Wan Da, Bai Shulin, Fan Sirui, Xiang Xiao, Li Zhen, Liu Yu, Kang Peng, Zheng Lei, Zhao Li-Dong, Xu Huibin
School of Materials Science and Engineering, Beihang University, Beijing, China.
State Key Laboratory of Artificial Intelligence for Material Science, Beihang University, Beijing, China.
Nat Commun. 2025 Jul 8;16(1):6284. doi: 10.1038/s41467-025-61506-6.
The stereochemical activity of lone-pair electrons critically influences lattice anharmonicity and thermal transport in crystals. However, traditional chemical substitution methods lack continuity and reversibility. We propose a strain-engineered bond angle distortion strategy in layered BiCuSeO to continuously modulate lone-pair electrons. Theoretically, tensile strain reduces the O-Bi-O bond angle, expands lone-pair electron spatial distribution, and decreases Bi-O bond charge overlap, intensifying Bi atom anharmonic vibrations. Furthermore, tensile strain induces reverse O atom vibrations and strong lattice dynamic disorder, lowering the phonon band gap and enhancing anharmonic phonon-phonon interactions and Umklapp scattering. Importantly, strain modulates lone-pair electron distribution and interaction strength without uniformly weakening long-range interatomic forces. As a result, 4% tensile strain reduces lattice thermal conductivity of BiCuSeO to 0.53 W/mK (54% decrease) at 300 K. This work establishes a multiscale framework linking strain, lone-pair electron behavior, and phonon dynamics, enabling robust and continuous control of thermal transport properties.
孤对电子的立体化学活性对晶体中的晶格非谐性和热输运有着至关重要的影响。然而，传统的化学替代方法缺乏连续性和可逆性。我们提出了一种在层状BiCuSeO中通过应变工程实现键角畸变的策略，以连续调节孤对电子。理论上，拉伸应变减小了O-Bi-O键角，扩展了孤对电子的空间分布，并降低了Bi-O键电荷重叠，增强了Bi原子的非谐振动。此外，拉伸应变引发了O原子的反向振动和强烈的晶格动力学无序，降低了声子带隙，增强了非谐声子-声子相互作用和Umklapp散射。重要的是，应变在不统一削弱长程原子间力的情况下调节孤对电子分布和相互作用强度。结果，4%的拉伸应变在300 K时将BiCuSeO的晶格热导率降低至0.53 W/mK（降低了54%）。这项工作建立了一个连接应变、孤对电子行为和声子动力学的多尺度框架，实现了对热输运性质的稳健且连续的控制。
