Enhanced Magnetic Properties of Zn Substituted Mg Ferrite

A study of the magnetic properties of nanoparticulate powders of ${\rm Mg}_{0.6}{\rm Zn}_{0.4}{\rm Fe}_{2}{\rm O}_{4}$ mixed ferrites prepared by a combustion reaction method is presented. Measurements of the magnetization $(M)$ and of the $ac$ magnetic susceptibility $(\chi _{\rm ac})$ were carried out for temperature $(T)$ and applied magnetic fields $(H)$ in the ranges of 2–300 K and $\pm$ 85 kOe, respectively. The coercive field $H_{c}$ was found to be nearly T-independent (11.6–13.7 Oe) cooling the sample from 300 to 2 K. The remanence $M_{r}$ and the magnetization at the highest applied field $M(H=85 {\rm kOe})$ were found to increase from 1.6 to 4.5 emu/g and from 58.5 to 105.0 emu/g, respectively, for temperatures in the same range. The values of $M(H=85 {\rm kOe})$ , $H_{c}$ and $M_{r}$ were found to be highly enhanced relative to nondoped samples and samples with higher average particle size.