Magnetic, electrical and dielectric behaviour of Ni 0.8Zn 0.2Fe 2O 4 prepared through flash combustion technique

Abstract

Nickel–zinc ferrites of composition Ni 0.8Zn 0.2Fe 2O 4 were prepared by flash combustion technique and sintered at various sintering temperatures such as 1150°C, 1250°C and 1350°C. Magnetic properties like hysteresis parameters, saturation magnetisation and Curie temperature were studied. Electrical properties namely AC-resistivity as a function of frequency and DC-resistivity as a function of temperature were studied for ferrite samples sintered at various temperatures. Dielectric properties such as dielectric constant, ε′ and dielectric loss factor, tan δ were also studied for ferrite samples as a function of frequency. It is observed that Ni–Zn ferrites prepared by this method have AC-resistivity of the order 10 6–10 1 Ω cm for the frequency range from 1 kHz to 13 MHz and DC-resistivity of the order ⩾10 9 Ω cm is observed as the function of temperature from room temperature to 300°C. The resistivity obtained is higher than that of ferrites prepared by the conventional ceramic method. This is because of high purity, controlled microstructure and porosity of ferrites prepared by flash combustion technique. The dielectric constant and dielectric loss obtained for the ferrites prepared through this flash combustion technique possess lower value than that of the ferrites prepared by conventional ceramic method for the same composition. High resistivity and low dielectric behaviour make these ferrite materials useful in high frequency applications.