Enhanced Dielectric Property of Ni Ferrite by Sm and Ho Substitution

The enhancement in the dielectric constant of NiO center dot Fe1.925Sm0.075O3 and NiO center dot Fe1.925Ho0.075O3 when compared to pure NiO center dot Fe2O3 is reported. Sm- and Ho-substituted Ni ferrites crystallize in the cubic inverse spinel phase. Frequency variation in the dielectric constant shows the dispersion that can be modeled with a modified Debye's function, which considers the possibility of more than one ion, contributing to the relaxation. Temperature-dependent electrical conductivity curves exhibit two distinct regions indicative of two different types of conduction mechanisms, the small polaron and variable range hopping, at 220-300 and 160-220 K regions, respectively. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3479553] All rights reserved.