Structure, magnetic properties and atomic immigration of CoFe2O4 nanoparticles

CoFe2O4 nanoparticles have been prepared by sol-gel method. Mossbauer spectra at temperature varying from 80 to 873 K showed that the atomic site preference of nanoparticles is different from that of the bulk material. The results also showed that the T-c of nanosized CoFe2O4 is much lower than that of the bulk counterpart. This decrease of T-c in the nanoparticles may be attributed to the redistribution of Fe and Co cations at the A and B sites. The Mossbauer spectra also revealed that the hyperfine field varied with the temperature and the hyperfine interaction follows T-3/2 + T-5/2 law approximately. The average isomer shift decreases almost linearly with increasing temperature.