Role of site-specific Ho substitution on the structural, morphological, electrical and dielectric properties of BiFeO ₃

Multiferroics with compositions BiFeO3, Bi0.90Ho0.10FeO3 and BiFe0.90Ho0.10O3 have been successfully prepared by solid-state reaction method. The structural analysis of Ho-substituted BiFeO3 affirms that the compounds are crystallized under rhombohedral perovskite structure with space group R3¯c along with non-perovskite Bi2Fe4O9 phase. Cuboidal-shaped grains are observed in the micrographs of the Ho-substituted BiFeO3 sample with Ho at the Fe site. The changes in electrical and dielectric parameters with Ho substitution at the A-/B-site of BiFeO3 have a strong co-relation to its structural density, phase transformation and presence of Bi2Fe4O9 phase. These parameters are strongly dependent on the frequency, and its high values are obtained at low frequency because of the space charge polarization effect. The smaller values of impedance phase angles of BiFeO3, Bi0.90Ho0.10FeO3 and BiFe0.90Ho0.10O3 compounds compared to the anticipated 90∘ for an ideal capacitor show that these BFO-based compounds possess non-ideal capacitive/pseudocapacitive behavior.