Synthesis and Structural Characterization of Nano-sized Copper Tungstate Particles

The nano-sized copper tungstate (CuWO4) was prepared by precipitation method in the presence of non-ionic copolymer surfactant (polyoxyethylene-polyoxypropylene block copolymer) and consequent annealing at low temperature (400 °C). The scanning electron microscopy (SEM) indicated formation of spherical CuWO4 particles in the size range from 10 to 90 nm. The thermogravimetric analysis was used to study dehydration processes. The X-ray diffraction analysis undoubtedly confirmed formation of triclinic CuWO4 and the refinement of the diffraction data showed that CuWO4 powder belongs to the distorted tungstate type of structure with space group P1-. The structure of the CuWO4 can be described as infinite zigzag chains formed by edge-sharing alternating [W-O6] and [Cu-O6] octahedra. Indirect and direct band-gap energies of CuWO4 (2.3 and 3.5 eV, respectively) were determined using optical measurements.