Effects of HfO2 dopant on the structure, magnetic and electrical properties of NiZnCo ferrites

HfO2 doped NiZnCo bulk ferrites, Ni0.5Zn0.3Co0.2Fe2O4 with different HfO2 dopant content (0 ≤ x ≤ 0.1 wt%), were fabricated by the solid states reaction method. We investigated the influence of HfO2 doping on structure and electromagnetic properties. The XRD pattern shows that as the doping of HfO2 increases, the lattice parameter decreases and the X-ray density increases. There is an extra peak in each sample due to generation of NiCo2O4 impurity phase. The SEM images demonstrate the grain size slightly decreases with increasing HfO2 content. As the amount of HfO2 doping increases, the saturation magnetization increases linearly and the coercivity decreases. The polarization of all ferrite samples is due to the fact that the electronic hopping frequency between Fe2+ and Fe3+ ions can't keep up with external applied frequency. As the amount of HfO2 doping increases, the dielectric constant increases when x