Hydrothermal synthesis of PbWO4 uniform hierarchical microspheres

In this work, hierarchical PbWO4 spheres assembled by nanorods were successfully synthesized through a tri-potassium citrate assisted hydrothermal process. The samples were studied by powder X-ray diffraction pattern (XRD), field scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It was found that citrate played a key role on the morphology of PbWO4 products. By adjusting concentration of citrate, PbWO4 octahedrons, hierarchical spheres, hierarchical ellipses could be obtained. Based on time-dependent experiments, we found the growth of the hierarchical spheres followed a self-assembly process. The most interesting part was that the hierarchical spheres/ellipses showed a blue emission peak at 440 nm, which differs from the typical green one at 500 nm as reported.