Charge‐Induced Disorder Controls the Thermal Conductivity of Entropy‐Stabilized Oxides

TLDR

Introducing configurational entropy via unique atomic species can yield materials with improved mechanical and electrical properties, while large elemental property differences can impede phonon heat transport; recent advances in entropy‑stabilized ceramics now allow exploration of extreme disorder effects on thermal transport. The study aims to investigate how extreme disorder in entropy‑stabilized ceramics affects thermal transport. Local ionic charge disorder in single‑crystal entropy‑stabilized oxides reduces thermal conductivity to near the amorphous limit while preserving mechanical stiffness, giving these materials the highest elastic modulus to thermal conductivity ratio among isotropic crystals.

Abstract

Manipulating a crystalline material's configurational entropy through the introduction of unique atomic species can produce novel materials with desirable mechanical and electrical properties. From a thermal transport perspective, large differences between elemental properties such as mass and interatomic force can reduce the rate at which phonons carry heat and thus reduce the thermal conductivity. Recent advances in materials synthesis are enabling the fabrication of entropy-stabilized ceramics, opening the door for understanding the implications of extreme disorder on thermal transport. Measuring the structural, mechanical, and thermal properties of single-crystal entropy-stabilized oxides, it is shown that local ionic charge disorder can effectively reduce thermal conductivity without compromising mechanical stiffness. These materials demonstrate similar thermal conductivities to their amorphous counterparts, in agreement with the theoretical minimum limit, resulting in this class of material possessing the highest ratio of elastic modulus to thermal conductivity of any isotropic crystal.