Synthesis, crystal and band structures, and optical properties of a new lanthanide-alkaline earth tellurium(IV) oxide:: La2Ba(Te3O8)(TeO3)2

A new quaternary lanthanide alkaline-earth tellurium(IV) oxide, La2Ba(Te3O8)(TeO3)(2), has been prepared by the solid-state reaction and structurally characterized. The compound crystallizes in monoclinic space group C2/c with a = 19.119(3), b = 5.9923(5), c = 13.2970(19) angstrom, 107.646(8)degrees, V = 1451.7(3) angstrom(3) and Z = 4. La2Ba(Te3O8)(TeO3)(2) features a 3D network structure in which the cationic [La2Ba(TeO3)2 layers are cross-linked by Te3O84- anions. Both band structure calculation by the DFT method and optical diffuse reflectance spectrum measurements indicate that LaBa(Te3O8)(TeO3)(2) is a wide band-gap semiconductor. (c) 2007 Elsevier Inc. All rights reserved.