Effect of Particle Size on Hyperfine Fields in Cr‐Substituted Nano Co‐Zn Ferrite

Abstract

Nanoparticles of chromium‐substituted cobalt zinc ferrite CCZF (Cr_0.25Co_0.25Zn_0.5Fe₂O₄) were prepared using a chemical co‐precipitation technique. X‐ray diffraction studies of the prepared material show that the particle size lies in the nano range, with the smallest crystallite size being around 5 nm. Crystallite sizes are seen to increase with increase in the annealing temperature. Fe‐57 Mössbauer studies at room temperature show that the bulk samples are ferromagnetic with the additional presence of two quadrupole doublets. The Mössbauer spectrum for the smallest sized particles consists of only two doublets showing the samples to be in the superparamagnetic state. Mössbauer spectra of other nano samples show that superparamagnetic and ferromagnetic states coexist.

Keywords:

• chemical co‐precipitation
• Fe‐57 Mössbauer studies
• nano
• superparamagnetism

Acknowledgments

This work has been supported by the UGC‐DRS and COSIST schemes of the epartment of Physics, M.L. Sukhadia University, Udaipur. One of us (Ram Kripal Sharma) acknowledges financial support by CSIR.