In this paper, we study the elastic properties of the entropy-stabilized oxide (Mg, Co, Ni, Cu, Zn)O, using experimental and first principles techniques. Our measurements of the indentation modulus on grains with a wide range of crystallographic orientations of the entropy-stabilized oxide revealed a high degree of elastic isotropy at ambient conditions. First principles calculations predict mild elastic anisotropy for the paramagnetic structure, which decreases when the system is considered to be non-magnetic. When the antiferromagnetic state of CoO, CuO and NiO is accounted for in the calculations, a slight increase in the elastic anisotropy is observed, suggesting a coupling between magnetic ordering and the orientation dependent elastic properties. Furthermore, an examination of the local structure reveals that the isotropy is favored through local ionic distortions of Cu and Zn - due to their tendency to form tenorite and wurtzite phases. The relationships between the elastic properties of the multicomponent oxide and those of its constituent binary oxides are reviewed. These insights open up new avenues for controlling isotropy for technological applications through tuning composition and structure in the entropy-stabilized oxide or the high entropy compounds in general.
@article{arxiv.2004.06613,
title = {On the Elastic Anisotropy of the Entropy-Stabilized Oxide (Mg, Co, Ni, Cu, Zn)O},
author = {Krishna Chaitanya Pitike and Andres Marquez-Rossy and Alexis Flores-Betancourt and De Xin Chen and Santosh KC and Valentino R. Cooper and Edgar Lara-Curzio},
journal= {arXiv preprint arXiv:2004.06613},
year = {2020}
}
Comments
52 pages, includes 29 pages supplemental materials, 5 figures