SYNTHESIS OF CaWO4 AND CaWO4:Eu MICROSPHERES BY PRECIPITATION

Abstract

Nearly monodisperse CaWO 4 and CaWO 4: Eu 3+ microspheres have been synthesized in large scale by a surfactant-assisted solution route, in which cetyltrimethyl ammonium bromide (CTAB) is used. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and photoluminescence (PL) were used to characterize the resulting samples. The results of XRD indicate that the CaWO 4 and CaWO 4: Eu 3+ samples have the scheelite structures. The growth process of these nearly monodisperse spheres with an average diameter around 3.2 μm has been examined. The results of FTIR indicate that CTAB plays an important role in the formation of microspheres. The CaWO 4 microspheres exhibit a blue emission band with a maximum at 423 nm. But the CaWO 4: Eu 3+ microspheres exhibit a red emission band with a maximum at 623 nm.