Influence of oxygen vacancies on the structure and magnetic properties of high entropy (Co,Cr,Fe,Mn,Ni)3O4 ceramics

作者：Sun, Xiaoyan; Zeng, Xianghui; He, Xuan; Fang, Wei; Du, Xing; Li, Weixin; Zhao, Lei; Chen, Hui^*

来源：Journal of Alloys and Compounds, 2022, 925: 166560.

DOI：10.1016/j.jallcom.2022.166560

• High-entropy oxide
• Spinel
• Oxygen vacancy
• Magnetic properties

This research revealed the influence of oxygen vacancies on the structure and magnetic properties of high entropy (Co,Cr,Fe,Mn,Ni)(3)O-4 ceramics. High entropy (Co,Cr,Fe,Mn,Ni)(3)O-4 and (Co,Cr,Fe,Mn,Ni)(3)O4-n ceramics with a single-phase spinel structure was synthesized by surfactant-assisted hydrothermal technology combined with a heat treatment method. X-ray diffraction Rietveld analysis showed that the lattice constant of (Co,Cr,Fe,Mn,Ni)(3)O-4 and (Co,Cr,Fe,Mn,Ni)(3)O4-n were 8.346 A and 8.327 angstrom, whereas the lattice distortion were 0.314-0.007, respectively. Magnetic studies indicate that all synthesized samples exhibit typical ferrimagnetism at 5-300 K. Compared with (Co,Cr,Fe,Mn,Ni)(3)O-4, the Hc of (Co,Cr,Fe,Mn,Ni)(3)O4-n increased from 7.99 center dot 10 Oe to 9.03 center dot 10 Oe, the Ms increased from 4.38 emu center dot g(-1) to 6.59 emu center dot g(-1) at room temperature. The theory calculations reveal that the 3d TM atoms are origin of the magnetism. And compared with (Co,Cr,Fe,Mn,Ni)(3)O-4, the spin density of metal atoms of (Co,Cr,Fe,Mn,Ni)(3)O4-n increases and the direction change. Our observation and theoretical calculations serve as a link between the defect, structure, and magnetic properties, providing a new sight into understanding the structural origin of the changes in magnetic properties of high entropy ceramics.