Synthesis and characterization of new rocksalt superstructure type layered oxides Li4.5M0.5TeO6 (M(III) = Cr, Mn, Al, Ga)

Oxides of stoichiometry Li4.5M0.5TeO6 (M(III)= Cr, Mn, Al, Ga) have been synthesized by the solid state method and are characterized for the first time. The Rietveld refinements of the PXRD measurements confirmed the structure to be similar to the Li-3(Li1.5Fe0.5Te)O-6 (S.G. C2/m; a similar to 5.183 angstrom; b similar to 8.885 angstrom; c similar to 5.168 angstrom; beta similar to 110.6 degrees) oxide. The oxides undergo ion-exchange reactions with Ag+ ions. UV-vis diffuse reflectance measurements showed the variation in the band gaps in consistent with the colors observed from brown, brick red to white respectively for Cr3+, Mn3+ and Al3+ or Ga3+ containing oxides. The stabilization of Li(4.5)Ma(0.5)TeO(6) (M(III)= Cr, Mn, Al, Ga) obtained by varying the alkali metal (Li+) ions together with other M3+ ions and Te6+ ions forming the edge shared octahedral layer in the rocksalt ordered structures yet again shows the rich compositional versatility of AMO(2) type oxides. (C) 2015 Elsevier Ltd. All rights reserved.