Magnetic, Mössbauer and Raman spectroscopy of nanocrystalline Dy3+-Cr3+ substituted barium hexagonal ferrites

Abstract

Dy3+-Cr3+ substituted barium hexaferrite was synthesized using sol-gel method. The variation in the saturation and remnant magnetization suggest that the amount of Cr3+ ions occupying 4f2 crystallographic site is greater than those occupying 12k and 2a crystallographic sites thereby resulting in increased saturation and remnant magnetization. The decrease in saturation and remnant magnetization indicate that Cr3+ ions replaces Fe3+ ions at 12k and 2a site because the net magnetic moment of Cr3+ (3 μB) is less than that of Fe3+ (5 μB). Ligand theory and analysis of Mössbauer parameters also suggest that Cr3+ ions occupy 4f2, 2b, 2a, and 12 k sites. This shows that various proportion of Cr3+ replaces Fe3+ ions at different sites depending on factors such as site preference, magnetic moment of Cr3+ ion, isomer shift, hyperfine splitting, quadruple splitting, relative area as well as anisotropy constant. Raman analysis complements the findings of the magnetic and Mössbauer analysis.