A novel ionic-protonic conductor compound based on tellurium: Synthesis, crystal structure, thermal behavior, Hirshfeld surface analysis, electric and vibrational properties

In the current research work, we investigated the growth of the new potassium arsenate tellurate material formulated as K3(HAsO4)(H2AsO4).Te(OH)6(KAsTe) through the use of the hydrothermal preparation method. The KAsTe compound was crystallized in the monoclinic system with centrosymmetric space group C2/c. Within this structure, two types of polyhedra (TeO6 and HAsO4) were observed in the presence of K+cations. The stability and the cohesion of the crystal structure were ensured by the linkage of different polyhedra via O-H center dot center dot center dot O hydrogen bonds. To locate the closest contacts within this crystal structure, Hirshfeld surface analysis was performed. In fact, according to the fingerprint plots, we inferred that the hydrogen bonds constitute the dominant interactions present within this structure. The vibrational spectroscopy study at room temperature unveiled the occurrence and the independence of the ionic groups and provided detailed data on hydrogen bonds present in the crystal lattice. Thermal analyses (DSC, DTA, TG and MS) proved the presence of three phase transitions at 428, 510 and 553 K and indicated that no mass loss was recorded before 460 K. Furthermore, the sigma dc variation performed on KAsTe material suggested an important level of conductivity at high temperature, associated with the motion of H+ proton. This behavior goes in good agreement with the presence of the super-ionic protonic phase transition at 428 K.