X-ray induced synthesis of beta tin (β-Sn)

The destabilization of molecular structures via hard X-rays has been previously utilized to synthesize novel compounds. Here we report that the monochromatic X-ray induced decomposition of tin(II) oxalate (SnC₂O₄) at ambient and 0.6 GPa pressures lead to the formation of beta tin (β-Sn). At 1 GPa, only the degradation of SnC₂O₄ crystal structure is observed without any indication of β-Sn at the end of irradiation. The maximum transformation yield is achieved at 0.6 GPa suggesting the critical role of intermolecular distance in X-ray induced synthesis of β-Sn. Moreover, a modified Avrami equation is utilized to describe the kinetics and geometry of structural synthesis at ambient and 0.6 GPa. The obtained results demonstrate that X-ray irradiation can induce photochemical synthetic pathways different from conventional methods (e.g., high pressure, temperature, stoichiometric mixing) and that high pressure (HP) can be considered a tool to control X-ray induced photochemistry.