Structure, magnetic properties and atomic immigration of CoFe2O4 nanoparticles
CoFe2O4纳米颗粒的结构、磁性以及离子迁移

CoFe2O4 nanoparticles have been prepared by sol-gel method. M?ssbauer 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 Tc of nanosized CoFe2O4 is much lower than that of the bulk counterpart. This decrease of Tc in the nanoparticles may be attributed to the redistribution of Fe and Co cations at the A and B sites. The M?ssbauer spectra also revealed that the hyperfine field varied with the temperature and the hyperfine interaction follows T3/2+T5/2 law approximately. The average isomer shift decreases almost linearly with increasing temperature.