Localized Vibrational Modes in High-Entropy Oxides

Abstract

The existence of localized vibrational modes in the high-entropy oxide (MgCoNiCuZn)O is investigated using classical lattice dynamics. New empirical interatomic potentials for the cation-oxygen interactions in (MgCoNiCuZn)O are developed and are shown to yield superior agreement with the experimental crystal structures, dielectric constants, and phonon frequencies of the parent binary oxides. Various probes for localization are calculated and suggest (MgCoNiCuZn)O supports localized modes beyond a high-frequency mobility edge in the vibrational density-of-states.