Abstract

Monodispersed, uniform, and hierarchical calcium tungstate (CaWO₄) microsphere structures were synthesized through a template-free hydrothermal synthesis using calcium chloride (CaCl₂) and sodium tungstate dihydrate (Na₂WO₄•2H₂O) as precursors, sodium phosphate dodecahydrate (Na₃PO₄•12H₂O) was used as structure-directing agent. The obtained samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A possible formation mechanism of the spherical CaWO₄ was proposed based on the experimental results. In addition, the fluorescence properties of the CaWO₄ were studied. Experiment results indicated that the obtained CaWO₄ microspheres were assembled by nanoparticles of 30-100 nm in diameter, PO₄ ^3- played a crucial role in the self-assembly process of the hierarchical structure. Moreover, CaWO₄ microspheres showed good fluorescence performance.

Keywords: CaWO₄, fluorescence property, hierarchical structure, hydrothermal method, microspheres.

Graphical Abstract