Effects of thermal expansion and four-phonon interactions on the lattice thermal conductivity of the negative thermal expansion material <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>ScF</mml:mi> <mml:mn>3</mml:mn> </mml:msub> </mml:math>

Abstract

This work systematically investigates the lattice dynamics and phonon thermal transport behavior of the typical negative thermal expansion (NTE) material, cubic ${\mathrm{ScF}}_{3}$. By incorporating thermal expansion, the discrepancy between theoretically predicted and experimentally observed lattice thermal conductivity (${\ensuremath{\kappa}}_{\mathrm{L}}$) is resolved using self-consistent phonon theory, combined with the three- and four-phonon scattering. Our findings reveal that four-phonon interactions significantly increase the ${\ensuremath{\kappa}}_{\mathrm{L}}$ of ${\mathrm{ScF}}_{3}$, which contradicts the traditional intuitive impression that four-phonon interactions suppress thermal transport. This counterintuitive behavior is attributed to the hardening of two rotating phonon modes induced by quartic anharmonicity, suppressing anharmonic scattering and increasing the ${\ensuremath{\kappa}}_{\mathrm{L}}$. Furthermore, we show that thermal expansion enhances anharmonic scattering in ${\mathrm{ScF}}_{3}$, leading to a decrease in ${\ensuremath{\kappa}}_{\mathrm{L}}$. This suppression of ${\ensuremath{\kappa}}_{\mathrm{L}}$ becomes more pronounced at high pressures due to the significantly enhanced NTE behavior; for instance, the room-temperature ${\ensuremath{\kappa}}_{\mathrm{L}}$ of ${\mathrm{ScF}}_{3}$ is reduced by up to 59% at 0.6 GPa. Our work provides deeper insights into the effects of four-phonon interactions and thermal expansion on thermal transport properties.

Topics & Concepts