Micro-structural and magnetic analysis of spinel high entropy oxides synthesized by two-step pressureless sintering provides insight into high entropy ceramics

Abstract

High-entropy oxides are novel materials consisting of many metallic elements of equal proportions. Hence, the complex structure of high-entropy oxides leads to interesting properties. In this work, seven single-phase high entropy oxides were synthesized by two-step pressureless sintering. According to the experimental XRD data, all samples are found in the cubic crystal structure with the Fd-3m space group. This result shows that high entropy oxides have a high possibility of phase formation. For all samples, the EDS results show that all expected elements have similar elements content. The magnetization curves show that the magnetic properties change systematically with the changes in the high-entropy stable oxide composition. The seven different samples are divided into three groups for comparison. In group 1, with the substitution of iron for zinc, Hc increased from 19 Oe to 221 Oe, while Ms changed slightly. In group 2, the substitution of zinc for nickel leads to the rapid weakening of magnetism. In group 3, with nickel replacing cobalt, Ms increased from 15.060 emu/g to 19.801 emu/g, and Hc decreased from 28 Oe to 11 Oe. The complex element composition makes high entropy materials have great development space in the field of magnetic materials. Thus, the magnetic properties of the high-entropy spinel oxides can be adjusted according to this concept.