Microwave-assisted preparation of nearly monodisperse flower-like CaF2 microspheres

Nearly monodisperse flower-like CaF 2 microspheres with average diameter of 1.2 m m were successfully synthesized via a rapid microwave route using ethylenediaminetetraacetic acid disodium (Edta) as a complexing reagent. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and photolumines- cence (PL). The XRD results indicated that the as-prepared CaF 2 microspheres were of cubic phases and had good crystallinity and purity. The TEM and SEM results revealed that these flower-like CaF 2 microspheres had uniform morphologies and sizes and consisted of many nanosheets. It was found that both Edta and NaBF 4 had great influences on the formation of these flower-like microspheres. A possible formation mechanism was initially proposed. In addition, rare-earth ions such as Ce 3 þ or Tb 3 þ doped CaF 2 microspheres were also prepared similarly and their luminescent properties were characterized