Automated method for the determination of the band gap energy of pure and mixed powder samples using diffuse...

An automated method to determine the band gap energy (E ) of pure and mixed powder compounds using diffuse reflectance spectroscopy is presented. This method is based on a five-step algorithm that mimics the judgment made by an expert analyst in identifying the linear segments in Tauc plots and subsequent estimation of the E value. It is demonstrated that the method to estimate E by intersecting the straight-line fit of the Tauc segment with the photon energy axis is not appropriate for those samples containing more than one optical absorbing phase because systematic underestimation of the E value results. The automated method accounts for such cases by introducing a base line function. The robustness of the implemented algorithm was tested using three model systems, ZnO-Al₂O₃, ZnO-CoO and ZnO-CdO. The estimated E 's using the automated method differ in less than 1% than those obtained by its manual counterpart.