Combined theoretical and experimental study of the electronic and optical property of Sb$_2$WO$_6$

Abstract

Both theoretical and experimental analysis are carried out to understand the physical properties of the fascinating electronic and optical properties of antimony tungstate (Sb$_2$WO$_6$). The nanosized ($\sim 40-80~nm$) material is produced using hydrothermal method followed by the SEM and XRD analysis to find the structural properties. The present calculations using PBEsol and PBE approximations for exchange-correlation potential are compared with the experimental structural parameters and in the case of the calculations using PBEsol approach the predicted crystal parameters and simulated XRD pattern are in excellent agreement with experimental results. The experimental absorption spectra measured in the ultraviolet-visible range give the bandgap of $2.42 ~eV$, while the most intense peak of photoluminescence spectra is found at $468nm~(2.65 ~eV)$. Using density functional theory (DFT) technique, the band structure and density of states for \swo~ are calculated and the calculated bandgap of $2.62 ~eV$ is in agreement with the experimental finding. From theoretical partial density of states calculations we identify that the bandgap is formed between the O$-2p_y$ orbitals bonded with Sb at valence band maxima and the W$-5d_{x^2-y^2}$ orbital at conduction band minima. The atomic level transitions responsible for the peaks of absorption spectra and photoluminescence spectra are identified as well by the means of DFT calculations. Following the matching of theoretical and experimental observations, the calculations of optical properties reveal the plasma frequency to be equal to $13.36 ~eV$.