The effect of reaction temperature on crystallite size and magnetic properties of Zn0.4Mn0.6Fe2O4 oxide

Full text: Zn0.4Mn0.4Fe2O4 nanoparticles have been synthesized by glycol thermal reaction at different reaction temperatures. The effect of the reaction temperature and pressure on crystal size and magnetic properties is investigated. The grain size varies between 5 nm and 45 nm. The magnetic properties have been investigated by SQUID and Moessbauer measurements. The variation of Moessbauer spectra as a function of grain size is reported. Broad lines in the spectra for fine powders change to well resolved magnetic splitting with increasing grain size. Our results indicate transformation from single to multidomain behaviour in samples with particles larger than 20 nm. The variation of the magnetic parameters such as coercive fields, saturation magnetization as a function of grain size and temperature is also presented. The results indicate that the differences observed in the magnetic properties of the samples prepared by different methods are not only due to the difference in particle size but also due to the difference cation distribution in tetrahedral (A) and octahedral (B) sites. (author)