Structural characterization, atomic Hirshfeld surface analysis, thermal behavior, electric and vibrational studies of the new tellurate conductor material

Abstract

In the current research work, we investigated the growth of the new potassium arsenate tellurate material formulated as K₂(HAsO₄).Te(OH)₆ (KAsTe) through the use of the slow preparation method. The (KAsTe) compound crystallized in the monoclinic system with centrosymmetric space group  P2₁/c. Within this structure, two types of polyhedra (Te-O₆ 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…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 445, 514 and 555 K and indicated that no mass loss was recorded before 460 K. Furthermore, the σ_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 445 K.