On the thermal and mechanical properties of Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2O across the high-entropy to entropy-stabilized transition

Abstract

As various property studies continue to emerge on high entropy and entropy-stabilized ceramics, we seek a further understanding of the property changes across the phase boundary between "high-entropy"and "entropy-stabilized"phases. The thermal and mechanical properties of bulk ceramic entropy stabilized oxide composition Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O are investigated across this critical transition temperature via the transient plane-source method, temperature-dependent x-ray diffraction, and nano-indentation. The thermal conductivity remains constant within uncertainty across the multi-to-single phase transition at a value of ≈2.5 W/mK, while the linear coefficient of thermal expansion increases nearly 24% from 10.8 to 14.1 × 10-6 K-1. Mechanical softening is also observed across the transition.