Site Occupation and Magnetic Studies in La–Co-Substituted Barium Hexaferrite

In this work, preferential site occupation in La-Co-substituted barium hexaferrites was systematically investigated by micro-Raman and Mössbauer spectroscopy. The effect of substitution on the magnetic properties was studied by vibrating sample magnetometer. Raman studies showed redshift in 2a, 2b, and 4f₂ sites with Co and La substitution. The decrease in isomer shift and the relative sub-spectral area suggest that Co²⁺ ions preferably occupy 2a and 2b sites for Co-substituted sample. For La-Co substitution, Co also occupies 4f₂ site as evidenced by the reduction in hyperfine field. Anisotropic field calculated by the law of approaching saturation was found to decrease with substitution. Curie temperature showed a strong dependence on La and Co substitution.