Bi8Se7: 分离的介层 π-键相互作用 增强载体的移动性和在室温附近的热电性能
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
概括
研究人员发现,移位的π键增强了[Bi2][Bi2Q3]热电材料的电导率. 这一发现为开发高效的室温能量转换装置铺平了道路.
科学领域:
- 材料科学
- 固态物理
- 能源转换
背景情况:
- 环境热电转换对于供电便携式电子设备至关重要.
- 接近室温的热电材料稀缺,限制了应用.
- [Bi2][Bi2Q3]家族为开发具有成本效益和毒性较低的热电材料提供了一个平台.
研究的目的:
- 研究[Bi2][Bi2Q3]家族中增强层间电导率 (σ) 的机制.
- 提出一个新的指数 (F) 来评估层间移位的π键强度.
- 识别和实验验证这一家族中的新型热电材料.
主要方法:
- 分析电子结构和结合的第一原则计算.
- 开发和应用一个经验指数 (F = Dp,p(Bi0) / Dp,p(Bi3+)) 来量化π键强度.
- 合成和表征Bi8Se7和Te/Sb编码的Bi5.6Sb2.4Se5Te2.
- 测量热电性质,包括载体流动性 (μH),电导率 (σ),西贝克系数和功率值 (ZT).
主要成果:
- 移位的π键相互作用显著增加了层间载体的移动性 (μH) 和电导率 (σ).
- 1的最佳F值最大化了μH;F=1.06的Bi8Se7显示了增强的μH (33.08 cm2/(Vs)) 和σ.
- 在Bi5.6Sb2.4Se5Te2中的Te/Sb配合增强了Seebeck系数,在425K达到~0.7的ZT,预测的ZT为~1.2.
- 实验结果证实了对Bi8Se7和合材料的理论预测.
结论:
- 移位的π键是改善[Bi2][Bi2Q3]热电中的层间导电性的关键.
- Bi8Se7是一种有前途的n型材料,在室温附近具有增强的热电特性.
- Te/Sb配合进一步优化了热电性能,表明了先进的能量采集应用的潜力.
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