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

ABSTRACT

Polycrystalline samples of Bi substituted YMnO₃ belonging to the series Y_1-xBi_xMnO₃ (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 Y_0.5Bi_0.5MnO₃ 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.

KEYWORDS:

• Dielectric
• polaron
• conduction
• ferroelectric
• Cole-Cole
• relaxation mechanism

Acknowledgments

Authors acknowledge the Board of Research in Nuclear Studies for financial support vide Project No. 2011/34/7/BRNS/0596. MRA acknowledges the University Grants Commission, India for awarding the UGC-BSR Faculty Fellowship (Grant No. F.18-1/2011(BSR)).

Disclosure statement

No potential conflict of interest was reported by the authors.