Hydrothermal Synthesis and Multicolor Upconversion Fluorescence of Novel LiLuF4:Yb3+,Tm3+ Microcrystals

LiLuF4:Yb3+, Tm3+ upconversion luminescence materials were synthesized by a hydrothermal method, in which NaF and NaBF4 were used as fluorine sources (labeled as sample A and B, respectively). Their morphologies, XRD patterns and UC emission properties were compared. The synthesized crystallites consist of regular octahedrons of several micrometers and aggregates. The XRD patterns indicate that they belong to tetragonal crystal system with I41/a space group. These microcrystals emit strong UC violet, visible and near infrared light under the excitation of 980 nm laser diode. The multicolor UC emissions from sample B are much stronger than those from sample A. The strong emission intensity is ascribed to good crystal quality of sample B.