Synthesis of Ce3+ substituted Ni-Co ferrites for high frequency and memory storage devices by sol-gel route

Abstract

Cerium (Ce3+) substituted Ni-Co ferrites with composition Ni0.3Co0.7CexFe2−xO4 (x = 0.0–0.20, with step size 0.05) were synthesized by sol-gel method. Face-centered cubic (FCC) spinel structure was revealed by X-ray analysis. The crystalline size was calculated ranging between 17.1 and 18.8 nm, lattice constant showed a decreasing trend with increase of Ce3+ contents, furthermore, X-ray density was calculated between 5.30 and 5.69 g/cm3. The two characteristic spinel ferrites absorption bands were seen around 550 (cm−1) and 415 (cm−1) in Fourier transform infra-red (FTIR) spectroscopy. The microstructural and elemental studies were carried out by field emission transmission electron microscopy (FE-TEM) and energy dispersive X-ray (EDX) respectively, the average particle size was calculated around 21.83 nm. Magnetic studies were per- formed by vibrating sample magnetometer (VSM), which showed that saturation magnetization Ms and remanence Mr decreased with substitution up to x = 0.10 due to small magnetic moment of Ce3+ than Fe3+. The coercivity Hc increased with substitution up to 908.93 Oe at x = 0.05, then it decreased following the trend of anisotropy constant. The dielectric studies exhibited decrease in dielectric parameters with fre- quency due to decreasing polarization in material. The dielectric loss was significantly decreased in material at high frequency. The Cole-Cole interpretation exhibited conduction mechanism being caused by grain boundary density. These attributes of Ce3+ substituted Ni-Co ferrites suggest their possible use in memory storage, switching and high frequency devices like antenna and satellite systems.