Hydrothermal Synthesis and Luminescence Properties of Monodisperse Spherical CaF 2 and CaF 2 :Ln 3+ (Ln = Eu, Tb, Ce/Tb) Microcrystals

Abstract

Spherical CaF2 and CaF2:Ln3+ (Ln = Eu, Tb, Ce/Tb) with tunable particle size (about 2.5 µm) have been synthesized by one-step facile and effective hydrothermal method. The spherical structure was highly uniform and well-dispersed. It was found that reaction time, pH value, and reaction temperature have important effects on the controlled synthesis of spherical CaF2. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), photo-luminescence (PL) and luminescence decay curve. Under UV excitation, the CaF2:Eu3+ showed the red emission (5D0→7FJ = 0, 1, 2, 3) and the CaF2:Tb3+ presented the green emission (5D4→7FJ = 6, 5, 4, 3), respectively. Furthermore, Ce3+/Tb3+ co-doped CaF2 showed efficient energy transfer from Ce3+ to Tb3+, which presented strong green photo-luminescence of Tb3+. Due to excellent luminescent properties, the obtained samples can be used in many fields, such as light display systems, optoelectronic devices and biological imaging.