Dopant-modulated lattice softening drives drastic thermal conductivity reduction in β-FeSi2 thermoelectrics
Abstract
Suppressing lattice thermal conductivity (K_lat) is pivotal for thermoelectric efficiency. While traditional strategies rely heavily on phonon scattering from mass- and size-mismatches, we demonstrate a robust K_lat suppression mechanism driven by dopant-induced lattice stiffness modulation. Through a comparative analysis of p-type (Mn) and n-type (Co, Ir) doping in the β-FeSi2 model system, we show that Co and Ir doping significantly reduce K_lat. Notably, Co doping achieves a ~71% reduction at 300 K even without significant mass and size contrast. By correlating transport data with neutron powder diffraction, heat capacity, and Raman spectroscopy, we reveal anomalous lattice expansion, a substantial reduction in Debye temperature, and marked vibrational redshift and broadening. These systematic changes provide strong evidence for atomic-scale lattice softening and a fundamental weakening of interatomic force constants, which synergistically lower phonon group velocities and amplify anharmonic scattering. Our findings establish lattice stiffness manipulation as a powerful strategy for thermal management, offering a distinct design pathway beyond traditional mass- and strain-fluctuation models.
Versions
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BibTeX
@misc{zhang2026dopantmodulated,
title = {{Dopant-modulated lattice softening drives drastic thermal conductivity reduction in β-FeSi2 thermoelectrics}},
author = {Cuiping Zhang and Qingyong Ren and Yangfan Cui and Chen Chen and Songbai Hu and Shengnan Dai and Chin-Wei Wang and Wanju Luo and Dexiang Gao and Bao Yuan and Junying Shen and Fan Chen and Wei Xu and Yuting Li and Mingfang Shu and Xiaoli Huang and Pengfei Qiu and Jie Ma},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.32261},
eprint = {2609.32261},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.32261},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Dopant-modulated lattice softening drives drastic thermal conductivity reduction in β-FeSi2 thermoelectrics
AU - Cuiping Zhang
AU - Qingyong Ren
AU - Yangfan Cui
AU - Chen Chen
AU - Songbai Hu
AU - Shengnan Dai
AU - Chin-Wei Wang
AU - Wanju Luo
AU - Dexiang Gao
AU - Bao Yuan
AU - Junying Shen
AU - Fan Chen
AU - Wei Xu
AU - Yuting Li
AU - Mingfang Shu
AU - Xiaoli Huang
AU - Pengfei Qiu
AU - Jie Ma
PY - 2026
DA - 2026/09/29
PB - arXiv
DO - 10.48550/arxiv.2609.32261
UR - https://arxiv.org/abs/2609.32261
AB - Suppressing lattice thermal conductivity (K_lat) is pivotal for thermoelectric efficiency. While traditional strategies rely heavily on phonon scattering from mass- and size-mismatches, we demonstrate a robust K_lat suppression mechanism driven by dopant-induced lattice stiffness modulation. Through a comparative analysis of p-type (Mn) and n-type (Co, Ir) doping in the β-FeSi2 model system, we show that Co and Ir doping significantly reduce K_lat. Notably, Co doping achieves a ~71% reduction at 300 K even without significant mass and size contrast. By correlating transport data with neutron powder diffraction, heat capacity, and Raman spectroscopy, we reveal anomalous lattice expansion, a substantial reduction in Debye temperature, and marked vibrational redshift and broadening. These systematic changes provide strong evidence for atomic-scale lattice softening and a fundamental weakening of interatomic force constants, which synergistically lower phonon group velocities and amplify anharmonic scattering. Our findings establish lattice stiffness manipulation as a powerful strategy for thermal management, offering a distinct design pathway beyond traditional mass- and strain-fluctuation models.
ER -