Influence of B-site doping on structural, optical and dielectric properties of bismuth ferrite

Abstract

The present work discusses the nature of electrical defects that influence the dielectric response of BiFe1-xZrxO3 nanostructures fabricated by hydrothermal method for x = 0.0, 0.005, 0.01, 0.015, 0.02 and 0.025. X-ray diffraction studies reveal that a higher concentration of Zr4+ ions can lead to the formation of an impure phase like Bi2Fe4O9 which increases the leakage current. Besides, the suppression of E-modes in a 1.5% doped sample confirms the structural distortion in FeO6 octahedra. A decrease in the optical band gap of Zr-doped samples indicates the presence of oxygen vacancies as donor levels within the forbidden gap. The dielectric constant of a 1.5% doped sample is quite higher than pure BiFeO3 sample at a frequency below 1 kHz. However, at higher frequency region (>1 kHz) the difference in dielectric constant between 1.5% Zr doped and a pure sample is quite less. Further, the broadened peak of M“(ω) of the doped sample indicates the non-Debye relaxation of charge carriers with different time constants.