Upconversion luminescence properties of different Fluoride matrix materials NaREF4 (RE: Gd, Lu, Y) doped with Er3+/Yb3+

The densities of state and optical properties of matrix materials were studied with the help of first-principles calculations. It is found that the absorption and reflectance of the NaGdF4 system in the infrared region were comparatively low. Such low values were beneficial to the reduction of the loss of excitation light. Furthermore, Er3+ and Yb3+ co-doped NaREF4 (RE: Gd, Lu, Y) were prepared by a simple hydrothermal method, which exhibited a regularly shaped hexagonal microrods. Under the excitation of 808 nm, 980 nm, 1064 nm and 1550 nm, three emission peaks were all observed at 521, 540 and 655 nm for these samples, and NaGdF4: Yb/Er has the highest fluorescence intensity among the three samples. Calculated and experimental results demonstrated that NaGdF4 is more suitable than the two other materials as a substrate for UC luminescence.