Dielectric and magnetic properties of Nickel ferrite ceramics using crystalline powders derived from DL alanine fuel in sol-gel auto-combustion

Dielectric and magnetic properties of NiFe2O4 ceramics prepared with powders using DL-alanine fuel in the sol-gel auto combustion technique are studied. DL-alanine fuel yields crystalline as-burnt powders, and when used for ceramic processing yields varying microstructure at different sintering temperatures. The dielectric properties are influenced by the resulting microstructure and the magnetic properties show slight change in saturation magnetization Ms (~44 - 46 emu/g). The coercive fields, dielectric losses and dispersion are reduced considerably at higher sintering temperatures (1200-1300 °C). The influence of changing microstructure is analyzed through dielectric response, complex impedance analysis and electrical modulus spectroscopy in the frequency range (10−2-107 Hz) to understand the interactions from the grain and grain boundary phases. Sintering at 1200 °C, is found to be optimum, yields lower losses & reduced dielectric dispersion, and high resistivity (3.4×108 Ω cm).