title: Synthesis and upconversion luminescence properties of CaF2:Yb3+/Tm3+ microspheres.
abstract: CaF2:Yb3+/Tm3+ microspheres were synthesized by using a simple hydrothermal method. Their structures and morphologies were characterized by X-ray diffraction (XRD) and field-effective scanning electron microscopy (FESEM). The microspheres were formed from a large number of nanospheres with almost the same diameter after annealing. The growth mechanism of the microspheres was discussed. Strong ultraviolet (UV) and blue upconversion (UC) emission from the CaF2 microspheres was observed under 980 nm excitation. The enhancement of the UV UC emission was attributed to the size effect of the nanoscale particles.
authors.affiliation: State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, P. R. China.
authors.forename: Tao
authors.initials: T
authors.lastname: Jiang
authors.forename: Dan
authors.initials: D
authors.lastname: Zhao
authors.forename: Weiping
authors.initials: W
authors.lastname: Qin