Strain-driven lone pair electron expression for thermal transport in BiCuSeO

作者：Da Wan, Shulin Bai, Sirui Fan, Xiao Xiang, Zhen Li, Yu Liu, Peng Kang, Lei Zheng, Li‐Dong Zhao, Huibin Xu · 发表于：Nature Communications · 年份：2025 · DOI：10.1038/s41467-025-61506-6 · 被引用次数：32 · 研究领域：Advanced Thermoelectric Materials and Devices、Thermal properties of materials、Thermal Expansion and Ionic Conductivity

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. This study shows that tensile strain continuously tunes lone-pair expression in BiCuSeO, increases lattice disorder and phonon scattering, and lowers thermal conductivity, offering an effective approach to control heat transport in materials.