Phase transitions and vibrational study of (Cs3.5Rb0.5)[(Se0.85S0.15)O3]2[Te(OH)6]3 material

The ionic–protonic conductor (Cs3.5Rb0.5)[(Se0.85S0.15)O3]2[Te(OH)6]3 crystallizes in the orthorhombic system. The space group is Pccn. Three endothermic peaks in thermal behavior were detected for this compound at T1 = 400 K, T2 = 435 K and T3 = 480 K, by DSC experiment. These transitions analyzed by dielectric measurements using the impedance and modulus spectroscopy techniques. Raman spectra of the material recorded at various temperatures (300–600 K) in the frequency range 100–1100 cm−1 and IR spectra achieved at room temperature between 400 and 4000 cm−1, confirm the presence of all the phase transitions detected in the material and show that anionic groups coexist independently in the same crystal.