Fascinating morphologies of lead tungstate nanostructures by chimie douce approach

Lead tungstate occurs in nature as tetragonal stolzite of scheelite (CaWO₄) type and monoclinic raspite. In this work, we report, the typical growth of snowflake-like tetragonal stolzite and bamboo-leaf-like monoclinic raspite nanocrystals of PbWO₄ via a simple aqueous precipitation method and a polyol (polyethylene glycol-200) mediated precipitation method at room temperature (27 °C). The synthesised PbWO₄ nanocrystals were characterised by XRD, SEM, EDAX and TGA–DTA. The UV-Vis absorption and photoluminescence studies of PbWO₄ nanocrystals in the two morphologies were performed. The nuclei of PbWO₄ nanocrystals in aqueous medium self-assemble in a tetragonal manner to form the snowflake-like crystals. In polyol medium, PbWO₄ nuclei preferentially grow by oriented attachment process to form the bamboo-leaf-like morphology. The specific morphology of the regularly assembled PbWO₄ nanocrystals in the two phases finds applications in nanoelectronics and photonics. Compared to other well-known scintillators, PbWO₄ is most attractive for high-energy physics applications, because of its high density, short decay time and high irradiation damage resistance.