Chemical, mechanical and dielectric properties after sintering of hydrothermal nickel–zinc ferrites

Abstract

NiZn ferrites microstructurally controlled were produced after sintering of hydrothermal nanopowders. Chemical microanalyses showed that the zinc-loss phenomenon did not occur significantly, and that the elements iron and nickel probably control the diffusion process in the initial stage of sintering. The hardness and the dielectric response of the sintered NiZn ferrites exhibited a greater dependence on the grain size than on the density of the samples. The variations of the static dielectric permittivity and the relaxation frequency with the sintering conditions were correlated with the microstructural parameters. Complex impedance spectroscopy showed materials with high dielectric response, attributed to electron hopping conduction mechanism, and revealed the presence of a single relaxation, occurring at the grain boundaries.