Shape-controlled of CaWO4 microcrystals by self-assembly of nanocrystals via a simple sonochemical method

In this paper, we report the obtention of CaWO4 crystals with controlled morphologies, such as spindle-like, nanorods, urchin-like, and sphere-like, were selectively synthesized via a simple sonochemical method without any surfactants or templates. The as-prepared samples were characterized by X-ray diffraction, transmission electron microscopy and high-resolution transmission electron microscopy. It is found that the ultrasonic time and pH value played an important role in the morphology-controlled synthesis of CaWO4 crystals. The possible mechanism for the formation of CaWO4 samples with different shapes was discussed in detail.