Effect of two different sites substitution on structural and optical properties of Bi4V2O11−δ

Bi4−xPbxV2O11−δ and Bi4V2−xAlxO11−δ (0.1≤x≤0.4) are synthesized by the solid state reaction method to study the effect of two different substituents on the structural and optical properties. The Rietveld refinement results confirmed that Bi4−xPbxV2O11−δ (0.1≤x≤0.4) and Bi4V2−xAlxO11−δ up to x=0.1 exhibit monoclinic structure. Higher Al3+ substitutions lead to form orthorhombic structure. Al3+ substituted system shows low optical band gap values as compared to Pb2+ substituted system. In both the cases, the optical band gaps lie in semiconducting range.