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 electrical properties of KBFO has been investigated. Polycrystalline sample of KBFO is effectively prepared by citrate combustion method. Deriving out of Rietveld refinement of X-ray powder diffraction (XRD), KBFO conforms that, the sample is crystallized in monoclinic structure having P2/c space group. To know the surface morphology of the sample, scanning electron microscope (SEM) study is carried out. KBFO contains grains with different size in a micrometer range. Frequency dependent dielectric permittivity (ε′) of KBFO is investigated over a frequency range 100 Hz –1 MHz at some selected temperature and the data is well fitted with Modified Debye model. From the fitted results, KBFO manifests 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-1 MHz and 503 K- 603 K respectively. It is observed that ac conductivity shows an increasing order with increasing temperature. Jonscher′s power law is used to verify 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 process in KBFO follows correlated barrier hopping (CBH) model.