X-raying Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O: disentangling elemental contributions in a prototypical high-entropy oxide

TL;DR

This study uses advanced X-ray techniques to analyze the individual contributions of elements in high-entropy oxides, revealing how specific ions influence structural distortions, magnetic interactions, and overall properties.

Contribution

It provides a detailed disentanglement of elemental effects in high-entropy oxides using multiple X-ray methods, highlighting the roles of Cu, Ni, and Mg ions.

Findings

Cu ions cause significant Jahn-Teller distortions

Ni and Mg ions promote positional order

Magnetic excitations and interactions are characterized

Abstract

We employ several X-ray based techniques, including X-ray diffraction, absorption and resonant inelastic scattering, to disentangle the contributions of individual chemical species to the structural, electronic and magnetic properties of high-entropy oxides. In the benchmark compound Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O and related systems, we unambiguously resolve a sizable Jahn-Teller distortion at the Cu sites, more pronounced in the absence of Ni2+ and Mg2+, suggesting that these ions promote positional order, whereas Cu2+ ions act to destabilize it. Moreover, we detect magnetic excitations and estimate the strength of the interactions between pairs of different magnetic elements. Our results provide valuable insights into the role of the various chemical species in shaping the physical properties of high-entropy oxides.