Thermal behavior and physicochemical studies of phase transitions before the decomposition in the Selenate Tellurate protonic conductor material

Abstract

Thermal analysis confirmed the presence of the phase transition at T= 320K in the Cs2SeO4.H6TeO6 (CsSeTe) material. The structural study carried out at T=360K shows that this compound passes from the monoclinic system with the space group P2_1/c at room temperature, to the trigonal system with the space group R3 ̅m. At room temperature, the anionic groups are well ordered and stable, whereas after the transition at T=320K, the selenate groups change their orientation and the tellurate polyhedra change their positions. The high temperature vibrational studies, carried out in a temperature range of 289 to 353 K, confirm the presence and nature of the transition detected by thermal analysis. The conductivity evolution versus temperature shows the presence of an ionic- protonic conduction phase transition at T=490K.