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) Å, β=107.646(8)°, V=1451.7(3) Å3 and Z=4. La2Ba(Te3O8)(TeO3)2 features a 3D network structure in which the cationic [La2Ba(TeO3)2]4+ layers are cross-linked by Te3O84− anions. Both band structure calculation by the DFT method and optical diffuse reflectance spectrum measurements indicate that La2Ba(Te3O8)(TeO3)2 is a wide band-gap semiconductor.