Synthesis of nanocrystalline Ni 0.5Zn 0.5Fe 2O 4 ferrite and study of its magnetic behavior at different temperatures

Abstract

Ni 0.5Zn 0.5Fe 2O 4 ferrite nanocrystals with average diameter in the range of 1–2 nm have been synthesized by reverse microemulsion. X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) are used to characterize the structural, morphological and magnetic properties. X-ray analysis showed that the nanocrystals possess cubic spinel structure. The absence of hysteresis, negligible remanence and coercivity at 300 K indicate the superparamagnetic character and single domain in the nanocrystalline Ni 0.5Zn 0.5Fe 2O 4 ferrite materials. The nanocrystalline Ni 0.5Zn 0.5Fe 2O 4 ferrite were annealed at 600 °C. As a result of heat treatment the average particle size increases from 2 nm to 5 nm and the corresponding magnetization values have increased to 21.69 emu/g at 300 K. However, at low temperature of 100 K, the annealed samples show hysteresis loop which is the characteristic of a superparamagnetic to ferromagnetic transition. In addition, a comparative study of the magnetic properties of Ni 0.5Zn 0.5Fe 2O 4 ferrite nanocrystals obtained from reverse microemulsion has been carried out with those obtained from the general chemical co-precipitation route.