Electrical and dielectric investigation, thermal analysis and vibrational spectroscopic study on the new hydrogeno–arsenate tellurate conductor

Highlights: • Three phase transitions before the decomposition detected by Thermal study. • The variation of Raman spectra at high temperatures describes all phase transitions. • The conductivity evolution confirms that this material is an ionic– protonic conductor. The cesium hydrogeno–arsenate tellurate material (CsAsTe) was grown at room temperature by slow evaporation of aqueous solution, in order to determine the nature of all phases transitions as well as to specify the dielectric properties and electrical conduction mechanisms. The DTA, TG and the mass spectrometry analyses revealed that no mass loss was recorded before 425 K. The DSC thermogram demonstrates the presence of three phase transitions at 365 K, 379 K and 400 K. Raman spectra were performed at various temperatures so as to characterize the phase transitions. The dielectric and electrical properties were specified. In this process, the Nyquist plots (–Z″ versus Z) were well fitted to an equivalent circuit built up by a series combination of grain and grain boundary elements. Furthermore, the DC conductivity evolution unveils the presence of the ionic–protonic conduction phase transition. The AC electrical investigation discloses that the conduction is insured by the correlated barrier hopping (CBH) model. The variation of M″ versus frequency proves that the conduction mechanism is thermally activated.