Exploring the Corundum Structure as a Host for Colored Compounds – Synthesis, Structures, and Optical Studies of (MM′)3TeO6 (M = Mg, Mn, Co, Ni, Zn; M′ = Mg, Mn, Co, Ni, Cu)

Abstract

We describe the syntheses, crystal structures, and optical absorption studies of the transition‐metal‐substituted corundum‐related oxides (MM′)3TeO6 (M = Mg, Mn, Co, Ni, Zn; M′ = Mg, Mn, Co, Ni, Cu). The oxides are readily synthesized by the solid‐state reactions of stoichiometric mixtures of the constituent binaries at 750–860 °C. The Rietveld refinements of the crystal structures from the powder X‐ray diffraction (XRD) data show that the Mg/Mn/Ni/Co/ZnO6 octahedra are distorted. We have interpreted the unique colors and the optical absorption spectra of these materials in terms of the distorted coordination geometries of the Mg/Mn/Ni/Co/ZnO6 chromophores. We have also identified the role that metal‐to‐metal charge transfer (MMCT) from the partially filled transition‐metal 3d orbitals to the empty Mo 4d orbitals plays in the color changes. We believe that the study of these transition‐metal substituted corundum oxides suggests directions for the development of colored inorganic materials featuring distorted octahedra around the 3d transition‐metal ions, as they may be useful as pigments.