Bi8Se7: 移動性の向上と室温近くの熱電性能を高める分散型インターレイヤ π-ボンド相互作用
Fei Jia1,2, Yong-Yi Liu1, Yi-Fan Zhang1
1Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, China.
Journal of the American Chemical Society
|June 24, 2020
まとめ
[Bi2][Bi2Q3]熱電性材料の電気伝導性を向上させることを発見した. この発見は 効率的な 室温に近い エネルギー変換装置の開発への道を開きます
科学分野:
- 材料科学
- 固体物理学
- エネルギー変換
背景:
- ポータブル電子機器に電力を供給するには,環境の熱から電気へのエネルギー変換が不可欠です.
- 室温に近い熱電性材料は希少で,応用が限られている.
- [Bi2][Bi2Q3]ファミリーは,費用対効果が高く,毒性が低い熱電性材料を開発するためのプラットフォームを提供します.
研究 の 目的:
- [Bi2][Bi2Q3]ファミリーの間層の電気伝導性 (σ) を高めるメカニズムを調査する.
- インターレイヤードロカライズドπ結合の強さを評価するための新しいインデックス (F) を提案する.
- このファミリー内の新しい熱電気材料を特定し,実験的に検証する.
主な方法:
- 電子構造と結合を分析するための第一原理計算.
- π結合の強さを定量化するための経験的指数 (F = Dp,p(Bi0) /Dp,p(Bi3+)) の開発と応用.
- Bi8Se7とTe/SbでコードされたBi5.6Sb2.4Se5Te2の合成と特徴づけ
- キャリアモビリティ (μH),電気伝導性 (σ),シーベック係数,およびメリット数 (ZT) を含む熱電特性測定.
主要な成果:
- デロカライズされたπ結合相互作用は,層間のキャリアモビリティ (μH) と電気伝導性 (σ) を著しく増加させる.
- 1の最適なF値はμHを最大化し,F=1.06のBi8Se7はμH (33.08cm2/(Vs)) と σを増加させる.
- Bi5.6Sb2.4Se5Te2でのTe/Sbコドピングは,シーベック係数を増加させ,ZTは425Kで約0.7で,予測されるZTは約1.2である.
- 実験結果は,Bi8Se7とコドプ化物質の理論的予測を裏付けている.
結論:
- デロカライズされたπ結合は[Bi2][Bi2Q3]熱電学における層間伝導性を改善する鍵となる.
- Bi8Se7は,室温近くの熱電特性を持つ有望なn型材料です.
- Te/Sb コドーピングは熱電性能をさらに最適化し,高度なエネルギー収集アプリケーションの可能性を示唆しています.
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