Temperature and frequency dependent electrical properties of NiCuZn ferrite with CuO-rich grain boundary segregation

Polycrystalline Ni 0.9-y Cu y Zn 0.1 Fe 1.98 O 4-δ (y = 0, 0.1 and 0.2) powder was synthesized by conventional solid-state reaction method. X-ray diffraction analysis confirmed single phase cubic spinel phase formation in the calcined powders. An additional phase was observed predominantly after sintering of y = 0.2 compound. The extra phase in the sintered sample is due to the formation of CuO-rich segregation along the grain boundary, which is confirmed by high resolution scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy analysis. In order to understand the temperature and frequency dependent electrical properties of segregated ferrite, detailed impedance spectra was investigated on Ni 0.7 Cu 0.2 Zn 0.1 Fe 1.98 O 4-δ in the frequency range of 1 kHz-1 MHz and temperature range of 30-250 C. © 2014 Elsevier B.V. All rights reserved.