Disorder-Driven Dissolution: Cation Congruence in a High-Entropy Oxide Under Acidic Conditions

Abstract

High-entropy oxides offer tunable functional properties, yet their acidic dissolution is largely unexplored. We show that (MgCoNiCuZn)0.2O dissolves congruently in dilute nitric acid, releasing all five cations together. A physical mixture and a three-cation solid solution both dissolve incongruently, showing that a single phase alone does not ensure congruent release.