Pr3+/Yb3+ Co-Doped β-Phase NaYF4 Microprisms: Controlled Synthesis and Upconversion Luminescence

Pr3+/Yb3+ co-doped hexagonal NaYF4(beta-NaYF4) microprisms were synthesized by the hydrothermal method, and ethylenediaminetetraacetic acid (EDTA) was introduced to control the size of the microcrystal samples. Bright upconverted fluorescence emission was observed when the samples were excited with an infrared (IR) laser at 976.4 nm. The emission was found to originate from the transitions of P-3(0)-F-3(2), P-3(0)-H-3(6) or (1)G(4)-H-3(4), P-3(1)-H-3(6), P-3(0)-H-3(5), P-3(1)-H-3(5), and P-3(0)-H-3(4) of Pr3+ ions. Possible mechanisms for upconversion fluorescence and concentration dependence as well as the crystal structure and its formation of NaYF4:Yb3+/Pr3+ microprisms were explored and discussed based on the experimental observations.