Structural and optical properties of quenched and heat-treated Bi4V2−xMgxO11−δ (0.0≤x≤0.20)

Bi4V2−xMgxO11−δ (0.0≤x≤0.20) are synthesized by melt quench technique. The as quenched samples are heat treated at 800 °C for 12 h in air. These samples are characterized by different techniques for their structural and optical properties. The γ-phase is stabilized at low dopant concentration (Mg2+) than earlier reported values for the similar system. The heat-treated samples exhibit smaller grain size with porosity, as compared to quenched samples. Higher thermal expansion coefficients (TECs) are observed in heat-treated than quenched samples. The highest TEC is observed for x=0.15 sample, i.e. 9.7×10−6 K. Blue shift in FT-IR spectra is observed in heat treated samples as seen in Fourier Transform-Infra Red spectra (FT-IR). The lowest optical band gap is observed in heat-treated (x=0.0) sample, i.e. 2.27 eV.