Mixed-valent titanium tellurium oxides, Ti1-x Te x Te3O8+x (x = 0, 0.1, and 0.12): Hydrothermal synthesis, structure, and characterization

Highlights: • Mixed-valent titanium tellurium oxides were synthesized. • Hydrothermal reactions allowed the synthesis of these oxides at 230°C. • Synthesis of pure phases was achieved. • The materials cell parameters were increased by Te⁶⁺ cation. • Extensive characterization of the synthesized materials was investigated. Novel mixed-valent titanium tellurium oxides, Ti_1-xTe_xTe₃O_8+x (compound A, B, and C for x=0, 0.1, and 0.12) were synthesized from TiOSO₄·xH₂SO₄·xH₂O, TeO₂, and H₃BO₃ using hydrothermal reaction conditions. The crystal structures of the materials were confirmed and refined using single-crystal X-ray diffraction. The compounds have three-dimensional framework structures consisting of TiO₆ or Ti/TeO₆ octahedra and asymmetric TeO₄ polyhedral groups. The cell parameter of compound A, B, and C increased with the increase in the Ti – O bond distance in the TiO₆ octahedron and is attributed to the increase in the Te⁶⁺ cation doping level. Detailed characterizations of the prepared materials, including Infrared, UV–visible diffuse reflectance, Raman spectra, thermogravimetric analyses, out-of-center distortion, and dipole moment calculations were performed.