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对称性破坏扩大了单对表达和轨道分裂,为有前途的链式热电学

Shulin Bai^1,2,3, Yixuan Hu^1,2,3, Shaoping Zhan³

¹School of Materials Science and Engineering, Beihang University, Beijing 100191, China.

Journal of the American Chemical Society

|July 21, 2025

概括

单对电子 (Lone-pair electrons,LPEs) 显著影响声子散射,而不是准低维材料中的量子封闭. 通过对称性破坏增强LPE表达增强热电性质.

科学领域:

材料科学
凝聚物质物理学
固态化学

背景情况:

电子不稳定性和量子封闭效应对低维材料的晶格动态和传输特性之间的相互作用尚未完全理解.
众所周知,单对电子 (Lone-pair electrons, LPE) 影响材料特性,但与维度效应相比,它们在声子散射中的特定作用需要进一步研究.

研究的目的:

研究单对电子 (LPE) 表达和尺寸缩小对声子散射和传输特性的相对贡献.
探索突破对称性的策略,以增强LPE表达及其对准低维系统的热电效率的影响.

主要方法:

准一维 (1D) PbSnS3和准二维 (2D) PbSnS2的实验合成和表征.
第一个原理计算和博尔兹曼运输理论分析声子行为和电子声子合.
用1D-Pb2Sn2S5Se进行对称破坏策略,以放大LPE表达.

主要成果:

准-1D PbSnS3显示较高的热传输比准-2D PbSnS2,与LPEs损失相关.
在1D系统中放大LPEs的表达促进了扩散式振动,并增强了Umklapp/正常声子散射.
与1D系统相比,在2D- PbSnS2中观察到LPEs表达和声散之间存在更强的相关性.
在1D系统中,对称性破裂导致轨道分裂和有效的电子声脱.

结论:

LPEs表达是声子散射的主要因素,超过了近乎低维的Pb-Sn-S-Se系统中的维度减小效应.
一种对称破坏策略有效地放大了LPEs,优化了电子-声子脱,并增强了热电潜力.
这些发现为设计先进的热电和热管理材料提供了洞察力,通过调整LPE在低维系统中.

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