Characterization and low-temperature sintering of Ni0.5Zn0.5Fe2O4 nano-powders prepared by refluxing method

The as-prepared Ni_0.5Zn_0.5Fe₂O₄ powders fabricated directly from the solution of metal nitrates by the refluxing method were testified by the analysis of XRD, TEM, SAED and HRTEM. XRD pattern indicated that obtained Ni_0.5Zn_0.5Fe₂O₄ powders were single phase with spinel structure, TEM analysis showed that the powders with cubic shape were uniform in particle size of about 10-20 nm. Ceramics prepared by the as-synthesized Ni_0.5Zn_0.5Fe₂O₄ powders sintered at various temperatures between 950 °C and 1150 °C for 2 h were observed by SEM technique, which indicated that the Ni_0.5Zn_0.5Fe₂O₄ ferrites can almost be sintered to theoretic density at 1100 °C for 2 h, lower by at least about 200 °C compared with those ferrites prepared by the conventional oxide method. The relative magnetic loss tanδ/μ_i of the ceramic samples sintered at the temperature 1050 °C was measured to be of the order of 10^− 4-10^− 5 in the frequency range from 1 MHz to 10 MHz, and the threshold frequency of the ferrites was 77.2 MHz.