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Vacancy-induced phonon localization and lattice softening for reduced thermal conductivity in Mg(3)Sb(2) #MMPMID41347449
Zhang S; Zhang J; Ren L; Shao Y; Yan W; Tian M; Peng K; Lin P; Du Y
Phys Chem Chem Phys 2025[Dec]; ? (?): ? PMID41347449show ga
With the natural abundance, low cost, and compatibility with sustainable technologies, Mg(3)Sb(2) has emerged as a promising mid-temperature thermoelectric material. Intrinsic point defects, particularly vacancies, are common in Mg(3)Sb(2) and play a crucial role in shaping its thermoelectric properties, guiding experimental design and performance optimization. However, their impact on lattice thermal conductivity (kappa(L)) remains insufficiently understood. This work investigates the effects of Mg and Sb vacancies on the kappa(L) of Mg(3)Sb(2) using a neural network potential (NNP). Our results show that both types of vacancies significantly reduce kappa(L), primarily due to enhanced phonon-defect scattering. Comprehensive analyses of phonon dispersion, group velocities, mean square displacement (MSD), the phonon participation ratio (PPR), and elastic properties demonstrate that vacancies trigger pronounced phonon softening, slow down phonon transport, and promote strong localization, while simultaneously amplifying atomic vibrations and weakening interatomic bonding. This work clarifies the microscopic mechanisms by which point defects affect phonon transport and identifies defect engineering as an effective strategy for controlling thermal properties in thermoelectric materials.
Phys+Chem+Chem+Phys 2025 ; ? (?): ?
