On the conduction mechanism of bismuth substituted multiferroic yttrium manganite using dielectric spectroscopy

Abstract

ABSTRACT Polycrystalline samples of Bi substituted YMnO3 belonging to the series Y1-xBixMnO3 (x = 0, 0.3 and 0.5) were synthesised by employing a citrate gel method. X-ray diffraction confirmed the formation of a dominant phase of YMnO3 and scanning electron microscopy revealed grain growth. Temperature-dependent dielectric studies showed an increase in the dielectric response with temperature and also a change in the conduction mechanism with an increase in Bi percentage. The loss peaks obtained for Y0.5Bi0.5MnO3 samples indicate the existence of multiple relaxations. A cross over from polar hopping to a dipolar response is noticed which is a marked change in the conduction process. The Cole-Cole data also support such a phenomenon. Incorporation of Bi in YMnO3, a room temperature ferroelectric, transforms to a predominant orthorhombic structure aiding pronounced changes in the conduction process.