにＴｉ、ＺｒおよびＨｆの全てを用いると、ゼーベック係数の増加に効果があることを見出した。Ｔｉ、ＺｒおよびＨｆの全てを含む組成式（Ａ）の熱電材料では、フェルミ面近傍における電子密度分布に急峻な変化が生じていることが考えられる。 When the constituent element of the thermoelectric material according to the embodiment of the present invention is represented by Mαβ, the thermal conductivity can be lowered by using Ti, Zr, and Hf as the elements of the M site. Further, by using two or more elements of Ti, Zr and Hf at the M site, phonon scattering due to nonuniformity of atomic radius and atomic weight can be caused, and the thermal conductivity can be greatly reduced. Furthermore, the present inventors have found that using all of Ti, Zr and Hf at the M site is effective in increasing the Seebeck coefficient. In the thermoelectric material of the composition formula (A) including all of Ti, Zr, and Hf, it is considered that an abrupt change occurs in the electron density distribution near the Fermi surface.
元素Ｍの組成ｘおよび元素αの組成ｙの範囲は、それぞれ３０≦ｘ≦３５および３０≦ｙ≦３５であることが好ましい。ｘおよびｙのより好ましい範囲は、それぞれ３３≦ｘ≦３４および３３≦ｙ≦３４である。上記の範囲を逸脱すると、ＭｇＡｇＡｓ結晶相以外の結晶相が析出してゼーベック係数を損なうおそれがある。 The ranges of the composition x of the element M and the composition y of the element α are preferably 30 ≦ x ≦ 35 and 30 ≦ y ≦ 35, respectively. More preferable ranges of x and y are 33 ≦ x ≦ 34 and 33 ≦ y ≦ 34, respectively. When deviating from the above range, a crystal phase other than the MgAgAs crystal phase may be precipitated to impair the Seebeck coefficient.
本発明の他の実施形態に係る熱電材料は下記組成式（Ｂ）で表わされ、ＭｇＡｇＡｓ型結晶相を主相とするハーフホイスラー化合物であり、その密度が真密度の７０.０〜９９.０％である。 A thermoelectric material according to another embodiment of the present invention is a half-Heusler compound represented by the following composition formula (B) and having an MgAgAs type crystal phase as a main phase, and the density is 70.0 to 99. 0%.
（Ｌｎd（Ｔｉa2Ｚｒb2Ｈｆc2）1-d）xαyβ100-x-y …（Ｂ）
（ここで、ＬｎはＹおよび希土類元素からなる群より選択される少なくとも一種の元素、０≦a2≦１、０≦b2≦１、０≦c2≦１、a2＋b2＋c2＝１、０＜ｄ≦０．３、３０≦ｘ≦３５、３０≦ｙ≦３５、αはＮｉおよびＣｏから選択される少なくとも一種の元素、βはＳｎおよびＳｂから選択される少なくとも一種の元素である）。
(Ln d (Ti a2 Zr b2 Hf c2) 1-d) x α y β 100-xy ... (B)
(Here, Ln is at least one element selected from the group consisting of Y and rare earth elements, 0 ≦ a2 ≦ 1, 0 ≦ b2 ≦ 1, 0 ≦ c2 ≦ 1, a2 + b2 + c2 = 1, 0 <d ≦ 0. 3, 30 ≦ x ≦ 35, 30 ≦ y ≦ 35, α is at least one element selected from Ni and Co, and β is at least one element selected from Sn and Sb).
本発明者らは、組成式（Ａ）で表されるハーフホイスラー化合物Ｍαβ（Ｍ＝Ｔｉ，Ｚｒ，Ｈｆ）における元素Ｍの一部を、Ｔｉ，Ｚｒ，Ｈｆのいずれよりも原子半径が大きい、Ｙおよび希土類元素からなる群より選択される少なくとも一種の元素で置換することによって、熱伝導率を改善できることを見出した。このように、Ｌｎ（Ｙ，希土類元素）は、熱電材料の熱伝導率を低減するのに有効な元素である。Ｌｎのうち希土類元素には周期律表における原子番号５７のＬａから原子番号７１のＬｕまでの全ての元素が含まれる。融点および原子半径を考慮すると、ＬｎとしてはＥｒ，ＧｄおよびＮｄが特に好ましい。 The inventors have a part of the element M in the half-Heusler compound Mαβ (M = Ti, Zr, Hf) represented by the composition formula (A) having a larger atomic radius than any of Ti, Zr, and Hf. It has been found that the thermal conductivity can be improved by substitution with at least one element selected from the group consisting of Y and rare earth elements. Thus, Ln (Y, rare earth element) is an element effective for reducing the thermal conductivity of the thermoelectric material. Among the Ln, the rare earth element includes all elements from La of atomic number 57 to Lu of atomic number 71 in the periodic table. Considering the melting point and the atomic radius, Er, Gd, and Nd are particularly preferable as Ln.
Ｌｎは少量でもその効果を発揮するが、熱伝導率をより低減するためには、Ｌｎの配合量をＬｎとＭ（Ｔｉ，Ｚｒ，Ｈｆ）との総量の０．１原子％以上とすることが好ましい。Ｌｎの配合量が、ＬｎとＭ（Ｔｉ，Ｚｒ，Ｈｆ）との総量の３０原子％を超えた場合には、ＭｇＡｇＡｓ型結晶相以外の結晶相、例えばＬｎＳｎ3相の析出が顕著になって、ゼーベック係数の劣化を招くおそれがある。このため、ｄの範囲は０＜ｄ≦０．３とすることが好ましく、０．００１≦ｄ≦０．３とすることがより好ましい。 Ln exhibits its effect even in a small amount, but in order to further reduce the thermal conductivity, the amount of Ln should be 0.1 atomic% or more of the total amount of Ln and M (Ti, Zr, Hf). Is preferred. When the compounding amount of Ln exceeds 30 atomic% of the total amount of Ln and M (Ti, Zr, Hf), precipitation of crystal phases other than the MgAgAs type crystal phase, for example, LnSn 3 phase becomes remarkable. The Seebeck coefficient may be deteriorated. For this reason, the range of d is preferably 0 <d ≦ 0.3, and more preferably 0.001 ≦ d ≦ 0.3.
前記組成式（Ｂ）で表される熱電材料においても、ｘおよびｙの範囲はそれぞれ３０≦ｘ≦３５および３０≦ｙ≦３５であることが好ましい。組成式（Ａ）で表される熱電材料と同様に、上記の範囲を逸脱すると、ＭｇＡｇＡｓ結晶相以外の結晶相が析出してゼーベック係数を損なうおそれがある。 Also in the thermoelectric material represented by the composition formula (B), the ranges of x and y are preferably 30 ≦ x ≦ 35 and 30 ≦ y ≦ 35, respectively. Similarly to the thermoelectric material represented by the composition formula (A), if the above-mentioned range is deviated, a crystal phase other than the MgAgAs crystal phase may be precipitated to impair the Seebeck coefficient.
ハーフホイスラー化合物においては、総価電子数が１８近傍である場合に大きなゼーベック係数が観測される。例えば、ＺｒＮｉＳｎにおける外殻電子配置は、Ｚｒ（５ｄ2６ｓ2）、Ｎｉ（３ｄ8４ｓ2）、Ｓｎ（５ｓ2５ｐ2）であり、価電子の総数は１８となる。ＴｉＮｉＳｎおよびＨｆＮｉＳｎも同様に、価電子の総数は１８となる。これに対して、組成式（Ｂ）で表わされるように元素Ｍ（Ｔｉ，Ｚｒ，Ｈｆ）の一部を希土類元素で置換した場合、外殻電子配置が（５ｄ1６ｓ2）である希土類元素（Ｃｅ，Ｅｕ，Ｙｂを除く）を含むハーフホイスラー化合物では総価電子数が１８からずれてしまうおそれがある。そこで、ｘおよびｙを適宜調整してこれを補うことが好ましい。 In the half-Heusler compound, a large Seebeck coefficient is observed when the total valence electron number is around 18. For example, the outer electron arrangement in ZrNiSn is Zr (5d 2 6s 2 ), Ni (3d 8 4s 2 ), Sn (5s 2 5p 2 ), and the total number of valence electrons is 18. Similarly for TiNiSn and HfNiSn, the total number of valence electrons is 18. On the other hand, when a part of the element M (Ti, Zr, Hf) is substituted with a rare earth element as represented by the composition formula (B), the rare earth element whose outer shell electron configuration is (5d 1 6s 2 ) In a half-Heusler compound containing (except for Ce, Eu, Yb), the total valence electron number may deviate from 18. Therefore, it is preferable to compensate for this by appropriately adjusting x and y.
本発明の実施形態においては、前記組成式（Ａ）または（Ｂ）における元素Ｍ（Ｔｉ，Ｚｒ，Ｈｆ）の一部を、Ｖ，Ｎｂ，Ｔａ，Ｃｒ，ＭｏおよびＷからなる群より選択される少なくとも一種の元素Ｍ’で置換してもよい。元素Ｍ’は単独でまたは２種以上組み合わせて用いることができる。元素Ｍの一部を元素Ｍ’で置換することによって、主相であるＭｇＡｇＡｓ型結晶相の総価電子数を調整して、ゼーベック係数を増大させたり電気抵抗率を低下させたりすることができる。また、元素Ｍ’と希土類元素とを併用することによって、総価電子数が１８近傍になるように総価電子数を調整することによっても、ゼーベック係数を増大させることができる。ただし、元素Ｍ’の置換量は元素Ｍ（Ｔｉ，Ｚｒ，Ｈｆ）の３０原子％以下とすることが好ましい。元素Ｍ’の置換量が３０原子％を超えると、ＭｇＡｇＡｓ型結晶相以外の結晶相が析出して、ゼーベック係数の劣化を招くおそれがある。 In an embodiment of the present invention, a part of the element M (Ti, Zr, Hf) in the composition formula (A) or (B) is selected from the group consisting of V, Nb, Ta, Cr, Mo and W. May be substituted with at least one element M ′. The element M ′ can be used alone or in combination of two or more. By substituting a part of the element M with the element M ′, the total valence electron number of the MgAgAs crystal phase that is the main phase can be adjusted, and the Seebeck coefficient can be increased or the electrical resistivity can be decreased. . Also, the Seebeck coefficient can be increased by adjusting the total valence electron number so that the total valence electron number is approximately 18 by using the element M ′ and the rare earth element in combination. However, the substitution amount of the element M ′ is preferably 30 atomic% or less of the element M (Ti, Zr, Hf). When the substitution amount of the element M ′ exceeds 30 atomic%, a crystal phase other than the MgAgAs type crystal phase is precipitated, which may cause deterioration of the Seebeck coefficient.
本発明の実施形態においては、前記組成式（Ａ）または（Ｂ）における元素α（Ｎｉ，Ｃｏ）の一部を、Ｍｎ，Ｆｅ，ＣｏおよびＣｕからなる群より選択される少なくとも一種の元素α’で置換してもよい。元素α’は、単独でまたは２種以上を組み合わせて用いることができる。元素αの一部を元素α’で置換することによって、主相であるＭｇＡｇＡｓ型結晶相の総価電子数を調整するなどしてゼーベック係数を増大させたり、電気抵抗率を低下させたりすることができる。元素α’の置換量は、一般的には、元素αの５０原子％以下にすることが好ましい。特に、元素αの一部をＣｕで置換する場合にＣｕが多すぎるとＭｇＡｇＡｓ型結晶相の生成を阻害するおそれがあるため、Ｃｕの置換量は元素αの３０原子％以下にすることがより好ましい。 In an embodiment of the present invention, a part of the element α (Ni, Co) in the composition formula (A) or (B) is at least one element α selected from the group consisting of Mn, Fe, Co, and Cu. It may be replaced with '. The element α ′ can be used alone or in combination of two or more. By replacing part of the element α with the element α ′, the Seebeck coefficient is increased or the electrical resistivity is decreased by adjusting the total number of valence electrons of the MgAgAs crystal phase that is the main phase. Can do. In general, the substitution amount of the element α ′ is preferably 50 atomic% or less of the element α. In particular, when a part of the element α is substituted with Cu, if there is too much Cu, the formation of the MgAgAs crystal phase may be hindered. Therefore, the substitution amount of Cu should be 30 atomic% or less of the element α. preferable.
本発明の実施形態においては、前記組成式（Ａ）または（Ｂ）における元素β（Ｓｎ，Ｓｂ）の一部を、Ｓｉ，Ｍｇ，Ａｓ，Ｓｂ，Ｂｉ，Ｇｅ，Ｐｂ，ＧａおよびＩｎからなる群より選択される少なくとも一種の元素β’で置換してもよい。元素β’は、単独でまたは２種以上を組み合わせて用いることができる。元素βの一部を元素β’で置換することによって、主相であるＭｇＡｇＡｓ型結晶相の総価電子数を調整するなどしてゼーベック係数を増大させたり、電気抵抗率を低下させたりすることができる。元素β’は、有害性、有毒性、材料コストを考慮すると、ＳｉおよびＢｉから選択することが特に好ましい。元素β’の置換量は、元素βの３０原子％以下とすることが好ましい。元素β’の置換量が３０原子％を超えた場合には、ＭｇＡｇＡｓ型結晶相以外の結晶相が析出して、ゼーベック係数の劣化を招くおそれがある。 In an embodiment of the present invention, a part of the element β (Sn, Sb) in the composition formula (A) or (B) is made of Si, Mg, As, Sb, Bi, Ge, Pb, Ga, and In. It may be substituted with at least one element β ′ selected from the group. The element β ′ can be used alone or in combination of two or more. By replacing part of element β with element β ′, the Seebeck coefficient is increased or the electrical resistivity is decreased by adjusting the total number of valence electrons of the MgAgAs crystal phase that is the main phase. Can do. The element β ′ is particularly preferably selected from Si and Bi in consideration of harmfulness, toxicity, and material cost. The substitution amount of the element β ′ is preferably 30 atomic% or less of the element β. When the substitution amount of the element β ′ exceeds 30 atomic%, a crystal phase other than the MgAgAs type crystal phase is precipitated, which may cause deterioration of the Seebeck coefficient.
本発明の実施形態に係る熱電材料は、例えば以下のような方法により製造することができる。 The thermoelectric material which concerns on embodiment of this invention can be manufactured by the following methods, for example.
まず、所定量の各元素を含有する合金を、アーク溶解や高周波溶解などによって作製する。合金の作製に当たっては、単ロール法、双ロール法、回転ディスク法、ガスアトマイズ法などの液体急冷法などを採用することもできる。液体急冷法は合金を構成する結晶相を微細化する、結晶相内への元素の固溶域を拡大するなどの点で有利であり、熱伝導率を低減するのに寄与する。 First, an alloy containing a predetermined amount of each element is produced by arc melting or high frequency melting. In producing the alloy, a liquid quenching method such as a single roll method, a twin roll method, a rotating disk method, or a gas atomizing method may be employed. The liquid quenching method is advantageous in that the crystal phase constituting the alloy is refined and the solid solution region of the element in the crystal phase is expanded, which contributes to reducing the thermal conductivity.
作製された合金に対して、必要に応じて熱処理を施してもよい。この熱処理によって合金が単相化され、結晶粒子径も制御されるので、熱電特性をさらに高めることができる。溶解、液体急冷、および熱処理などの工程は、合金の酸化を防止するという観点から、例えばＡｒなどの不活性雰囲気中で行うことが好ましい。 You may heat-process with respect to the produced alloy as needed. This heat treatment makes the alloy single phase and the crystal grain size is also controlled, so that the thermoelectric characteristics can be further enhanced. From the viewpoint of preventing oxidation of the alloy, the steps such as melting, liquid quenching, and heat treatment are preferably performed in an inert atmosphere such as Ar.
次に、合金をボールミル、ブラウンミル、スタンプミルなどにより粉砕して合金粉末を得た後、合金粉末を焼結法、ホットプレス法、ＳＰＳ法などによって一体成形する。合金の酸化を防止するという観点から、一体成形は例えばＡｒなどの不活性雰囲気中で行うことが好ましい。 Next, the alloy is pulverized by a ball mill, brown mill, stamp mill or the like to obtain an alloy powder, and then the alloy powder is integrally formed by a sintering method, a hot press method, an SPS method, or the like. From the viewpoint of preventing the oxidation of the alloy, the integral molding is preferably performed in an inert atmosphere such as Ar.
従来は、この一体成形工程において、ほぼ真密度を持つ熱電材料を得るような条件を採用していた。あるいは溶解後の合金や溶解後に熱処理を施した合金をそのまま採用していた。これに対して、本発明の実施形態では、一体成形工程の条件を制御することによって熱電材料内部に空隙などをつくり、真密度より低い密度を持つ熱電材料を作製する。例えば、一体成形時の成形荷重、成形温度、成形時間を制御することによって焼結体の密度を調整することができる。なお、ここまでの段階で、溶解や熱処理の条件を調整するだけでは熱電材料の密度を制御するのは難しい。 Conventionally, conditions for obtaining a thermoelectric material having a substantially true density have been employed in this integral molding process. Or the alloy after melt | dissolution and the alloy which heat-processed after melt | dissolution were employ | adopted as it was. On the other hand, in the embodiment of the present invention, voids and the like are created in the thermoelectric material by controlling the conditions of the integral molding process, and a thermoelectric material having a density lower than the true density is produced. For example, the density of the sintered body can be adjusted by controlling the molding load, molding temperature, and molding time during integral molding. It should be noted that it is difficult to control the density of the thermoelectric material only by adjusting the conditions of dissolution and heat treatment at this stage.
本発明の実施形態において、熱電材料の密度を真密度の７０.０〜９９.０％の範囲に調整する方法についてより具体的に説明する。例えば合金粉末をホットプレス法により成形する場合、成形時間を１時間に固定し、成形圧力をＰ（ＭＰａ）、成形温度をＴ（℃）とするとき、下記式（２）
−０.３５Ｔ＋３１０≦Ｐ≦−０.３５Ｔ＋４５０ …（２）
を満たす条件では成形体の密度を真密度の７０.０〜９９.０％とすることができる。より好ましい成形体密度の範囲は８５.０〜９５.０％であり、さらに好ましくは９０.０〜９５.０％である。下記式（３）
−０．３５Ｔ＋３８０≦Ｐ≦−０．３５Ｔ＋４２５ …（３）
を満たす条件では成形体の密度を真密度の８５.０〜９５.０％とすることができ、より性能の高い熱電材料を製造することができる。また、下記式（４）
−０．３５Ｔ＋４１０≦Ｐ≦−０．３５Ｔ＋４２５ …（４）
を満たす条件では成形体の密度を真密度の９０.０〜９５.０％とすることができ、さらに性能を高めることができる。
In the embodiment of the present invention, a method for adjusting the density of the thermoelectric material to a range of 70.0 to 99.0% of the true density will be described more specifically. For example, when the alloy powder is molded by the hot press method, when the molding time is fixed to 1 hour, the molding pressure is P (MPa), and the molding temperature is T (° C.), the following formula (2)
−0.35T + 310 ≦ P ≦ −0.35T + 450 (2)
Under the conditions satisfying the above, the density of the molded body can be 70.0 to 99.0% of the true density. A more preferable range of the molded body density is 85.0 to 95.0%, and further preferably 90.0 to 95.0%. Following formula (3)
−0.35T + 380 ≦ P ≦ −0.35T + 425 (3)
Under the conditions satisfying, the density of the molded body can be 85.0 to 95.0% of the true density, and a thermoelectric material with higher performance can be manufactured. Moreover, following formula (4)
−0.35T + 410 ≦ P ≦ −0.35T + 425 (4)
If the condition is satisfied, the density of the molded body can be 90.0 to 95.0% of the true density, and the performance can be further improved.
これに対して、Ｐ＜−０．３５Ｔ＋３１０という条件では、成形体の密度が７０.０％を下回る。成形体の密度が真密度の７０.０％を下回ると導電率の低下が著しくなるため高いＺ値が得られない。一方、Ｐ＞−０．３５Ｔ＋４５０という条件では成形体の密度が９９.０％を超える。成形体の密度が９９.０％を超えるとゼーベック係数が低下するため高いＺ値が得られない。 On the other hand, on the condition of P <−0.35T + 310, the density of the molded body is less than 70.0%. When the density of the molded body is less than 70.0% of the true density, the electrical conductivity is significantly reduced, and thus a high Z value cannot be obtained. On the other hand, the density of the molded body exceeds 99.0% under the condition of P> −0.35T + 450. If the density of the molded body exceeds 99.0%, the Seebeck coefficient decreases, so that a high Z value cannot be obtained.
成形体の形状や寸法は適宜選択することができる。例えば、外径０．５〜１０ｍｍφで厚み１〜３０ｍｍの円柱状や、０．５〜１０ｍｍ角で厚み１〜３０ｍｍの直方体状などとすることができる。 The shape and dimensions of the molded body can be appropriately selected. For example, it can be a cylindrical shape with an outer diameter of 0.5 to 10 mmφ and a thickness of 1 to 30 mm, or a rectangular parallelepiped shape with a thickness of 0.5 to 10 mm and a thickness of 1 to 30 mm.
次いで、得られた成形体を所望の寸法に加工する。成形体の形状や寸法は適宜選択することができる。例えば、外径０．５〜１０ｍｍφで厚み１〜３０ｍｍの円柱状や、０．５〜１０ｍｍ角で厚み１〜３０ｍｍの直方体状などとすることができる。 Next, the obtained molded body is processed into a desired dimension. The shape and dimensions of the molded body can be appropriately selected. For example, it can be a cylindrical shape with an outer diameter of 0.5 to 10 mmφ and a thickness of 1 to 30 mm, or a rectangular parallelepiped shape with a thickness of 0.5 to 10 mm and a thickness of 1 to 30 mm.
以上のような方法を用いて得られた熱電材料を用いて、本発明の実施形態に係る熱電変換素子を製造することができる。この際、本発明の実施形態に係る熱電材料のうちｎ型もしくはｐ型のいずれか一方または両方を用いて熱電変換素子を製造することができる。ｎ型またはｐ型のいずれか一方のみに本発明の実施形態に係る熱電材料を用いる場合、他方にはＢｉ−Ｔｅ系、Ｐｂ−Ｔｅ系などの材料を用いる。 The thermoelectric conversion element which concerns on embodiment of this invention can be manufactured using the thermoelectric material obtained using the above methods. At this time, the thermoelectric conversion element can be manufactured using either one or both of the n-type and the p-type among the thermoelectric materials according to the embodiment of the present invention. When the thermoelectric material according to the embodiment of the present invention is used for only one of the n-type and the p-type, a material such as Bi—Te system or Pb—Te system is used for the other.
図１に本発明の実施形態に係る熱電変換素子の一例の断面図を示す。この熱電変換素子は、複数のｐ型熱電材料１とｎ型熱電材料２とを交互に配置し、下側の絶縁基板４ａ上の電極３ａおよび上側の絶縁基板４ｂ上の電極３ｂによって直列に接続した構造を有する。
FIG. 1 shows a cross-sectional view of an example of a thermoelectric conversion element according to an embodiment of the present invention. In this thermoelectric conversion element, a plurality of p-type
図１に示した熱電変換素子の原理を説明する。例えば、下側の絶縁基板４ａを高温に、上側の絶縁基板４ｂを低温にするように温度差を与えると、ｐ型熱電材料１の内部では正の電荷を持ったホールが低温側（上側）に移動し、ｎ型熱電材料２の内部では負の電荷を持った電子６が低温側（上側）に移動する結果、電位差が生じる。
The principle of the thermoelectric conversion element shown in FIG. 1 will be described. For example, when a temperature difference is given so that the lower insulating
以下、本発明の実施例を詳細に説明する。
（実施例１−１〜７および比較例１−１〜４）
代表的な実施例として表１に示す実施例１−２について説明する。原料として純度９９．９％のＴｉ、純度９９．９％のＺｒ、純度９９．９％のＨｆ、純度９９．９９％のＮｉ、および純度９９．９９％のＳｎを用意し、（Ｔｉ0.3Ｚｒ0.35Ｈｆ0.35）ＮｉＳｎで表される合金を得るように各原料を秤量した。秤量した原料を混合し、アーク炉内の水冷銅製ハースに装填して、２×１０-3Ｐａの真空度まで真空引きした。その後、純度９９．９９９％の高純度Ａｒを−０．０４ＭＰａまで導入して減圧Ａｒ雰囲気として、アーク溶解した。溶解後、水冷銅製ハースで急冷して金属塊を得た。この金属塊を石英管に１０-4Ｐａ以下の高真空で真空封入し、１１５０℃で２時間熱処理した。この金属塊を４５μｍ以下に粉砕した。得られた合金粉末を内径２０ｍｍの金型を用いて圧力５０ＭＰａで成形した。得られた成形体を内径２０ｍｍのカーボン製モールドに充填し、Ａｒ雰囲気中、３０ＭＰａ、１０３０℃で１時間加圧焼結して、直径約２０ｍｍ円盤状の焼結体を得た。
Hereinafter, embodiments of the present invention will be described in detail.
(Examples 1-1 to 7 and Comparative Examples 1-1 to 4)
Example 1-2 shown in Table 1 will be described as a typical example. As raw materials, Ti having a purity of 99.9%, Zr having a purity of 99.9%, Hf having a purity of 99.9%, Ni having a purity of 99.99%, and Sn having a purity of 99.99% were prepared, and (Ti 0.3 Zr Each raw material was weighed so as to obtain an alloy represented by 0.35 Hf 0.35 ) NiSn. The weighed raw materials were mixed, loaded into a water-cooled copper hearth in an arc furnace, and evacuated to a vacuum degree of 2 × 10 −3 Pa. Thereafter, high-purity Ar having a purity of 99.999% was introduced to −0.04 MPa to form a reduced pressure Ar atmosphere, and arc melting was performed. After dissolution, it was quenched with water-cooled copper hearth to obtain a metal lump. This metal block was vacuum-sealed in a quartz tube at a high vacuum of 10 −4 Pa or less and heat-treated at 1150 ° C. for 2 hours. This metal lump was pulverized to 45 μm or less. The obtained alloy powder was molded at a pressure of 50 MPa using a mold having an inner diameter of 20 mm. The obtained molded body was filled in a carbon mold having an inner diameter of 20 mm, and pressure sintered at 30 MPa and 1030 ° C. for 1 hour in an Ar atmosphere to obtain a disk-shaped sintered body having a diameter of about 20 mm.
マイクロメーターを用いてこの焼結体の外径と厚さを測定し、焼結体の体積を求めた。焼結体の重量と体積から焼結体の密度を調べたところ、７．４９ｇ／ｃｍ3であった。溶解後の合金の重量と体積から真密度を求めておいた。その結果、本実施例の焼結体は真密度の８８.０％の密度を有することがわかった。 The outer diameter and thickness of the sintered body were measured using a micrometer, and the volume of the sintered body was determined. When the density of the sintered compact was examined from the weight and volume of the sintered compact, it was 7.49 g / cm 3 . The true density was determined from the weight and volume of the alloy after melting. As a result, it was found that the sintered body of this example had a density of 88.0% of the true density.
この焼結体を粉末Ｘ線回折法によって調べたところ、ＭｇＡｇＡｓ型結晶相を主としていることが確認された。この焼結体の組成をＩＣＰ発光分光法で分析したところ、ほぼ所定の組成であることが確認された。 When this sintered body was examined by a powder X-ray diffraction method, it was confirmed that it was mainly composed of an MgAgAs type crystal phase. When the composition of the sintered body was analyzed by ICP emission spectroscopy, it was confirmed that the sintered body had a substantially predetermined composition.
得られた焼結体について、以下の方法によって熱電特性を評価した。
（ａ）抵抗率
焼結体から１．５ｍｍ×０．５ｍｍ×１８ｍｍの試料を切り出し、電極を形成し直流４端子法で測定した。
About the obtained sintered compact, the thermoelectric characteristic was evaluated with the following method.
(A) Resistivity A 1.5 mm × 0.5 mm × 18 mm sample was cut out from the sintered body, an electrode was formed, and measured by a direct current four-terminal method.
（ｂ）ゼーベック係数
焼結体から５ｍｍ×１．５ｍｍ×０．５ｍｍの試料を切り出し、その両端に２℃の温度差を付け起電力を測定し、ゼーベック係数を求めた。
(B) Seebeck coefficient A sample of 5 mm × 1.5 mm × 0.5 mm was cut out from the sintered body, a temperature difference of 2 ° C. was applied to both ends thereof, the electromotive force was measured, and the Seebeck coefficient was obtained.
（ｃ）熱伝導率
焼結体から外径１０ｍｍ×厚さ２．０ｍｍの試料を切り出し、レーザーフラッシュ法により熱拡散率を測定した。これとは別にＤＳＣ測定により比熱を求めた。また、上記で求めた焼結体の密度を用いた。これらの値から熱伝導率（格子熱伝導率）を算出した。
(C) Thermal conductivity A sample having an outer diameter of 10 mm and a thickness of 2.0 mm was cut out from the sintered body, and the thermal diffusivity was measured by a laser flash method. Separately, specific heat was determined by DSC measurement. Further, the density of the sintered body obtained above was used. Thermal conductivity (lattice thermal conductivity) was calculated from these values.
こうして得られた抵抗率、ゼーベック係数および熱伝導率の値を用い、前述の式（１）により無次元性能指数ＺＴを求めた。３００Ｋおよび７００Ｋにおける抵抗率、ゼーベック係数、熱伝導率および無次元性能指数は以下のとおりであった。 Using the resistivity, Seebeck coefficient, and thermal conductivity values thus obtained, the dimensionless figure of merit ZT was determined by the above-described equation (1). The resistivity, Seebeck coefficient, thermal conductivity, and dimensionless figure of merit at 300K and 700K were as follows.
３００Ｋ：抵抗率１．０３×１０-2Ωｃｍ
ゼーベック係数−３６４μＶ／Ｋ
熱伝導率２．４Ｗ／ｍＫ
ＺＴ＝０．１６
７００Ｋ：抵抗率３．１０×１０-3Ωｃｍ
ゼーベック係数−３６８μＶ／Ｋ
熱伝導率２．０Ｗ／ｍＫ
ＺＴ＝１．５４
一方、代表的な比較例として表１に示す比較例１−１について説明する。実施例１−２と全く同様に、原料の秤量、アーク溶解、熱処理、粉砕、成形を行った。得られた成形体を内径２０ｍｍのカーボン製モールドに充填し、Ａｒ雰囲気中、８０ＭＰａ、１２００℃で１時間加圧焼結して、直径約２０ｍｍ円盤状の焼結体を得た。この焼結体はほぼ空隙を含まないとみなせるものであった。マイクロメーターを用いてこの焼結体の外径と厚さを測定し、焼結体の体積を求めた。その結果、本比較例の焼結体は真密度の９９．９％の密度であり、ほぼ真密度を持つ焼結体が得られていることがわかった。
300K: Resistivity 1.03 × 10 -2 Ωcm
Seebeck coefficient -364μV / K
Thermal conductivity 2.4W / mK
ZT = 0.16
700K: Resistivity 3.10 × 10 −3 Ωcm
Seebeck coefficient -368μV / K
Thermal conductivity 2.0W / mK
ZT = 1.54
On the other hand, Comparative Example 1-1 shown in Table 1 will be described as a representative comparative example. In exactly the same manner as in Example 1-2, weighing of raw materials, arc melting, heat treatment, pulverization, and molding were performed. The obtained molded body was filled in a carbon mold having an inner diameter of 20 mm and pressure sintered at 80 MPa and 1200 ° C. for 1 hour in an Ar atmosphere to obtain a disk-shaped sintered body having a diameter of about 20 mm. This sintered body could be regarded as substantially free of voids. The outer diameter and thickness of the sintered body were measured using a micrometer, and the volume of the sintered body was determined. As a result, it was found that the sintered body of this comparative example had a density of 99.9% of the true density, and a sintered body having a substantially true density was obtained.
得られた焼結体について、上記と同様の方法によって熱電特性を評価した。３００Ｋおよび７００Ｋにおける抵抗率、ゼーベック係数、熱伝導率および無次元性能指数は以下のとおりであった。 About the obtained sintered compact, the thermoelectric characteristic was evaluated by the method similar to the above. The resistivity, Seebeck coefficient, thermal conductivity, and dimensionless figure of merit at 300K and 700K were as follows.
３００Ｋ：抵抗率８．６２×１０-3Ωｃｍ
ゼーベック係数−３３３μＶ／Ｋ
熱伝導率３．２Ｗ／ｍＫ
ＺＴ＝０．１２
７００Ｋ：抵抗率２．３５×１０-3Ωｃｍ
ゼーベック係数−３２３μＶ／Ｋ
熱伝導率２．６Ｗ／ｍＫ
ＺＴ＝１．２０
表１には、密度（ｄ）／真密度（ｄ0）のパーセンテージ［（ｄ／ｄ0）×１００］、熱伝導率κ、出力因子Ｐｆ、無次元性能指数ＺＴを示す。
300K: Resistivity 8.62 × 10 −3 Ωcm
Seebeck coefficient -333μV / K
Thermal conductivity 3.2W / mK
ZT = 0.12
700K: resistivity 2.35 × 10 −3 Ωcm
Seebeck coefficient -323μV / K
Thermal conductivity 2.6W / mK
ZT = 1.20
Table 1 shows density (d) / true density (d 0 ) percentage [(d / d 0 ) × 100], thermal conductivity κ, output factor Pf, and dimensionless figure of merit ZT.
実施例１−２と比較例１−１との対比からわかるように、（Ｔｉ0.3Ｚｒ0.35Ｈｆ0.35）ＮｉＳｎの組成で密度を真密度の８８.０％にすることにより、熱伝導率を低下させることができ、高性能の熱電材料が得られた。 As can be seen from the comparison between Example 1-2 and Comparative Example 1-1, the thermal conductivity is lowered by setting the density to 88.0% of the true density with the composition of (Ti 0.3 Zr 0.35 Hf 0.35 ) NiSn. And a high-performance thermoelectric material was obtained.
その他の実施例および比較例について説明する。
焼結条件を、Ａｒ雰囲気中、３０ＭＰａ、９５０℃、１時間とした以外は実施例１−２と全く同様にして焼結体を得た。この焼結体は真密度の８２.２％の密度を有していた（実施例１−１）。焼結条件を、Ａｒ雰囲気中、３０ＭＰａ、１１３０℃、１時間とした以外は実施例１−２と全く同様にして焼結体を得た。この焼結体は真密度の９５.３％の密度を有していた（実施例１−３）。焼結条件を、Ａｒ雰囲気中、３０ＭＰａ、７８０℃、１時間とした以外は実施例１−２と全く同様にして焼結体を得た。この焼結体は真密度の６９.１％の密度を有していた（比較例１−２）。
Other examples and comparative examples will be described.
A sintered body was obtained in exactly the same manner as in Example 1-2 except that the sintering conditions were 30 MPa, 950 ° C., and 1 hour in an Ar atmosphere. This sintered body had a density of 82.2% of the true density (Example 1-1). A sintered body was obtained in exactly the same manner as in Example 1-2 except that the sintering conditions were set to 30 MPa, 1130 ° C., and 1 hour in an Ar atmosphere. This sintered body had a density of 95.3% of the true density (Example 1-3). A sintered body was obtained in the same manner as in Example 1-2 except that the sintering conditions were set to 30 MPa, 780 ° C., and 1 hour in an Ar atmosphere. This sintered body had a density of 69.1% of the true density (Comparative Example 1-2).
図２に（Ｔｉ0.3Ｚｒ0.35Ｈｆ0.35）ＮｉＳｎについて焼結温度と密度／真密度のパーセンテージとの関係を示す。図３に（Ｔｉ0.3Ｚｒ0.35Ｈｆ0.35）ＮｉＳｎについて密度／真密度のパーセンテージと熱伝導率（格子熱伝導率）との関係を示す。図３から、密度の低い試料は熱伝導率が低下することがわかる。 FIG. 2 shows the relationship between sintering temperature and density / percentage of true density for (Ti 0.3 Zr 0.35 Hf 0.35 ) NiSn. FIG. 3 shows the relationship between the percentage of density / true density and thermal conductivity (lattice thermal conductivity) for (Ti 0.3 Zr 0.35 Hf 0.35 ) NiSn. From FIG. 3, it can be seen that the thermal conductivity of the low density sample decreases.
次に、（Ｔｉ0.3Ｚｒ0.35Ｈｆ0.35）ＮｉＳｎ0.994Ｓｂ0.006で表される合金を得るように各原料を秤量し、アーク溶解、熱処理、粉砕、成形を行った。得られた成形体を内径２０ｍｍのカーボン製モールドに充填し、加圧焼結して、直径約２０ｍｍ円盤状の焼結体を得た。このとき、下記のように焼結条件を変えることにより、種々の密度を有する焼結体を得た。 Next, each raw material was weighed so as to obtain an alloy represented by (Ti 0.3 Zr 0.35 Hf 0.35 ) NiSn 0.994 Sb 0.006 , and arc melting, heat treatment, pulverization and molding were performed. The obtained molded body was filled in a carbon mold having an inner diameter of 20 mm, and pressure-sintered to obtain a disk-shaped sintered body having a diameter of about 20 mm. At this time, sintered bodies having various densities were obtained by changing the sintering conditions as described below.
焼結条件を、Ａｒ雰囲気中、３０ＭＰａ、９５０℃、１時間とすることにより、真密度の８１.８％の密度を有する焼結体を得た（実施例１−４）。焼結条件を、Ａｒ雰囲気中、３０ＭＰａ、１０３０℃、１時間とすることにより、真密度の８８.０％の密度を有する焼結体を得た（実施例１−５）。焼結条件を、Ａｒ雰囲気中、３０ＭＰａ、１１３０℃、１時間とすることにより、真密度の９５.１％の密度を有する焼結体を得た（実施例１−６）。 By setting the sintering conditions to 30 MPa, 950 ° C., and 1 hour in an Ar atmosphere, a sintered body having a density of 81.8% of the true density was obtained (Example 1-4). By setting the sintering conditions to 30 MPa, 1030 ° C., and 1 hour in an Ar atmosphere, a sintered body having a density of 88.0% of the true density was obtained (Example 1-5). By setting the sintering conditions to 30 MPa, 1130 ° C., and 1 hour in an Ar atmosphere, a sintered body having a density of 95.1% of the true density was obtained (Example 1-6).
また、ＺｒＮｉＳｎで表される合金を得るように各原料を秤量し、アーク溶解、熱処理、粉砕、成形を行った。得られた成形体を内径２０ｍｍのカーボン製モールドに充填し、Ａｒ雰囲気中、８０ＭＰａ、１２００℃、１時間の条件で加圧焼結して、直径約２０ｍｍ円盤状の焼結体を得た。この焼結体は空隙を含まないとみなせるものであり、真密度の９９.９％の密度を有していた（比較例１−３）。 Moreover, each raw material was weighed so as to obtain an alloy represented by ZrNiSn, and arc melting, heat treatment, pulverization, and molding were performed. The obtained molded body was filled in a carbon mold having an inner diameter of 20 mm, and pressure-sintered in an Ar atmosphere at 80 MPa, 1200 ° C. for 1 hour to obtain a disk-shaped sintered body having a diameter of about 20 mm. This sintered body can be regarded as not containing voids, and had a density of 99.9% of the true density (Comparative Example 1-3).
これまでに説明した熱電材料はいずれもｎ型のものである。そこで、ｐ型熱電材料についても検討した。組成式（Ａ）におけるαとしてＣｏ、βとしてＳｂおよびＳｎをそれぞれ用い、（Ｔｉ0.3Ｚｒ0.35Ｈｆ0.35）ＣｏＳｂ0.85Ｓｎ0.15で表される合金を得るように各原料を秤量し、アーク溶解、熱処理、粉砕、成形を行った。得られた成形体を内径２０ｍｍのカーボン製モールドに充填し、Ａｒ雰囲気中、３０ＭＰａ、１０５０℃、１時間の条件で加圧焼結して、直径約２０ｍｍ円盤状の焼結体を得た。この焼結体の密度は真密度の８６.７％であった（実施例１−７）。一方、焼結条件をＡｒ雰囲気中、８０ＭＰａ、１３００℃、１時間とした以外は実施例１−７と全く同様にして焼結体を得た。この焼結体は空隙を含まないとみなせるものであり、真密度の９９.８％の密度を有していた（比較例１−４）。 All the thermoelectric materials described so far are n-type. Therefore, a p-type thermoelectric material was also examined. In the composition formula (A), Co is used as α, Sb and Sn are used as β, each raw material is weighed to obtain an alloy represented by (Ti 0.3 Zr 0.35 Hf 0.35 ) CoSb 0.85 Sn 0.15 , arc melting, and heat treatment Then, pulverization and molding were performed. The obtained molded body was filled in a carbon mold having an inner diameter of 20 mm and pressure-sintered in an Ar atmosphere at 30 MPa and 1050 ° C. for 1 hour to obtain a disk-shaped sintered body having a diameter of about 20 mm. The density of this sintered body was 86.7% of the true density (Example 1-7). On the other hand, a sintered body was obtained in exactly the same manner as in Example 1-7, except that the sintering conditions were 80 MPa, 1300 ° C., and 1 hour in an Ar atmosphere. This sintered body can be regarded as not containing voids, and had a density of 99.8% of the true density (Comparative Example 1-4).
前記と同様に、それぞれの試料について、３００Ｋおよび７００Ｋにおける熱電特性を評価し、得られた結果を下記表１にまとめて示す。 Similarly to the above, the thermoelectric characteristics at 300K and 700K were evaluated for each sample, and the obtained results are summarized in Table 1 below.
表１からわかるように、密度が真密度の７０.０〜９９.０％であるＭｇＡｇＡｓ型結晶相を有する熱電材料はいずれも、密度が真密度の９９.０％より大または７０.０％より小であるもの（比較例１−１〜４）と対比して、高い無次元性能指数ＺＴを示している。
（実施例２〜５）
以下の実施例では、実施例１において取り扱った熱電材料の構成元素の一部を他の元素で置換した熱電材料について説明する。
(Examples 2 to 5)
In the following examples, a thermoelectric material in which some of the constituent elements of the thermoelectric material handled in Example 1 are replaced with other elements will be described.
ここで、実施例１で取り扱った熱電材料を下記組成式（Ａ’）
（Ｔｉ0.3Ｚｒ0.35Ｈｆ0.35）αβ …（Ａ’）
（αはＮｉおよびＣｏから選択される少なくとも一種の元素、βはＳｎおよびＳｂから選択される少なくとも一種の元素である）
で表す。
Here, the thermoelectric material handled in Example 1 is represented by the following composition formula (A ′)
(Ti 0.3 Zr 0.35 Hf 0.35 ) αβ (A ′)
(Α is at least one element selected from Ni and Co, β is at least one element selected from Sn and Sb)
Represented by
実施例２
上記組成式（Ａ’）における元素Ｍ（Ｔｉ，ＺｒおよびＨｆ）の一部をＥｒで置換して（Ｅｒ0.1（Ｔｉ0.3Ｚｒ0.35Ｈｆ0.35）0.9）ＮｉＳｎで表される合金を得るように各原料を秤量し、アーク溶解、熱処理、粉砕、成形を行い、得られた成形体を焼結して密度が真密度の８６.８％である焼結体を作製した。この試料について、３００Ｋおよび７００Ｋにおける熱電特性を評価し、得られた結果を下記表２に示す。表２に示されるように、この熱電材料は良好な熱電特性を有している。
Part of the element M (Ti, Zr and Hf) in the composition formula (A ′) is substituted with Er (Er 0.1 (Ti 0.3 Zr 0.35 Hf 0.35 ) 0.9 ) to obtain an alloy represented by NiSn. The raw materials were weighed and subjected to arc melting, heat treatment, pulverization, and molding, and the resulting molded body was sintered to produce a sintered body having a density of 86.8% of the true density. The sample was evaluated for thermoelectric properties at 300K and 700K, and the results obtained are shown in Table 2 below. As shown in Table 2, this thermoelectric material has good thermoelectric properties.
また、組成式（Ａ’）における元素Ｍ（Ｔｉ，Ｚｒ，Ｈｆ）の一部をＥｒ以外の元素Ｌｎ（Ｙおよび希土類元素からなる群より選択される少なくとも一種の元素）で置換した熱電材料も良好な熱電特性を有することが確認された。 A thermoelectric material in which a part of the element M (Ti, Zr, Hf) in the composition formula (A ′) is replaced with an element Ln other than Er (at least one element selected from the group consisting of Y and rare earth elements) is also provided. It was confirmed to have good thermoelectric properties.
実施例３
上記組成式（Ａ’）における元素Ｍ（Ｔｉ，ＺｒおよびＨｆ）の一部をＶで置換して（Ｖ0.01（Ｔｉ0.3Ｚｒ0.35Ｈｆ0.35）0.99）ＮｉＳｎで表わされる合金を得るように各原料を秤量し、アーク溶解、熱処理、粉砕、成形を行い、得られた成形体を焼結して密度が真密度の８７.０％である焼結体を作製した。この試料について、３００Ｋおよび７００Ｋにおける熱電特性を評価し、得られた結果を下記表３に示す。表３に示されるように、この熱電材料は良好な熱電特性を有している。
Each raw material is obtained by substituting a part of the element M (Ti, Zr and Hf) in the composition formula (A ′) with V (V 0.01 (Ti 0.3 Zr 0.35 Hf 0.35 ) 0.99 ) to obtain an alloy represented by NiSn. Were weighed and subjected to arc melting, heat treatment, pulverization, and molding, and the resulting molded body was sintered to produce a sintered body having a density of 87.0% of the true density. The sample was evaluated for thermoelectric properties at 300K and 700K, and the results obtained are shown in Table 3 below. As shown in Table 3, this thermoelectric material has good thermoelectric properties.
また、組成式（Ａ’）における元素Ｍ（Ｔｉ，ＺｒおよびＨｆ）の一部をＶ以外の元素Ｍ’（Ｎｂ，Ｔａ、Ｃｒ、ＭｏおよびＴａからなる群より選択される少なくとも一種の元素）で置換した熱電材料も良好な熱電特性を有することが確認された。 Further, a part of the element M (Ti, Zr and Hf) in the composition formula (A ′) is an element M ′ other than V (at least one element selected from the group consisting of Nb, Ta, Cr, Mo and Ta). It was confirmed that the thermoelectric material substituted with 1 also has good thermoelectric properties.
実施例４
上記組成式（Ａ’）における元素α（Ｎｉ）の一部をＣｕで置換して（Ｔｉ0.3Ｚｒ0.35Ｈｆ0.35）Ｎｉ0.99Ｃｕ0.01Ｓｎで表される合金を得るように各原料を秤量し、アーク溶解、熱処理、粉砕、成形を行い、得られた成形体を焼結して密度が真密度の８６.９％である焼結体を作製した。この試料について、３００Ｋおよび７００Ｋにおける熱電特性を評価し、得られた結果を下記表４に示す。表４に示されるように、この熱電材料は良好な熱電特性を有している。
Each raw material is weighed so as to obtain an alloy represented by (Ti 0.3 Zr 0.35 Hf 0.35 ) Ni 0.99 Cu 0.01 Sn by replacing a part of the element α (Ni) in the composition formula (A ′) with Cu, Arc melting, heat treatment, pulverization, and molding were performed, and the obtained molded body was sintered to produce a sintered body having a density of 86.9% of the true density. The sample was evaluated for thermoelectric properties at 300K and 700K, and the results obtained are shown in Table 4 below. As shown in Table 4, this thermoelectric material has good thermoelectric properties.
また、組成式（Ａ’）における元素α（Ｎｉ）の一部をＣｕ以外の元素α’（ＭｎおよびＦｅから選択される少なくとも一種の元素）で置換した熱電材料も良好な熱電特性を有することが確認された。 A thermoelectric material in which a part of the element α (Ni) in the composition formula (A ′) is replaced with an element α ′ other than Cu (at least one element selected from Mn and Fe) also has good thermoelectric properties. Was confirmed.
実施例５
上記組成式（Ａ’）における元素β（Ｓｎ）の一部をＧｅで置換して（Ｔｉ0.3Ｚｒ0.35Ｈｆ0.35）ＮｉＳｎ0.994Ｇｅ0.006で表される合金を得るように各原料を秤量し、アーク溶解、熱処理、粉砕、成形を行い、得られた成形体を焼結して密度が真密度の８７.０％である焼結体を作製した。この試料について、３００Ｋおよび７００Ｋにおける熱電特性を評価し、得られた結果を下記表５に示す。表５に示されるように、この熱電材料は良好な熱電特性を有している。
A part of the element β (Sn) in the composition formula (A ′) is replaced with Ge, and each raw material is weighed so as to obtain an alloy represented by (Ti 0.3 Zr 0.35 Hf 0.35 ) NiSn 0.994 Ge 0.006. Dissolution, heat treatment, pulverization, and molding were performed, and the resulting molded body was sintered to produce a sintered body having a density of 87.0% of the true density. The sample was evaluated for thermoelectric properties at 300K and 700K, and the results obtained are shown in Table 5 below. As shown in Table 5, this thermoelectric material has good thermoelectric properties.
また、組成式（Ａ’）における元素β（Ｓｎ）の一部をＧｅ以外の元素β’（Ｓｉ，Ｍｇ，Ａｓ，Ｂｉ，Ｐｂ，ＧａおよびＩｎからなる群より選択される少なくとも一種の元素）で置換した熱電材料も良好な熱電特性を有することが確認された。 Further, a part of the element β (Sn) in the composition formula (A ′) is an element β ′ other than Ge (at least one element selected from the group consisting of Si, Mg, As, Bi, Pb, Ga, and In). It was confirmed that the thermoelectric material substituted with 1 also has good thermoelectric properties.
１…ｐ型熱電材料、２…ｎ型熱電材料、３ａ、３ｂ…電極、４ａ、４ｂ…絶縁基板、５…ホール、６…電子。 1 ... p-type thermoelectric material, 2 ... n-type thermoelectric material, 3a, 3b ... electrode, 4a, 4b ... insulating substrate, 5 ... hole, 6 ... electron.
Claims (8)
（Ｔｉa1Ｚｒb1Ｈｆc1）xαyβ100-x-y
（ここで、０＜a1≦１、０＜b1≦１、０＜c1≦１、a1＋b1＋c1＝１、３０≦ｘ≦３５、３０≦ｙ≦３５、αはＮｉ、βはＳｎであり、βの３０原子％以下がＳｉ，Ｍｇ，Ａｓ，Ｓｂ，Ｂｉ，Ｇｅ，Ｐｂ，ＧａおよびＩｎからなる群より選択される少なくとも一種の元素で置換されている）
で表わされ、ＭｇＡｇＡｓ型結晶相を主相とし、密度が真密度の８１．８〜９９．０％である焼結体からなることを特徴とする熱電材料。 The following composition formula (Ti a1 Zr b1 Hf c1 ) x α y β 100-xy
(Where 0 <a1 ≦ 1, 0 <b1 ≦ 1, 0 <c1 ≦ 1, a1 + b1 + c1 = 1, 30 ≦ x ≦ 35, 30 ≦ y ≦ 35, α is Ni , β is Sn , and β 30 atomic percent or less is substituted with at least one element selected from the group consisting of Si, Mg, As, Sb, Bi, Ge, Pb, Ga and In)
A thermoelectric material comprising a sintered body having a MgAgAs crystal phase as a main phase and a density of 81.8 to 99.0% of the true density.
（Ｔｉ a1 Ｚｒ b1 Ｈｆ c1 ） x α y β 100-x-y
（ここで、０＜a1≦１、０＜b1≦１、０＜c1≦１、a1＋b1＋c1＝１、３０≦ｘ≦３５、３０≦ｙ≦３５、αはＣｏ、βはＳｂであり、βの３０原子％以下がＳｎ,Ｓｉ，Ｍｇ，Ａｓ，Ｂｉ，Ｇｅ，Ｐｂ，ＧａおよびＩｎからなる群より選択される少なくとも一種の元素で置換されている）
で表わされ、ＭｇＡｇＡｓ型結晶相を主相とし、密度が真密度の８１．８〜９９．０％である焼結体からなることを特徴とする熱電材料。 The following composition formula
(Ti a1 Zr b1 Hf c1 ) x α y β 100-xy
(Where 0 <a1 ≦ 1, 0 <b1 ≦ 1, 0 <c1 ≦ 1, a1 + b1 + c1 = 1, 30 ≦ x ≦ 35, 30 ≦ y ≦ 35, α is Co, β is Sb, 30 atomic% or less is substituted with at least one element selected from the group consisting of Sn, Si, Mg, As, Bi, Ge, Pb, Ga and In)
A thermoelectric material comprising a sintered body having a MgAgAs crystal phase as a main phase and a density of 81.8 to 99.0% of the true density .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2004100812A JP4497981B2 (en) | 2004-03-30 | 2004-03-30 | Thermoelectric material and thermoelectric conversion element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2004100812A JP4497981B2 (en) | 2004-03-30 | 2004-03-30 | Thermoelectric material and thermoelectric conversion element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2005286228A JP2005286228A (en) | 2005-10-13 |
| JP4497981B2 true JP4497981B2 (en) | 2010-07-07 |
Family
ID=35184235
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2004100812A Expired - Lifetime JP4497981B2 (en) | 2004-03-30 | 2004-03-30 | Thermoelectric material and thermoelectric conversion element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4497981B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11957052B2 (en) | 2016-07-28 | 2024-04-09 | Kabushiki Kaisha Toshiba | Thermoelectric material, manufacturing method of thermoelectric material, thermoelectric conversion element, and thermoelectric conversion module |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007158191A (en) * | 2005-12-07 | 2007-06-21 | Toshiba Corp | Thermoelectric material, and thermoelectric conversion element using same |
| JP4762083B2 (en) * | 2006-08-25 | 2011-08-31 | 株式会社東芝 | Thermoelectric conversion material and thermoelectric conversion module using the same |
| JP2008227321A (en) * | 2007-03-15 | 2008-09-25 | Toshiba Corp | Thermoelectric conversion material and thermoelectric conversion module using the same |
| JP5333001B2 (en) | 2008-12-15 | 2013-11-06 | 株式会社豊田中央研究所 | Thermoelectric material and manufacturing method thereof |
| JP5877274B2 (en) * | 2013-04-05 | 2016-03-02 | パナソニック株式会社 | Thermoelectric conversion material |
| JP5877275B2 (en) * | 2013-04-10 | 2016-03-02 | パナソニック株式会社 | Method for producing thermoelectric conversion material |
| JP5820550B2 (en) * | 2013-07-22 | 2015-11-24 | パナソニック株式会社 | (Zr, Hf) 3Ni3Sb4 n-type thermoelectric conversion material |
| CN104681706B (en) * | 2015-02-12 | 2017-11-17 | 浙江大学 | P-type FeNbHfSb thermoelectric materials of the high figure of merit and preparation method thereof |
| PL3196951T4 (en) * | 2016-01-21 | 2019-07-31 | Evonik Degussa Gmbh | Rational method for the powder metallurgical production of thermoelectric components |
| CN112349827A (en) * | 2020-11-06 | 2021-02-09 | 哈尔滨工业大学（深圳） | Wearable body temperature power generation module for continuous energy supply and preparation method |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004049464A1 (en) * | 2002-11-28 | 2004-06-10 | Sumitomo Electric Industries, Ltd. | Thermoelectric material and method for producing same |
-
2004
- 2004-03-30 JP JP2004100812A patent/JP4497981B2/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004049464A1 (en) * | 2002-11-28 | 2004-06-10 | Sumitomo Electric Industries, Ltd. | Thermoelectric material and method for producing same |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11957052B2 (en) | 2016-07-28 | 2024-04-09 | Kabushiki Kaisha Toshiba | Thermoelectric material, manufacturing method of thermoelectric material, thermoelectric conversion element, and thermoelectric conversion module |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2005286228A (en) | 2005-10-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2007158191A (en) | Thermoelectric material, and thermoelectric conversion element using same | |
| EP1523048B1 (en) | Thermoelectric material and thermoelectric module using the thermoelectric material | |
| JP4745183B2 (en) | Thermoelectric conversion material and thermoelectric conversion module using the same | |
| JP4468044B2 (en) | Thermoelectric material and thermoelectric conversion element | |
| US20070125416A1 (en) | Thermoelectric material and thermoelectric conversion device using same | |
| JP2004356607A (en) | Thermoelectric conversion material and thermoelectric transducer | |
| JP4762083B2 (en) | Thermoelectric conversion material and thermoelectric conversion module using the same | |
| US10008653B2 (en) | NbFeSb based half-heusler thermoelectric materials and methods of fabrication and use | |
| JP5099976B2 (en) | Method for producing thermoelectric conversion material | |
| JP4497981B2 (en) | Thermoelectric material and thermoelectric conversion element | |
| JP6873105B2 (en) | Compounds, thermoelectric conversion materials and methods for producing compounds | |
| KR102399079B1 (en) | Half-heusler type thermoelectric material, method for manufacturing the same, thermoelectric element comprising the same | |
| JP6873104B2 (en) | Compounds and thermoelectric conversion materials | |
| JP5271054B2 (en) | Method for producing thermoelectric conversion material | |
| JP2003197985A (en) | Thermoelectric conversion material and thermoelectric conversion element using the same | |
| JP2007173799A (en) | Thermoelectric conversion material and thermoelectric conversion element | |
| JP5563024B2 (en) | Thermoelectric conversion material and thermoelectric conversion module using the same | |
| JP2007158192A (en) | Thermoelectric conversion material, and thermoelectric conversion element using same | |
| JP3923041B2 (en) | Thermoelectric conversion material and thermoelectric conversion element using the same | |
| JP4481704B2 (en) | Thermoelectric conversion material and thermoelectric conversion element using the same | |
| JP2008227321A (en) | Thermoelectric conversion material and thermoelectric conversion module using the same | |
| JP4521215B2 (en) | Thermoelectric conversion material and thermoelectric conversion element | |
| WO2014162726A1 (en) | Thermoelectric conversion material | |
| CN113272978B (en) | Silicide alloy material and thermoelectric conversion element using same | |
| JP2006019754A (en) | Thermoelectric conversion material and thermoelectric conversion element using the same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20070118 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20090901 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20090903 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20091030 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20091215 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20100212 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20100323 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20100413 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130423 Year of fee payment: 3 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 4497981 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140423 Year of fee payment: 4 |
|
| EXPY | Cancellation because of completion of term |