LnCrTeO6 (Ln= La, Pr, Nd) octahedral distortions and optical characterization

Abstract

LnCrTeO6 (La, Pr, Nd) compounds are suspected to appear as vibrant blue-green colored materials. LnCrTeO6 (La, Pr, Nd) were synthesized to analyze the local coordination environments of Ln3+, Cr3+, and Te6+ cations. Structural characterization was performed using X-ray diffraction (XRD) and optical properties were examined using diffuse reflectance spectroscopy (DRS). DRS data was further processed using the Kubelka-Munk function and a Tauc plot was generated to determine the direct and indirect band gap of these semiconducting materials. The superstructure peak corresponding to the (101) plane displayed relatively weak intensities in all samples and decreased in intensity from La to Nd. The (002) and (100) peak intensities varied across the samples. All cation octahedra displayed distorted bond lengths and angles. In each sample, the Cr–O bond lengths were atypical of Cr (III) bond lengths; values were closer to Cr(IV)–O bond distances, suggesting, the possible presence of Cr(IV) in LnCrTeO6 (La, Pr, Nd).