Structural and electrical properties of multiferroic YMnO_3 and YMn_(0.9)Cr_(0.06)Ni_(0.04)O_3

摘要

In the present work polycrystalline yttrium manganite YMnO_3 and YMn_(0.9)Cr_(0.06)Ni_(0.04)O_3 have been prepared by sol-gel auto combustion method. Investigations have been carried out on the structural and electrical properties of the prepared samples to study the effect of Cr~(3+) and Ni~(2+) ions substitution at Mn-site. The X-ray diffraction (XRD) pattern confirms the formation of single hexagonal phase for YMnO_3 and transition to orthorhombic phase with substitution. The crystallite size and grain size, as calculated from the Scherrer's formula and field effect scanning electron microscope (FESEM) respectively, are found to be larger in the substituted samples. The room temperature dielectric constant and dielectric loss as function of frequency from 100Hz to 1MHz have been studied. The result shows the usual dispersive nature of polycrystalline materials. AC conductivity of the samples are also studied and fitted with Jonscher's Universal power law. The results obtained are discussed.