Synthesis of orthorhombic and cubic PbF2 by hydrothermal method

Orthorhombic (α-) and cubic (β-) PbF2 have been successfully synthesized via a simple hydrothermal process at 200 °C for 8 h using Pb(C2H3O)2 and NH4F as the raw reaction materials. The crystal structure, morphology, and optical properties of the as-synthesized samples were characterized by X-ray powder diffraction, scanning electron microscopy, and photoluminescence spectroscopy. XRD and SEM results show that the uniform β-PbF2 microspheres and porous-microspheres with the average diameter about 3 and 5 μm, respectively, were synthesized assisting with citric acid and α-PbF2 microrods and microtubes with a diameter about 15 and 10 μm, respectively, were synthesized assisting with acetic acid. The reaction conditions influencing the synthesis of these PbF2 microstructures, such as reaction time, the amount of CTAB, and the molar ratio of F/Pb were investigated. On the basis of a series of observations, phenomenological elucidation of a mechanism for the growth of the β-PbF2 microspheres and multispheres has been presented. Room-temperature photoluminescence measurements indicated that the as-prepared α-PbF2 microrods exhibit a strong green emission.