Microwave sintering of iron deficient Ni–Cu–Zn ferrites for multilayer chip inductors

This study was aimed at the low temperature synthesis of iron deficient samples of Ni–Cu–Zn ferrite using the microwave sintering technique. The samples were sintered at 950 °C for 30 min. Microstuctural and structural analyses were carried out using a scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The lattice parameter was found to increase with increasing nickel concentration. The porosity calculated using X-ray density and measured density also shows a decreasing behavior with increasing nickel concentration. The variation of saturation magnetization was studied as a function of nickel concentration. All the compositions indicate that they are ferrimagnetic in nature. Initial permeability plotted against temperature at 10 kHz showed a sharp drop at Curie transition temperature and values observed at transition are found to be dependent on the nickel concentration. The dielectric constant, dielectric loss tangent and ac conductivity of all samples were measured at room temperature as a function of frequency. These parameters decrease with increase in frequency for all of the samples. The present ferrites are well suitable for the application in multilayer chip inductor due to its low temperature sinterability, good magnetic properties and low loss at high frequency.