Realization of Fine-Tuning the Lattice Thermal Conductivity and Anharmonicity in Layered Semiconductors via Entropy Engineering

Abstract

Entropy engineering is widely proven to be effective in achieving ultra-low thermal conductivity for well-performed thermoelectric and heat management applications. However, no strong correlation between entropy and lattice thermal conductivity is found until now, and the fine-tuning of thermal conductivity continuously via entropy-engineering in a wide entropy range is still lacking. Here, a series of high-entropy layered semiconductors, Ni_1−x(Fe_0.25Co_0.25Mn_0.25Zn_0.25)_xPS₃, where 0 ≤ x < 1, with low mass/size disorder is designed. High-purity samples with mixing configuration entropy of metal atomic site in a wide range of 0–1.61R are achieved. Umklapp phonon-phonon scattering is found to be the dominating phonon scattering mechanism, as revealed by the linear T⁻¹ dependence of thermal conductivity. Meanwhile, fine tuning of the lattice thermal conductivity via continuous entropy engineering at metal atomic sites is achieved, in an almost linear dependence in middle-/high- entropy range. Moreover, the slope of the κ - T⁻¹ curve reduces with the increase in entropy, and a linear response of the reduced Grüneisen parameter is revealed. This work provides an entropy engineering strategy by choosing multiple metal elements with low mass/size disorder to achieve the fine tuning of the lattice thermal conductivity and the anharmonic effect.