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

Abstract A series of Ni-Zn ferrite nanoparticles with a nominal composition Ni 0.5 Zn 0.5 Dy x Fe 2- x O 4 ( 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 Dy 3+ substituted Ni-Zn ferrites exhibit typical spinel structure. Moreover, Dy 3+ 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 m 2 /g when x is 0.1, about five times higher than that of Ni 0.5 Zn 0.5 Fe 2 O 4 sample. With the increase of Dy 3+ content, all the values of M s , M r and H c increase first and then decrease, and they maximize to 67.801 emu/g ( M s ), 11.10 ( M r ) and 79.89 G ( H c ), improving about 28%, 208% and 92%, respectively, compared with those of Ni 0.5 Zn 0.5 Fe 2 O 4 , when calcined at 1073 K and x is 0.025. In addition, the heating rate of Dy-substituted samples are also enhanced markedly.