AC Impedance Spectroscopy, Conductivity and Optical Studies of Sr doped Bismuth Ferrite Nanocomposites

摘要

Effect of Sr doping on the structural, optical, dielectric, impedance properties of citrate combustionreaction route prepared Bi1-xSrxFeO3 (BSFO) nanocomposite has been investigated. The study ofFourier Transform Infrared Spectroscopy confirms the formation of perovskite structure of the Srdoped bismuth ferrite samples. SEM analysis shows decrease in grain size with increasing Srconcentration in BSFO nanocomposite. UVisible absorption spectra in the spectral range 1.0.5 eVshowed two doubly degenerate d transitions and two charge transfer transitions and optical band gapis found to decrease from 2.14 to 2.05 eV with increasing Sr concentration. Studies of frequency andtemperature dependences of dielectric permittivity, impedance and electric modulus of the materials ino o broad frequency (20 Hz- 1 MHz) and temperature (30 C 500 C) ranges using a complex impedancespectroscopy technique have provided interesting information on the contribution of the microstructurein these parameters. It has been observed that dielectric constant and dielectric losses decreases as thedoping of Sr increased from x=0.1 to x=0.3 and attained a maximum value for BSFO (x = 0.1) sample.Impedance analysis indicates the presence of grain (bulk) and grain boundary resistive contributionswhich are found to increase with the increased Sr content. The ac conductivity of the samples is foundto be frequency and temperature dependent and also vary with extent of Sr doping in BFO. Chargetransport through short as well as long range conduction contributions has been indicated in differenttemperature regions of conductivity studies.