A novel biological strategy for morphology control of PbWO4 crystals in tomato extract

PbWO4 crystals were readily synthesized by reacting lead oxide (PbO2) with sodium tungstate (Na2WO4·2H2O) at room temperature in the presence of tomato extract. Biomolecules such as vitamins, proteins in the extract played both the roles of reductant and template. The size and morphology of the PbWO4 crystals could be controlled by adjusting the concentration of the reactants. When the concentration ratio of PbO2 and Na2WO4 was increased, the morphologies of the products varied from spherical to fusiform. Room-temperature fluorescence spectra indicated the products had a slight blue shift compared to the solid structure, which may be due to the structure defects in the crystals. The possible mechanism of PbWO4 crystal growth in tomato extract was discussed.