Dielectric, optical and structural properties of Bi4V2−xSrxO11−δ (0.05≤x≤0.20)

Composition Bi4V2−xSrxO11−δ (0.05≤x≤0.20) is synthesized by melt quench technique followed by heat treatment at 800 °C for 12 h. These compounds are characterised by X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, UV-visible spectroscopy, impedance spectroscopy and scanning electron microscopy. X-ray diffraction patterns of all the samples show γ-phase stabilization at room temperature except x=0.05 heat treated sample. The optical band gap of all the samples is observed in semiconducting range. The lowest and the highest optical band gap is 2.39 eV and 2.57 eV for x=0.10 heat treated and x=0.20 quenched samples, respectively. The highest value of dielectric constant is obtained ~107 with very low dielectric loss for x=0.15 and 0.20 samples at ~350 °C and below 10 Hz. The grain size increases with dopant concentration leads to increase the dielectric constant.