Structure analysis and electronic properties of ATe4+0.5Te6+1.5-xM6+xO6 (A=Rb, Cs, M6+=Mo, W) solid solutions with β-pyrochlore structure

Solid solutions CsTe_0.5⁴⁺(Te_1.5-x⁶⁺Mo_x)O₆ (x = 0.875-1.06), RbTe_0.5⁴⁺(Te_1.5-x⁶⁺Mo_x)O₆ (x = 0.5-0.75), CsTe_0.5⁴⁺(Te_1.5-x⁶⁺W_x)O₆ (x = 0.13-0.55) and RbTe_0.5⁴⁺(Te_1.5-x⁶⁺W_x)O₆ (x = 0.25-0.63) with cubic β-pyrochlore structure have been synthesized by solid-state reaction. The elemental composition was confirmed by X-ray microanalysis. The crystal structure changings in the area (Cs, Rb)Te_0.5⁴⁺(Te_1.5-x⁶⁺M_x)O₆ at x = 0-1.5 were investigated, and more suitable structure model of β-pyrochlore have been presented. The relative positions of valence band and conduction band edges were determined by UV-vis transmittance spectra and X-ray photoelectron spectroscopy analysis for β-pyrochlores CsTeMoO₆, RbTe_1·25Mo_0·75O₆, CsTe_1·625W_0·375O₆ and RbTe_1·5W_0·5O₆. So, they can be applied as visible-light-responsive photocatalysts for the decomposition of organic pollutants, dye molecules and water with producing hydrogen.