Atomic-scale tunable phonon transport at tailored grain boundaries and Their Impact on Thermal Conductivity
Abstract
Grain boundaries (GBs) strongly influence thermal transport in crystalline solids by disrupting lattice periodicity and scattering phonons. Due to the atomic-level disorder and structural complexity, a fundamental understanding of how specific GB geometries regulate nanoscale phonon behavior and macroscopic thermal conductivity has remained elusive. Here, using emerging atomic-resolution vibrational spectroscopy, we directly correlate GB structure, defect-specific vibrational states, and thermal transport in bicrystal strontium titanate with controlled tilt and twist angles. The phonon characterizations and thermal conductivity data reveal two distinct regimes, where low-angle tilt GBs (2deg, 6deg, 10deg) substantially modulate phonon populations and mode frequencies, resulting in pronounced changes in thermal conductivity, whereas high-angle tilt GBs (22deg, 36deg) exhibit weak conductivity variation due to saturated structural disorder and scattering. In contrast, twist GBs introduce periodic defect motifs that only locally tailor phonon transport. Our results suggest tilt and twist angles as complementary knobs for coarse and fine control of phonon propagation and cross-GB thermal transport, providing a predictive framework for thermal engineering in materials.
Cite
@article{arxiv.2405.07464,
title = {Atomic-scale tunable phonon transport at tailored grain boundaries and Their Impact on Thermal Conductivity},
author = {Xiaowang Wang and Chaitanya A. Gadre and Wanjuan Zou and Runqing Yang and Bin Xing and Christopher Addiego and Fenghui Gong and Toshihiro Aoki and Yujie Quan and Wei-Tao Peng and Yifeng Huang and Chaojie Du and Mingjie Xu and Xingxu Yan and Ruqian Wu and Shyue Ping Ong and Bolin Liao and Penghui Cao and Xiaoqing Pan},
journal= {arXiv preprint arXiv:2405.07464},
year = {2026}
}