JP5274146B2 - Thermoelectric semiconductor comprising magnesium, silicon and tin and method for producing the same - Google Patents
Thermoelectric semiconductor comprising magnesium, silicon and tin and method for producing the same Download PDFInfo
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- JP5274146B2 JP5274146B2 JP2008205583A JP2008205583A JP5274146B2 JP 5274146 B2 JP5274146 B2 JP 5274146B2 JP 2008205583 A JP2008205583 A JP 2008205583A JP 2008205583 A JP2008205583 A JP 2008205583A JP 5274146 B2 JP5274146 B2 JP 5274146B2
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- 239000011135 tin Substances 0.000 title claims description 44
- 239000004065 semiconductor Substances 0.000 title claims description 40
- 239000011777 magnesium Substances 0.000 title claims description 30
- 229910052710 silicon Inorganic materials 0.000 title claims description 20
- 229910052718 tin Inorganic materials 0.000 title claims description 20
- 229910052749 magnesium Inorganic materials 0.000 title claims description 19
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 title claims description 17
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims description 17
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 title claims description 17
- 239000010703 silicon Substances 0.000 title claims description 17
- 238000004519 manufacturing process Methods 0.000 title claims description 9
- 239000002019 doping agent Substances 0.000 claims description 32
- 239000000203 mixture Substances 0.000 claims description 20
- 239000000126 substance Substances 0.000 claims description 12
- 239000010949 copper Substances 0.000 claims description 11
- 239000010931 gold Substances 0.000 claims description 11
- 229910052783 alkali metal Inorganic materials 0.000 claims description 10
- 150000001340 alkali metals Chemical class 0.000 claims description 10
- 229910052751 metal Inorganic materials 0.000 claims description 10
- 238000005245 sintering Methods 0.000 claims description 10
- 239000002184 metal Substances 0.000 claims description 9
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 8
- 239000002994 raw material Substances 0.000 claims description 8
- 229910052709 silver Inorganic materials 0.000 claims description 8
- 239000004332 silver Substances 0.000 claims description 8
- 229910052802 copper Inorganic materials 0.000 claims description 6
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 6
- 229910052737 gold Inorganic materials 0.000 claims description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 5
- 238000003746 solid phase reaction Methods 0.000 claims description 5
- 150000007942 carboxylates Chemical class 0.000 claims description 4
- 229910000765 intermetallic Inorganic materials 0.000 description 11
- 238000000034 method Methods 0.000 description 8
- 150000003839 salts Chemical class 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 238000003786 synthesis reaction Methods 0.000 description 6
- 229910019018 Mg 2 Si Inorganic materials 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 229910052792 caesium Inorganic materials 0.000 description 3
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910008355 Si-Sn Inorganic materials 0.000 description 2
- 229910006453 Si—Sn Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005304 joining Methods 0.000 description 2
- HGPXWXLYXNVULB-UHFFFAOYSA-M lithium stearate Chemical compound [Li+].CCCCCCCCCCCCCCCCCC([O-])=O HGPXWXLYXNVULB-UHFFFAOYSA-M 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 235000021355 Stearic acid Nutrition 0.000 description 1
- YZCKVEUIGOORGS-NJFSPNSNSA-N Tritium Chemical compound [3H] YZCKVEUIGOORGS-NJFSPNSNSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 1
- ZOAIGCHJWKDIPJ-UHFFFAOYSA-M caesium acetate Chemical compound [Cs+].CC([O-])=O ZOAIGCHJWKDIPJ-UHFFFAOYSA-M 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- -1 copper metals Chemical class 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 1
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 1
- 239000010893 paper waste Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910052701 rubidium Inorganic materials 0.000 description 1
- IGLNJRXAVVLDKE-UHFFFAOYSA-N rubidium atom Chemical compound [Rb] IGLNJRXAVVLDKE-UHFFFAOYSA-N 0.000 description 1
- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000008117 stearic acid Substances 0.000 description 1
Images
Description
本発明は、マグネシウム、珪素、スズからなるｐ型の熱電半導体およびその製造方法の技術分野に属するものである。 The present invention belongs to the technical field of a p-type thermoelectric semiconductor made of magnesium, silicon, and tin and a method for manufacturing the same.
今日、マグネシウム（Ｍｇ）、珪素（Ｓｉ）、スズ（Ｓｎ）の金属からなる固溶体を焼結して製造した金属間化合物として、一般化学式
Ｍｇ２Ｓｉ１−ＺＳｎＺ
であらわされるものが知られている。そしてこの金属間化合物において、Ｚ＝０．４〜０．６の範囲のものが熱電特性に優れることが既に報告されている（特許文献１）。
ところが前記範囲の金属間化合物の焼結体の中には単相のものができていなかったが、短時間の焼結反応で安定した熱電半導体として利用できる単相の金属間化合物の焼結体を簡単に生成することが要求される。さらにはこれら金属間化合物の焼結体の熱電半導体としての特性がさらに向上することも要求されており、そこで、化学式、
Ｍｇ２Ｓｉ０．５Ｓｎ０．５
の焼結体にドーパントとしてアンチモン（Ｓｂ）やビスマス（Ｂｉ）を添加することでゼーべック係数αがマイナスになる良型の安定したｎ型の熱電半導体を得ることができることが報告されている（非特許文献１、特許文献２）。
What is represented is known. And in this intermetallic compound, the thing of the range of Z = 0.4-0.6 has already been reported that it is excellent in a thermoelectric characteristic (patent document 1).
However, among the sintered bodies of intermetallic compounds in the above range, single-phase sintered bodies were not made, but single-phase sintered bodies of intermetallic compounds that can be used as stable thermoelectric semiconductors in a short-time sintering reaction. Is required to be generated easily. Furthermore, it is required that the properties of these intermetallic compounds as a thermoelectric semiconductor be further improved.
Mg 2 Si 0.5 Sn 0.5
It has been reported that by adding antimony (Sb) or bismuth (Bi) as a dopant to the sintered body, a good and stable n-type thermoelectric semiconductor having a negative Seebeck coefficient α can be obtained. (Non-patent
ところが前記ドーパントを添加した半導体は、何れもｎ型であってｐ型ではなく、熱電素子化に向けてｐ型伝導を示す高性能なＭｇ−Ｓｉ−Ｓｎ系半導体材料の開発が望まれるが、化学量論組成でＭｇ２Ｓｉ０．５Ｓｎ０．５のものを単純にドーパントの添加によってｐ型化することは、高性能化ということを絡めた場合に困難である。
そこで本発明の発明者等は、一般化学式ＭｇＸＳｉ１−ＹＳｎＹで示される熱電半導体において、
１．９８≦Ｘ≦２．０１
０．７２≦Ｙ≦０．９５
の範囲のものが室温においてｐ型の熱電半導体になることを発見した（特願２００８−７２８３８号）。しかしながらこのものは、絶対温度４００Ｋ付近を超えるとｎ型になって安定性、実用性に欠けるという問題があり、ここに本発明が解決しようとする課題がある。
However, the semiconductors to which the dopant is added are all n-type and not p-type, and it is desired to develop a high-performance Mg-Si-Sn-based semiconductor material that exhibits p-type conduction toward the thermoelectric device. It is difficult to simply convert a stoichiometric composition of Mg 2 Si 0.5 Sn 0.5 into a p-type by adding a dopant in the case of high performance.
Therefore, the inventors of the present invention, in the thermoelectric semiconductor represented by the general chemical formula Mg X Si 1-Y Sn Y ,
1.98 ≦ X ≦ 2.01
0.72 ≦ Y ≦ 0.95
It has been found that those in the range become p-type thermoelectric semiconductors at room temperature (Japanese Patent Application No. 2008-72838). However, there is a problem that this product becomes n-type when the absolute temperature exceeds about 400K and lacks stability and practicality, and there is a problem to be solved by the present invention.
本発明は、上記の如き実情に鑑みこれらの課題を解決することを目的として創作されたものであって、請求項１の発明は、原料のマグネシウム、珪素、スズを液−固相反応せしめて一般化学式
ＭｇＸＳｉ１−ＹＳｎＹ
で示される熱電半導体を焼結して製造するにあたり、該熱電半導体はｐ型であって、焼結体組成が、
１．９８≦Ｘ≦２．０１
０．７２≦Ｙ≦０．９５
であり、ドーパントとして、１Ａ族のアルカリ金属、１Ｂ族の銅（Ｃｕ）、銀（Ａｇ）、金（Ａｕ）の少なくとも何れか一つの金属を添加して得ることを特徴とするマグネシウム、珪素、スズからなる熱電半導体の製造方法である。
請求項２の発明は、原料のマグネシウム、珪素、スズを液−固相反応せしめて一般化学式
ＭｇＸＳｉ１−ＹＳｎＹ
で示されるものを焼結して製造した熱電半導体において、該熱電半導体はｐ型であって、焼結体組成が、
１．９８≦Ｘ≦２．０１
０．７２≦Ｙ≦０．９５
であり、ドーパントとして、１Ａ族のアルカリ金属、１Ｂ族の銅（Ｃｕ）、銀（Ａｇ）、金（Ａｕ）の少なくとも何れか一つの金属を添加して得ることを特徴とするマグネシウム、珪素、スズからなる熱電半導体である。
請求項３の発明は、１Ａ族のアルカリ金属は、カルボン酸塩として添加されることを特徴とする請求項１記載のマグネシウム、珪素、スズからなる熱電半導体の製造方法である。
請求項４の発明は、１Ａ族のアルカリ金属は、カルボン酸塩として添加されることを特徴とする請求項２記載のマグネシウム、珪素、スズからなる熱電半導体である。
The present invention was created with the object of solving these problems in view of the above circumstances. The invention of
When the thermoelectric semiconductor represented by is manufactured by sintering, the thermoelectric semiconductor is p-type, and the sintered body composition is
1.98 ≦ X ≦ 2.01
0.72 ≦ Y ≦ 0.95
Magnesium, silicon obtained by adding at least any one metal of 1A group alkali metal, 1B group copper (Cu), silver (Ag), gold (Au) as a dopant, This is a method for producing a thermoelectric semiconductor made of tin.
According to the second aspect of the present invention, the general chemical formula Mg X Si 1-Y Sn Y is obtained by subjecting raw materials magnesium, silicon and tin to a liquid-solid phase reaction.
In the thermoelectric semiconductor manufactured by sintering what is represented by the thermoelectric semiconductor is p-type, and the sintered body composition is
1.98 ≦ X ≦ 2.01
0.72 ≦ Y ≦ 0.95
Magnesium, silicon obtained by adding at least any one metal of 1A group alkali metal, 1B group copper (Cu), silver (Ag), gold (Au) as a dopant, It is a thermoelectric semiconductor made of tin.
The invention according to
The invention according to claim 4 is the thermoelectric semiconductor composed of magnesium, silicon, and tin according to
請求項１または２の発明とすることにより、マグネシウム、珪素、そしてスズを原料とした一般化学式
ＭｇＸＳｉ１−ＹＳｎＹ
で示される金属間化合物の焼結体について、ｎ型でなく、ｐ型の熱電半導体を、高温領域においてもｐ型を維持した安定性が高いものを得ることができることになる。
請求項３または４の発明とすることにより、ドーパントとして用いることができる反応性が高い１Ａ族の金属を、取扱いやすいものとして用いることができることになる。
According to the invention of
As for the sintered body of the intermetallic compound represented by the above, it is possible to obtain a p-type thermoelectric semiconductor which is not n-type and has high stability while maintaining p-type even in a high temperature region.
By making it the invention of
本発明は、マグネシウム（Ｍｇ）、ケイ素（Ｓｉ）、そしてスズ（Ｓｎ）の金属間化合物の焼結体からなる熱電半導体であって、一般化学式
ＭｇＸＳｉ１−ＹＳｎＹ
で表され、この場合にＸ、Ｙは、
１．９８≦Ｘ≦２．０１
０．７２≦Ｙ≦０．９５
のものが室温においてｐ型の熱電半導体であるという前述した知見に基づき、これを高温にしても安定したｐ型の熱半導体に維持できないか、ということでドーパントの添加について検討したところ、ドーパントとして１Ａ族のアルカリ金属、１Ｂ族の金、銀、銅の金属を添加したものは、比抵抗（キャリア濃度）の制御が可能になって高温でも安定したｐ型特性の熱電半導体を得ることができることを見出し、ここに本発明を完成した。
The present invention is a thermoelectric semiconductor comprising a sintered body of an intermetallic compound of magnesium (Mg), silicon (Si), and tin (Sn), and has a general chemical formula Mg X Si 1-Y Sn Y
In this case, X and Y are
1.98 ≦ X ≦ 2.01
0.72 ≦ Y ≦ 0.95
Based on the above-described knowledge that the semiconductor is a p-type thermoelectric semiconductor at room temperature, whether or not it can be maintained as a stable p-type thermal semiconductor even at a high temperature, the addition of a dopant was examined. Those added with Group 1A alkali metals and Group 1B gold, silver, and copper metals can control the specific resistance (carrier concentration) and obtain a thermoelectric semiconductor with stable p-type characteristics even at high temperatures. The present invention was completed here.
本発明において用いられるドーパントは、具体的には１Ａ族（アルカリ金属）のリチウム（Ｌｉ）、ナトリウム（Ｎａ）、カリウム（Ｋ）、ルビジウム（Ｒｂ）、セシウム（Ｃｓ）、１Ｂ族の銅（Ｃｕ）、銀（Ａｇ）、金（Ａｕ）の単独または複数を混合したものを用いることができる。
この場合において、１Ａ属のアルカリ金属は、単体で用いても良いが、単体では反応性が高く取り扱いに特に注意が必要なこともあり、そこで酢酸やステアリン酸として例示されるカルボン酸の塩として用いても効果があることが確認された。
Specifically, the dopants used in the present invention include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and group 1B copper (Cu). ), Silver (Ag), gold (Au), or a mixture of a plurality of them.
In this case, the alkali metal belonging to Group 1A may be used alone, but the single substance is highly reactive and may require special attention in handling. Therefore, as a salt of carboxylic acid exemplified as acetic acid or stearic acid, It was confirmed that it was effective even when used.
前記目的とする金属間化合物の合成方法であるが、原料をセットした状態の概略図を図１に、また金属間化合物を合成し、熱電特性を測定するまでの手順のフローチャートを図２に示す。
前記化学組成
ＭｇＸＳｉ１−ＹＳｎＹ
において、Ｙ＝０．７５としたときの合成条件および焼結条件を図３（Ａ）の表図で示す。
熱電半導体の具体的な合成方法としては、予め空焼きしたカーボンボードについて紙ウエスでカーボン粉をよく拭き取ったものを用意し、このものに、図１に示すように、Ｍｇ、Ｓｉ、Ｓｎを充填することになるが、Ｍｇについては角形状、丸形状、球形状等、任意の粒状でよいが約２〜１０ｍｍの大きさにしたものを用いる。Ｓｎについては平均粒径が約１〜３ｍｍ程度にした小粒状のものを用いる。さらにＳｉについては数十μｍ程度の微粉末としたものを用いる。そしてこのＳｉにドーパントの粉末を良く混ぜてＳｉ−ドーパント混合物にしたものについて、まず全体の１／３〜１／２程度をカーボンボードに底が見えなくなるよう均等状に敷く。ついでその上面に、Ｓｎの全体の１／３〜１／２を均等状に散らす。その上面に、Ｍｇの粒を並べる。このとき、互いに重なり合わないようにすることが好ましい。更にその上に、残りのＳｉ−ドーパント混合物およびＳｎを、Ｍｇを覆い隠すようにして均等状に被せる。
FIG. 1 shows a schematic diagram of the state in which raw materials are set, and FIG. 2 shows a flowchart of a procedure for synthesizing an intermetallic compound and measuring thermoelectric properties. .
The chemical composition Mg X Si 1-Y Sn Y
In FIG. 3A, the synthesis conditions and the sintering conditions when Y = 0.75 are shown in the table of FIG.
As a specific method for synthesizing a thermoelectric semiconductor, prepare a carbon board that has been pre-baked and wiped off with a paper waste and filled with Mg, Si, and Sn as shown in FIG. However, Mg may have any granular shape such as a square shape, a round shape, a spherical shape, etc., but a size of about 2 to 10 mm is used. As for Sn, small particles having an average particle diameter of about 1 to 3 mm are used. Further, Si used is a fine powder of about several tens of μm. And about this what mixed the powder of dopant well with Si and made Si-dopant mixture, first, about 1/3 to 1/2 of the whole is spread evenly so that the bottom cannot be seen on the carbon board. Next, 1/3 to 1/2 of the entire Sn is uniformly distributed on the upper surface. On the upper surface, Mg grains are arranged. At this time, it is preferable not to overlap each other. Furthermore, the remaining Si-dopant mixture and Sn are covered evenly so as to cover the Mg.
しかる後、カーボン蓋でカーボンボードの蓋をし、ジルコニウム（Ｚｒ）箔で包み込み、針金で縛った状態で電気炉に投入し、合成反応をさせる。合成反応の条件としては図３（Ａ）に示すように、０．１ＭＰａ（メガパスカル）のＡｒ（アルゴン）−Ｈ２（水素３％）雰囲気下、絶対温度１１７３Ｋ（９００℃）で４時間加熱し、液−固相反応をさせる。そして得られた固溶体を粉砕し分級して得られた３８〜７５μｍ（マイクロメートル）の粉末をカーボンダイスに入れ、ホットプレスにより加圧して焼結する。
After that, the carbon board is covered with a carbon lid, wrapped with zirconium (Zr) foil, and bound with a wire and placed in an electric furnace to cause a synthesis reaction. As a condition for the synthesis reaction, as shown in FIG. 3A, heating was performed at an absolute temperature of 1173 K (900 ° C.) for 4 hours in an Ar (argon) -H 2 (
さらに前記Ｙ＝０．７５としたときの焼結条件は図３（Ａ）の表図で示すように、原料粒径が前記３８〜７５μｍにしたものを内容形状が円柱状になるホットプレスに充填し、絶対温度１０２３Ｋ（７５０℃）の電気炉にて０．２ＭＰａのＡｒ雰囲気下でプレス圧５０ＭＰａの加圧条件で５時間のあいだ焼結し、このようにして目的とする単相の金属間化合物の焼結体を生成した。しかる後、カーボンダイスから取り出した焼結体を切り出し、研磨をしたものについて必要な熱電特性の測定をした。
同様にして前記化学組成としてＹ＝０．９５としたときの合成条件及び焼結条件を図３（Ｂ）に示すが、この場合の合成手順、焼結手順についてはＹ＝０．７５のものと同様にした。
Further, as shown in the table of FIG. 3A, the sintering condition when Y = 0.75 is a hot press in which the raw material particle diameter is 38 to 75 μm and the content shape is cylindrical. Filled and sintered in an electric furnace with an absolute temperature of 1023 K (750 ° C.) in a 0.2 MPa Ar atmosphere for 5 hours under a press pressure of 50 MPa, and thus the desired single-phase metal A sintered body of an intermetallic compound was produced. Thereafter, the sintered body taken out from the carbon die was cut out and the necessary thermoelectric properties were measured for the polished one.
Similarly, the synthesis conditions and the sintering conditions when Y = 0.95 as the chemical composition are shown in FIG. 3B. The synthesis procedure and the sintering procedure in this case are Y = 0.75. And so on.
次に、ドーパントとしてＬｉを用いて得た熱電半導体のものについて図４に示す表図に基づいて説明する。ここにおいて、図４に示すような原料組成になるようＭｇ、Ｓｉ、Ｓｎをそれぞれ秤量すると共に、ドーパントとしてステアリン酸リチウム、酢酸リチウムの粉末を、添加割合が図４に示す量（ｐｐｍ換算）になるよう秤量し、これらについて前述した手法に基づいて焼結体を製造し、該製造した焼結体について熱電特性を調べたところ、本発明が実施されていたものは全てのものがｐ型の伝導型を示した。
これらのゼーベック係数α（μＶ／Ｋ）、比抵抗ρ（Ωｍ）、熱伝導率κ（Ｗ／ｍＫ）、性能指数Ｚ（／Ｋ）の熱電特性を図４の表図に示した。
また、図５（Ａ）にＬｉ添加量とゼーベック係数αとの関係、同図（Ｂ）にＬｉ添加量と比抵抗ρとの関係、図６（Ａ）にＬｉ添加量と熱伝導率κとの関係、同図（Ｂ）にＬｉ添加量と性能指数Ｚとの関係のグラフ図をそれぞれ示す。尚、図４〜６にＳｎを含有しない金属間化合物Ｍｇ２Ｓｉにドーパントとしてステアリン酸リチウムを添加しないもの、したものについて同様にして焼結体を製造したものを参考例として記載する。
Next, a thermoelectric semiconductor obtained using Li as a dopant will be described with reference to a table shown in FIG. Here, Mg, Si, and Sn are weighed so as to have the raw material composition as shown in FIG. 4, and the powders of lithium stearate and lithium acetate as dopants are added to the amounts shown in FIG. 4 (in terms of ppm). The sintered body was manufactured based on the above-described method, and the thermoelectric characteristics of the manufactured sintered body were examined. As a result, all the samples in which the present invention was implemented were p-type. The conductivity type was shown.
The thermoelectric characteristics of these Seebeck coefficient α (μV / K), specific resistance ρ (Ωm), thermal conductivity κ (W / mK), and figure of merit Z (/ K) are shown in the table of FIG.
5A shows the relationship between the Li addition amount and the Seebeck coefficient α, FIG. 5B shows the relationship between the Li addition amount and the specific resistance ρ, and FIG. 6A shows the Li addition amount and the thermal conductivity κ. The graph of the relationship between Li addition amount and the figure of merit Z is shown in FIG. Incidentally, it describes those without addition of lithium stearate as a dopant Sn
さらに組成がＭｇ２．００Ｓｉ０．２５Ｓｎ０．７５の焼結体を、ドーパントとして酢酸リチウムを２５０００ｐｐｍ、３５０００ｐｐｍ添加して得たものの温度Ｔとゼーベック係数との関係を図７（Ａ）に、同じくドーパントを添加したて得たものの温度（１０００／Ｔ）と比抵抗との関係を図７（Ｂ）に示す。
また上記組成の焼結体について、酢酸リチウムを２５０００ｐｐｍ添加して得たものの温度（１０００／Ｔ）と熱伝導率との関係を図８（Ａ）に、同じくドーパントを添加して得たものの温度と性能指数との関係を図８（Ｂ）に示す。
この結果から、ドーパントとして酢酸リチウムを用いたものは、３００Ｋの室温から７５０Ｋの高温に至るまでゼーベック係数がプラスの値を示していることが観測され、これによって高温でも安定したｐ型の伝導型を維持できることが確認された。
Further, FIG. 7A shows the relationship between the temperature T and the Seebeck coefficient of a sintered body having a composition of Mg 2.00 Si 0.25 Sn 0.75 added with 25000 ppm and 35000 ppm of lithium acetate as a dopant. Similarly, FIG. 7B shows the relationship between the temperature (1000 / T) obtained by adding the dopant and the specific resistance.
In addition, regarding the sintered body having the above composition, the relationship between the temperature (1000 / T) obtained by adding 25,000 ppm of lithium acetate and the thermal conductivity is shown in FIG. FIG. 8B shows the relationship between and the figure of merit.
From this result, it is observed that the one using lithium acetate as a dopant shows a positive value of the Seebeck coefficient from a room temperature of 300 K to a high temperature of 750 K, and thereby a stable p-type conductivity type even at a high temperature. It was confirmed that
次に、ドーパントとして銀を用い、図９に示す配合組成で熱電半導体を製造し、これらについて前記同様に熱電特性を調べたところ、何れも伝導型はｐ型であった。図９に熱電特性を示す。
そして次に、焼結体組成としてＭｇ２．００Ｓｉ０．２５Ｓｎ０．７５、Ｍｇ２．００Ｓｉ０．０５Ｓｎ０．９５の熱電半導体について、ドーパントであるＡｇ（金属粉末）添加量とゼーベック係数との関係、Ａｇ添加量と比抵抗との関係を図１０（Ａ）（Ｂ）にそれぞれ示す。さらにＡｇ添加量と熱伝導率との関係、Ａｇ添加量と性能指数との関係を図１１（Ａ）（Ｂ）にそれぞれ示す。尚、図９〜１１にＳｎを含有しない金属間化合物Ｍｇ２Ｓｉにドーパントとして銀を添加しないもの、したものについて同様にして焼結体を製造したものを参考例として記載する。
Next, thermoelectric semiconductors were produced using the compounding composition shown in FIG. 9 using silver as a dopant, and the thermoelectric characteristics were examined in the same manner as described above. As a result, the conductivity type was p-type. FIG. 9 shows the thermoelectric characteristics.
Next, with respect to thermoelectric semiconductors of Mg 2.00 Si 0.25 Sn 0.75 and Mg 2.00 Si 0.05 Sn 0.95 as sintered body compositions, the addition amount of Ag (metal powder) as a dopant and FIGS. 10A and 10B show the relationship with the Seebeck coefficient and the relationship between the Ag addition amount and the specific resistance, respectively. Furthermore, the relationship between Ag addition amount and thermal conductivity, and the relationship between Ag addition amount and a figure of merit are shown in FIGS. 11A and 11B, respectively. Incidentally, it describes those without addition of silver as a dopant to the
さらにドーパントとしてセシウム（Ｃｓ）を用いて熱電半導体を製造したが、この場合の具体的な添加物としては酢酸セシウムを用いた。そして図１１に示すように組成がＭｇ２．００Ｓｉ０．２５Ｓｎ０．７５となる焼結体を、セシウム添加量を異ならして熱電半導体を得たところ、これらの伝導型は何れもｐ型であった。図１２に熱電特性を示す。 Further, a thermoelectric semiconductor was produced using cesium (Cs) as a dopant, and cesium acetate was used as a specific additive in this case. Then, as shown in FIG. 11, when a sintered body having a composition of Mg 2.00 Si 0.25 Sn 0.75 was obtained with different amounts of cesium added, thermoelectric semiconductors were obtained. It was a mold. FIG. 12 shows the thermoelectric characteristics.
またこれらの結果から、Ｍｇの組成をわずかに変化させることでｎ型、ｐ型の各熱電特性を示すＭｇ−Ｓｉ−Ｓｎの半導体を得られたことにもなる。
このことは、Ｓｉ、Ｓｎの組成が同じものにおいて、Ｍｇの添加割合を僅かに変化させることで、ｎ型だけでなく、ｐ型の熱電半導体を、作製面上で大きな違いなく製造できることになって、製造効率に優れ、しかも熱電素子としての使用温度が同じものにでき、そのうえｐ−ｎ一体型のものを成形時に同じ接合技術が使用でき、さらには直接接合することができることになる。
In addition, from these results, an Mg—Si—Sn semiconductor exhibiting n-type and p-type thermoelectric characteristics can be obtained by slightly changing the Mg composition.
This means that not only n-type but also p-type thermoelectric semiconductors can be manufactured on the fabrication surface by changing the addition ratio of Mg slightly in the same composition of Si and Sn. In addition, the manufacturing temperature is excellent and the use temperature as the thermoelectric element can be made the same. Moreover, the same joining technique can be used for the pn integrated type at the time of molding, and further, direct joining can be performed.
Claims (4)
ＭｇＸＳｉ１−ＹＳｎＹ
で示される熱電半導体を焼結して製造するにあたり、
該熱電半導体はｐ型であって、焼結体組成が、
１．９８≦Ｘ≦２．０１
０．７２≦Ｙ≦０．９５
であり、
ドーパントとして、１Ａ族のアルカリ金属、１Ｂ族の銅（Ｃｕ）、銀（Ａｇ）、金（Ａｕ）の少なくとも何れか一つの金属を添加して得ることを特徴とするマグネシウム、珪素、スズからなる熱電半導体の製造方法。 General chemical formula Mg X Si 1-Y Sn Y by liquid-solid phase reaction of raw materials magnesium, silicon and tin
In manufacturing the thermoelectric semiconductor shown in
The thermoelectric semiconductor is p-type, and the sintered body composition is
1.98 ≦ X ≦ 2.01
0.72 ≦ Y ≦ 0.95
And
It is made of magnesium, silicon, or tin, which is obtained by adding at least one metal of 1A group alkali metal, 1B group copper (Cu), silver (Ag), and gold (Au) as a dopant. Thermoelectric semiconductor manufacturing method.
ＭｇＸＳｉ１−ＹＳｎＹ
で示されるものを焼結して製造した熱電半導体において、
該熱電半導体はｐ型であって、焼結体組成が、
１．９８≦Ｘ≦２．０１
０．７２≦Ｙ≦０．９５
であり、
ドーパントとして、１Ａ族のアルカリ金属、１Ｂ族の銅（Ｃｕ）、銀（Ａｇ）、金（Ａｕ）の少なくとも何れか一つの金属を添加して得ることを特徴とするマグネシウム、珪素、スズからなる熱電半導体。 General chemical formula Mg X Si 1-Y Sn Y by liquid-solid phase reaction of raw materials magnesium, silicon and tin
In the thermoelectric semiconductor manufactured by sintering what is shown in
The thermoelectric semiconductor is p-type, and the sintered body composition is
1.98 ≦ X ≦ 2.01
0.72 ≦ Y ≦ 0.95
And
It is made of magnesium, silicon, or tin, which is obtained by adding at least one metal of 1A group alkali metal, 1B group copper (Cu), silver (Ag), and gold (Au) as a dopant. Thermoelectric semiconductor.
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