A study of electronic and optical properties of NaBi(WO4)2: A disordered double tungstate crystal

Electronic band structure, total and partial density of states and optical properties of NaBi(WO4)2 (NBW) crystal have been calculated using the first principles full potential linearized augmented plane wave (FP-LAPW) method. The electronic structure thus obtained shows a strong hybridization of W d and O p orbitals giving rise to relatively broad bands which are similar to other scheelite tungstates. Structural parameters obtained from Rietveld refinement of X-ray powder diffraction pattern recorded for high quality NBW crystal were further optimized by WIEN2K. Calculations using the generalized gradient approximation (GGA) show that this material exhibits an indirect band gap of 3.2±0.1 eV. The value of band gap, refractive index and birefringence obtained from first principle calculations are found to be in reasonable agreement with our experimental data.