title: Environmentally friendly aqueous solution synthesis of hierarchical CaWO4 microspheres at room temperature.
abstract: An environmentally friendly route for the synthesis of hierarchical CaWO4 microspheres with novel morphology at room temperature has been successfully developed. CaCl2 and Na2WO4 were used as reaction regents, and distilled water was used as an environmentally friendly solvent. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence spectroscopy. This green wet-chemical route provides a simple, one-step, low-cost approach for the large-scale synthesis of hierarchical CaWO4 microspheres with relatively uniform diameters of 3-6 microm. The hierarchical microspheres are built up with numerous nanorods with an average diameter of 50 nm, which are radially oriented to the microsphere center. SEM observations of different intermediates indicate the possible growth process, in which the hierarchical structure growth is from nuclei through kayak-like, rod-like, peanut-like, dumbbell-like, and peach-like structures to final microspheres, via "self-assembled preferential end growth" of kayak-like particles in aqueous solution. The hierarchical CaWO4 microspheres exhibit a strong, broad blue emission peak of 412 nm.
authors.affiliation: School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, PR China.
authors.forename: Wenshou
authors.initials: W
authors.lastname: Wang
authors.forename: Liang
authors.initials: L
authors.lastname: Zhen
authors.forename: Chengyan
authors.initials: C
authors.lastname: Xu
authors.forename: Baoyou
authors.initials: B
authors.lastname: Zhang
authors.forename: Wenzhu
authors.initials: W
authors.lastname: Shao