Evolution of phonon transport across structural phase transitions in MgAgSb

TY - JOUR

T1 - Evolution of phonon transport across structural phase transitions in MgAgSb

AU - Shang, Luman

AU - Wu, Yu

AU - Liu, Yufan

AU - Zeng, Shuming

AU - Tang, Gang

AU - Liu, Chenhan

N1 - Publisher Copyright: © 2026 Published by Elsevier Ltd.

PY - 2026/5

Y1 - 2026/5

N2 - MgAgSb, a promising thermoelectric material, undergoes reversible phase transitions that drastically alter its thermal transport behavior. Using first-principles calculations, we systematically investigate the lattice thermal conductivity (κL[jls-end-space/]) of its three phases: α[jls-end-space/], β[jls-end-space/], and γ[jls-end-space/], revealing a progressive increase following (Formula presented). This trend originates from distinct scattering mechanisms. Four-phonon scattering substantially suppresses the particle-like conductivity (κp[jls-end-space/]) in the β and γ phases, while phonon-electron scattering provides a minor additional reduction. In contrast, the wave-like conductivity (κc[jls-end-space/]) from coherent phonon tunneling is highest in the complex α phase, contributing up to 44% of κL[jls-end-space/]. Notably, the temperature dependence of κL differs fundamentally between phases: in β[jls-end-space/], the weak κp variation arises from a decreasing Grüneisen parameter with temperature; in α[jls-end-space/], the strong rise in κc with temperature counteracts the decay of κp[jls-end-space/]. Our findings establish a comprehensive picture of thermal transport in MgAgSb, highlighting the phase-dependent interplay between particle-like and wave-like phonon contributions.

AB - MgAgSb, a promising thermoelectric material, undergoes reversible phase transitions that drastically alter its thermal transport behavior. Using first-principles calculations, we systematically investigate the lattice thermal conductivity (κL[jls-end-space/]) of its three phases: α[jls-end-space/], β[jls-end-space/], and γ[jls-end-space/], revealing a progressive increase following (Formula presented). This trend originates from distinct scattering mechanisms. Four-phonon scattering substantially suppresses the particle-like conductivity (κp[jls-end-space/]) in the β and γ phases, while phonon-electron scattering provides a minor additional reduction. In contrast, the wave-like conductivity (κc[jls-end-space/]) from coherent phonon tunneling is highest in the complex α phase, contributing up to 44% of κL[jls-end-space/]. Notably, the temperature dependence of κL differs fundamentally between phases: in β[jls-end-space/], the weak κp variation arises from a decreasing Grüneisen parameter with temperature; in α[jls-end-space/], the strong rise in κc with temperature counteracts the decay of κp[jls-end-space/]. Our findings establish a comprehensive picture of thermal transport in MgAgSb, highlighting the phase-dependent interplay between particle-like and wave-like phonon contributions.

KW - Electron–phonon coupling

KW - Four-phonon scattering

KW - Lattice thermal conductivity

KW - Phase transitions

KW - Wave-like phonon tunneling

UR - https://www.scopus.com/pages/publications/105036234410

U2 - 10.1016/j.mtphys.2026.102097

DO - 10.1016/j.mtphys.2026.102097

M3 - Article

AN - SCOPUS:105036234410

SN - 2542-5293

VL - 64

JO - Materials Today Physics

JF - Materials Today Physics

M1 - 102097

ER -