Effect of Co-Zr doping in the M-Type barium hexaferrite BaCoxZrxFe(12- 2x)O19: A Möss

Abstract

M- type hexagonal ferrites BaCoxZrxFe (12-2x)O19 (x = 0, 0.4 & 1.0) have been prepared by a sol-gel route. Mössbauer Spectroscopy is employed to probe the changes in the structural and magnetic properties at the microscopic levels in these Ba-haxaferrites where magnetic (Co2+), and non-magnetic (Zr 4+) ions have been substituted for Fe3+. Structure analysis, by Rietveld refinements of X-ray diffraction patterns, reveals that the substitution is preferred at octahedral 4f2 site up to x = 0.4 dopant concentration whereas, at higher concentration (x ∼ 1.0), Co 2+ ions enter into 4f2 while Zr4+ ions occupy both 4f2 and trigonal bipyramidal 2b (pseudotetrahedral) sites. The maximum substitution was attained at x = 1.0. This study reveals that site preferences depend upon both the nature of dopants and their concentration. The substitution causes a decrease in hyperfine field for all five crystallographic sites.