Effect of lanthanide and transition metal on the structure, magnetic, and electric properties of nickel ferrites

A series of nanocrystalline Ni 1− x Mn x Ce x Fe 2− x O 4 ( x = 0.0, 0.02, 0.04, 0.06, 0.08, and 0.1) were prepared using the citrate auto-combustion method. X-ray diffraction (XRD) indicates that the spinel materials formed in a cubic single phase up to the sample x = 0.02. The average crystallite size is reduced from 61 to 31 nm due to the suppression of grain growth upon cerium occupation at the octahedral site. The cubic spinel structure was confirmed by Fourier-transform infrared (FT-IR) analysis. Scanning electron microscope (SEM) showed agglomerated and rod-shaped structures at various concentrations. AC conductivity and dielectric properties were measured over a frequency range of 20 Hz to 8 MHz. The AC conductivity increases with an enhancement in frequency. The prepared materials have great potential for utilization in microwave devices. The magnetic parameters were estimated from the measured hysteresis loops at room temperature and 100 K using a vibrating sample magnetometer (VSM), which indicated that the samples were suitable for magnetic memory device applications.