Surfactant Effect on Formation of CaWO₄:Eu³⁺ Crystals with Distinguished Morphologies in Hydrothermal Ambient

Abstract

Metal tungstates, expressed by the general formula of MWO4, have important properties and applications in photoluminescence, microwave applications, optical fibers, scintillator materials, humidity sensors, magnetic properties, and catalysts. In this paper, we report a successful synthesis of CaWO4:Eul+ crystals with various morphologies in mild hydrothermal conditions with surfacntant including sodium citrate, CTAB, PEG and citrate acid (CA). The formation of the crystals are strongly dependent on the employment of surfactant. The surfactant concentration has been found significant influence in the resulting morphologies due to different properties of each one. Extensive characterization have been performed by using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) in search of the formation mechanism of multi-morphological CaWO4:Eu3+ crystals. The growth mechanism of monodispersed CaWO4:EuS+ crystal are proposed. And the photoluminescence properties were investigated.

Enhanced photoluminescence of hollow CaWO4 microspheres: the fast fabrication, structural manipulation, and exploration of the growth mechanism

“…31,35 Knowledge about the synthetic strategies, morphology design and crystal phase manipulation of CaWO 4 materials facilitates the optimization of performance and eventually contributes to their industrial production. [36][37][38][39][40][41] Up to now, various methods have been employed to prepare CaWO 4 micro/nanomaterials, including the solid-state process, 40 co-precipitation, 20,31,42,43 hydrothermal synthesis, 21,29,44 microemulsion technique, 45,46 autoigniting combustion, 46 ball milling, 47 microwave irradiation method, 5,[48][49][50][51][52] etc. For example, E. Sinha et al fabricated CaWO 4 microparticles with an average size of B1 mm via a solid-state reaction route at 1200 1C for 3 h. 40 The strong green PL emission, observed in the as-prepared CaWO 4 microparticles at room temperature, was attributed to the intermediate level distortion occurring in the band gap caused by the symmetry breakage in the lattice.…”

K3Eu5(PO4)6: hydrothermal synthesis, crystal structure and photoluminescence properties

“…In recent years, inorganic solid-state functional crystalline materials have been widely used in solar-light conversion, optical fibers, humidity sensors, data storage, catalysis, scintillator, solid-state lasers and other fields (Chen et al, 2016;Bharat et al, 2017;Zhou et al, 2016;Wei et al, 2016;Lu et al, 2017). As one of the most popular materials, phosphors are of current interest and great importance due to their frequency converting ability and potential applications in white-light emitting diodes (W-LEDs).…”