Evidence for Jahn-Teller compression in the (Mg, Co, Ni, Cu, Zn)O entropy-stabilized oxide: A DFT study

The local atomic configuration and the electronic structure of the octahedral Cu2+ centers in the entropy-stabilized oxides (ESOs), (MgCoNiZn)1−xCuxO (x = 0.13, 0.2, 0,.26), have been investigated using density functional theory. The calculated Cu–O bond lengths combined with the analysis of the electronic density of states indicate that ∼10% of the CuO6 octahedra in ESOs undergo Jahn-Teller (JT) compression. This unexpected behavior is likely related to the structural constraints imposed by the rocksalt lattice and reflects the competition between the regular octahedral environment preferred by the cations in the system and the JT distortion imposed by the Cu-centers. The orientation of the distortions appears to be random, in agreement with recent experimental results.