Effect of Fe substitution on the cation distribution and magnetic properties of CoCr2-xFexO4 (x = 0.6 to 1.0) nanoparticles. (January 2021)

• Record Type: Journal Article
• Authors: Kumar, D.; Pandey, G.C.; Banerjee, A.; Mahmoud, A.; Rath, Chandana
• Is Part Of: Journal of physics and chemistry of solids. Volume 148(2021)
• Publication Date: 2021-01
• Subjects: Nanoparticles -- EXAFS analysis -- Mössbauer analysis -- Spin glass transition; Solids -- Periodicals; Solides -- Périodiques; Solids; Periodicals; 530.41
• DOI: 10.1016/j.jpcs.2020.109590
• Languages: English
• ISSNs: 0022-3697

Abstract

Abstract: Evolution of the structure, microstructure, cation distribution, and magnetic properties of CoCr2- x Fe x O4 nanoparticles with increase in x from 0.6 to 1.0 synthesized through a coprecipitation technique is demonstrated. While X-ray diffraction shows a cubic phase with space group F d 3 ‾ m, the cation distribution qualitatively examined by extended X-ray absorption fine structure is further quantified by Mössbauer spectroscopic measurements. We reveal that although Cr 3+ ions have a strong preference for the B site, Fe 3+ and Co 2+ ions are found to be distributed among A and B sites. As a consequence, the normal spinel CoCr2 O4 transforms to a mixed spinel type showing a decrease in the degree of inversion of Fe ions from 30% to 7% at the tetrahedral ( A ) site with increase in x from 0.6 to 1.0, whereas Fe 3+ ions are found to be equally distributed among A and B sites for x = 0.3. The paramagnetic to ferrimagnetic transition temperature, T C, is increased from 263 K for x = 0.6 to above room temperature for x = 1.0 compared with 97 K obtained for x = 0. The maximum magnetization calculated from the M-H curve increases from 0.18 μB per formula unit for x = 0–0.32 μB per formula unit for x = 0.6 and reaches 3.71 μB per formula unit for x = 1.0. The frequency-dependent ac susceptibility confirms spin glass behavior irrespective of the composition, including x = 0. Highlights: Enhancement of para-to ferrimagnetic transition with composition. Transformation normal spinel to mixed spinel after incorporation of Fe in CoCr2 O4 lattice. Enhancement of maximum magnetization and anisotropy constant with composition.