Effect of sintering temperature on structural, optical and electrical relaxation properties of Gd-doped nickel-ferrites

Abstract

In this work, we report different structural, optical and electrical transport properties of Gd doped Ni-ferrites synthesized through citrate auto ignition method and sintered at different temperatures. The Rietveld refinement of X-ray diffraction patterns confirms the production of Ni-Fe phase with an additional orthorhombic phase GdFeO3. The photoluminescence (PL) spectra shows that PL intensity is higher for higher temperature sintered samples suggesting higher recombination rate of photo generated electron hole pairs. The electrical analysis shows that the conductivity increases with increasing sintering temperatures. The analysis of complex impedance spectra indicates enhanced grain boundary contribution for samples sintered at higher temperatures. Scaling behavior of complex modulus for all the samples at different measuring temperature confirms the validity of time temperature superposition principle (TTSP) and also non Debye type relaxation dynamics in this system. The dielectric loss tangent is found to be lowered significantly for higher sintering temperature.