PbTeにおけるNaドーピング:溶解性,帯収束,相境界マッピング,および熱電性
Priyanka Jood1, James P Male2, Shashwat Anand2
1Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
Journal of the American Chemical Society
|August 14, 2020
まとめ
鉛テルリド (PbTe) 熱電器におけるナトリウム溶解性の限界を超えると,性能が向上する. より高いナトリウムドーピングは,帯構造を最適化し,望ましくない伝導を抑制することにより,熱電性値 (zT) を改善します.
科学分野:
- 材料科学
- 固体物理学
- 熱電気エネルギー変換
背景:
- 熱電気材料は熱を電気に変換し,鉛テルリド (PbTe) は主要なp型材料である.
- PbTe熱電学を最適化するには,Pb0.98Na0.02Teが一般的な高性能マトリックスであるドーピングがしばしば含まれます.
研究 の 目的:
- Pb1-xNaxTeの熱電性能を,典型的な溶解性限界 (x > 0.02) を超えるナトリウム含有量 (x) で調査する.
- これらの過剰ドーピングされた材料の熱電性値 (zT) の強化の背後にあるメカニズムを解明する.
主な方法:
- Pb1-xNaxTe (0.01 ≤ x ≤ 0.04) の計算モデリングと実験合成
- 高温X線 difraktionとホールキャリア濃度測定
- バンド構造の収束と双極伝導抑制の分析
主要な成果:
- 高温で観察されたNaの溶解性の向上 x > 0.02で,Naは格子に入りますが,電気的に補償されます.
- より高いNa濃度によるPbTeにおけるLとSの値帯間の帯域収束.
- 双極伝導の抑制とシーベック係数の増加により,Pb0.96Na0.04TeのzTが2に近づく.
結論:
- PbTeの溶解性限界を超えたNaドーピングは,熱電性能を大幅に高めることができます.
- 段階図のアプローチは,溶解性を理解し,高性能ナドープされたPbTeの繰り返し合成を導くのに役立ちます.
- Pb0.96Na0.04Teは,Pb0.98Na0.02Teと比較して,p型PbTe熱電性を最適化するための優れた出発点を提供します.
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