Synthesis, phase transition and semiconductor properties of bi-tetrabutylphosphonium hexachlorostannate

The single crystals of bi-tetrabutylphosphonium hexachlorostannate were grown by solvent evaporation method and characterized by X-ray powder diffraction, Raman spectroscopy, and optical study. The X-ray powder diffraction indicates that it was crystallized in the monoclinic system, with the C2/c space group. Besides, temperature-controlled X-ray diffraction shows that the [P(C4H9)4]2SnCl6 compound indicates the presence of two-phase transitions detected at 388 and 403 K. The evolution of Raman line shifts, “ν”, and the half-width “Δν”, versus temperature show some singularities associated with the transitions, suggesting the important role of the anionic parts ((SnCl6)2-). Besides, the results of the Raman study confirm the conclusion drawn from the X-ray powder diffraction measurements that the phase transitions are located near 388 K and 403 K. Furthermore, an optical absorption measurement confirms the semiconductor nature with a band gap equal to 3.46 eV.