Variation of structural and hyperfine parameters in nanoparticles of Cr-substituted Co-Zn ferrites

The effect of Cr substitution into nanocrystalline Co-Zn ferrite prepared by the chemical coprecipitation method has been studied. Mössbauer studies at a temperature (20 K) well below the blocking temperatures of the samples show that Cr goes preferentially into the octahedral B site and that the hyperfine fields at both A and B sites decrease with increase in Cr concentration. Based on the cation distribution obtained from fitting Mössbauer spectra, structural parameters such as lattice parameters, site bond and edge lengths, and the oxygen parameter u have been calculated. The trend of theoretically calculated lattice parameter with Cr content matches well with the experimentally obtained values.