Chemical Homogeneity in Entropy-Stabilized Complex Metal Oxides

Ali Moballegh, Christina M. Rost, Jon-Paul Maria and Elizabeth C. Dickey, 2015

Image courtesy of Microsc. Microanal.

Abstract

Innovation in new mixtures of constituents can lead to discover exciting new materials with unexpected properties and revolutionary applications [1,2]. It is known, the Gibbs energy needs to be minimized, as the main requirement, to achieve a stable single phase compound. Conventional approach to minimize the total energy of system is searching for a large and negative enthalpy. However, in this work, we show that the phase stability can be reached where the configurational entropy is maximized with mixing as many diverse elements as possible.

Impact Statement

In this work, five binary metal oxides, MgO, CaO, NiO, CuO, and ZnO, were chosen considering favored coordination, iconic radii, and diversity in crystal structures. An equimolar mixture of the constituent metaloxide powders were mixed and pressed into ceramic pellets. The pellets were subsequently annealed in an air until equilibrium was achieved and then quenched to the room temperature.