Crystal Structure and Photocatalytic Properties of the CsV_0.625Te_1.375O₆ Mixed‐Valence β‐Pyrochlore Compound

Abstract A new β‐pyrochlore compound with complex composition of Cs(V 3+ 0.0625 V 5+ 0.5625 Te 4+ 0.34375 Te 6+ 1.03125 )O 6 has been synthesized by a solid‐state reaction and characterized by single‐crystal X‐ray diffraction and thermal analysis. The compound possesses the typical cubic symmetry with space group , however some of the oxygen atoms shift from the special position 48 f to the general crystallographic positions 32 e , 96 g and 96 h . This shift is caused by complex B‐site composition with mixed‐valence vanadium and tellurium atoms, especially the presence of the large Te 4+ ion. The locations of the valence band and conduction band edges were determined experimentally under vacuum conditions by X‐ray photoelectron spectroscopy, UV‐visible and impedance spectroscopy and evaluated theoretically for water solutions. The photocatalytic ability of the compound under visible light irradiation was determined using the methylene blue decomposition process as an example. The nature of the active radical species and possible dye degradation pathway were suggested according to experimental data.