Effects of Dy3+ substitution on the structural and magnetic properties of Ni0.5Zn0.5Fe2O4 nanoparticles prepared by a sol-gel self-combustion method

A series of Ni-Zn ferrite nanoparticles with a nominal composition Ni0.5Zn0.5DyxFe2-xO4 (x=0.000–0.100 with steps of 0.025) was prepared by a simple sol-gel self-combustion method. The effects of composition and calcined temperatures on their morphology, specific area, magnetic properties and radio frequency heating rate are studied. It is found that all the Dy3+ substituted Ni-Zn ferrites exhibit typical spinel structure. Moreover, Dy3+ substitution can notably reduce the average crystal size and enhance the specific area of Ni-Zn ferrite. The value of specific area reaches 29.25 m2/g when x is 0.1, about five times higher than that of Ni0.5Zn0.5Fe2O4 sample. With the increase of Dy3+ content, all the values of Ms, Mr and Hc increase first and then decrease, and they maximize to 67.801 emu/g (Ms), 11.10 (Mr) and 79.89 G (Hc), improving about 28%, 208% and 92%, respectively, compared with those of Ni0.5Zn0.5Fe2O4, when calcined at 1073 K and x is 0.025. In addition, the heating rate of Dy-substituted samples are also enhanced markedly.