Title: Effect of annealing temperatures on the electrical conductivity and dielectric properties of Ni1.5Fe1.5O4 spinel ferrite prepared by chemical reaction at different pH values,
Abstract: The electrical conductivity and dielectric properties of Ni1.5Fe1.5O4 ferrite
has been controlled by varying the annealing temperature of the chemical routed
samples. The frequency activated conductivity obeyed Jonschers power law and
universal scaling suggested semiconductor nature. An unusual metal like state
has been revealed in the measurement temperature scale in between two
semiconductor states with different activation energy. The metal like state has
been affected by thermal annealing of the material. The analysis of electrical
impedance and modulus spectra has confirmed non-Debye dielectric relaxation
with contributions from grains and grain boundaries. The dielectric relaxation
process is thermally activated in terms of measurement temperature and
annealing temperature of the samples. The hole hopping process, due to presence
of Ni3+ ions in the present Ni rich ferrite, played a significant role in
determining the thermal activated conduction mechanism. This work has
successfully applied the technique of a combined variation of annealing
temperature and pH value during chemical reaction for tuning electrical
parameters in a wide range; for example dc limit of conductivity 10power(-4)
-10power(-12) S/cm, and unusually high activation energy 0.17-1.36 eV.