Microwave-assisted synthesis of PbWO4 nano-powders via a citrate complex precursor and its photoluminescence

Nanocrystalline lead tungstate (PbWO4) powders, which have scheelite-type structure, were successfully synthesized at low temperatures using a modified citrate complex method assisted by microwave irradiation. The citrate complex precursors were heat-treated at temperatures from 300 to 600 °C for 3 h. Crystallization of the PbWO4 precursor was detected at 400 °C, and completed at 500 °C. Nanocrystalline PbWO4 powders heat-treated between 400 and 600 °C primarily showed spherical and disperse morphology. The average crystallite sizes of PbWO4 were between 17 and 28 nm at temperatures between 400 and 600 °C, showing a tendency to increase with the temperature. The PbWO4 powders prepared at 600 °C showed the strongest photoluminescent intensity, which was ascribed to the higher crystallinity and homogeneous particle morphology.