On the elastic anisotropy of the entropy-stabilized oxide (Mg, Co, Ni, Cu, Zn)O compound

Abstract

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 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 tendencies 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.

One Pot Synthesis, Surface and Magnetic Properties of Cu2O/Cu and Cu2O/CuO Nanocomposites

“…The magnetic properties of these composites are presented in Table 4. However, the values of magnetization and coercivity enabled us to calculate the anisotropy constant (K a = H c M s /0.98) for different samples [32]. The relation between the anisotropy constant and the egg white content is illustrated in Figure 10.…”

Computationally accelerated discovery of high entropy pyrochlore oxides

“…For example, significant enhancement in multicomponent systems compared to the end members is demonstrated for oxygen conduction in disordered pyrochlores [11], piezoelectric properties in perovskites [12], and thermal resistance in high entropy ceramics [13,14]. Furthermore, recent investigations of ionic conductivity and mechanical properties of entropy stabilized oxide in the rock salt structure revealed lithium superionic conductivity [15] and unusual elastic anisotropy [16], respectively.…”

Predicting the Phase Stability of Multicomponent High-Entropy Compounds

“…ESO and related materials with charge-compensating cationic substitutions have demonstrated colossal dielectric constant, which could be exploited for large- k dielectric materials for energy storage . These materials are also reported to exhibit large Li-ion conductivities and potentially large Li-storage capabilitiesboth of these properties are highly desirable for electrochemical energy conversion in battery applications. − Entropy stabilization could further benefit storage capacity retention and cycling stability in batteries. , Besides energy storage and electrochemical energy conversion, ESO has also been reported to exhibit long-range antiferromagnetic (AFM) ordering , and elastic anisotropy . Other high-entropy perovskite oxides and chalcogenides show potential photocatalytic hydrogen evolution activity and semiconducting functionalities, respectively.…”