Optimisation and the Effect of Addition of Extra Bismuth on the Dielectric and Optical Properties of Bismuth Ferrite (BFO)

Abstract

Bi1+xFeO3 (BFO) crystallites with x = 0.00, 0.05 and 0.10 were prepared by sol gel route using molarity method stoichiometry control. Optimisation for the formation of pure phase sample was done by adding extra bismuth to compensate the bismuth loss during synthesis. XRD studies confirm the pure phase formation for 5% (0.05) Bi added leached BFO sample. FTIR studies revealed the presence of stretching and bending vibrations of the various bonds present in the samples. Dielectric response of 0.00, 0.05 (leached), and 0.10 Bi added BFO samples were studied as a function of frequency in the range 20 Hz – 2 MHz. With the increase in the concentration of Bi the dielectric constant showed a decreasing trend. The plot of tanδ with frequency for all the samples follows the same behaviour as the dielectric constant. The energy band gap was calculated by studying the optical absorbance spectra of all the samples. The energy band gap values of all the samples were found to be in the range of that of semiconductor making it suitable for photocatalysis and photovoltaic applications. All the mechanisms contributing to the above results and the various possible ways on how to improve the ferroelectric and optical properties of the pure phase BFO were being discussed.