The growth and crystallography of bismuth tri-iodide crystals grown by vapor transport

A single crystal of bismuth tri-iodide (BiI3) of dimensions 1.2 × 1.2 × 0.4 cm3 has been grown by physical vapor transport. The lattice parameters of the hexagonal crystal and its polycrystalline powder precursor were measured by X-ray diffraction (XRD) and were in agreement, indicating that the vapor phase growth and sublimation purification processing at temperatures below 330°C did not affect the stoichiometry. X-ray rocking measurements of the single crystal showed low angle boundaries of the order of 0.05°. In tests as gamma radiation detectors, the vapor grown crystals were unsatisfactory, but observations suggest that better performance may be achievable with purer bismuth tri-iodide material.