ErF microcrystals controllably deposited in perfluoride glass for upconversion red emission.

To the best of our knowledge, this paper first reports ErF microcrystals controllably deposited in perfluoride glass using phase-separation engineering techniques. The sample exhibited strong upconversion red-light emission owing to the small distance between Er ions and low phonon energy (585 cm). The sample has a high red/green ratio of up to 18.6, which, to our knowledge, is the highest reported value in Er-doped fluoride glass ceramics. Furthermore, the sample has a long fluorescence lifetime (3.18 ms @660 nm), good color saturation (0.6255,0.3707), and good thermal stability ( =0.31 ). Therefore, this sample has the potential for application across multiple fields, such as color display, visible laser, and lighting.