Investigating Structural and Electronic Properties of KBiFe2O5 Multiferroic

Abstract

KBiFe2O5 (KBFO) is one of the oxygen deficient perovskites which specifically comes under brownmillerite family. In this work, structural and electronic properties of KBFO has been investigated. Polycrystalline sample of KBFO is effectively synthesized by citrate combustion method. From Rietveld refinement of x-ray powder diffraction (XRD), the sample is crystallized in monoclinic structure with P2/c space group. To know the surface morphology of the sample, field emission scanning electron microscope (FESEM) study is carried out. Grains of different size are present in sample in an irregular manner. Frequency dependent dielectric permittivity (ε′) of KBFO is investigated over a frequency range 100 Hz –1 MHz at room temperature and the data is well fitted with Modified Debye model. From the fitted results, KBFO shows non Debye type of relaxation. To explore the conduction mechanism, grain and grain boundary contribution of the sample, frequency dependent ac conductivity measurement is carried out at a frequency and temperature range 100 Hz-1MHz and 503 K- 603 K respectively. It is observed that ac conductivity increases with increasing temperature. Jonscher′s power law is used to fit the variation of ac conductivity with frequency graph. Based on the fitted parameters, it is found that the power exponent (n) decreases with increasing temperature which indicates the conduction mechanism of KBFO follows correlated barrier hopping (CBH) model.