Facilely Direct Construction, White-Light Emission, and Color-Adjustable Luminescence of LaF₃:Pr³⁺@SiO₂ Yolk-Shell Nanospheres with Moisture Resistance

Poor water stability and single luminous color are the major drawbacks of the most phosphors reported. Therefore, it is important to realize multicolor luminescence in a phosphor with single host and single activator as well as moisture resistance. LaF3:Pr3+@SiO2 yolk-shell nanospheres are facilely obtained by a designing new technology of a simple and cost-effective electrospray ionization combined with a dicrucible fluorating technique without using protective gas. In addition, tunable photoluminescence, especially white-light emission, is successfully obtained in LaF3:Pr3+@SiO2 yolk-shell nanospheres by adjusting Pr3+ ion concentrations, and the luminescence mechanism of Pr3+ ion is advanced. Compared with the counterpart LaF3:Pr3+ nanospheres, the water stability of LaF3:Pr3+@SiO2 yolk-shell nanospheres is improved by 15% after immersion in water for 72 h, and the fluorescence intensity can be maintained at 86% of the initial intensity. Furthermore, by treating the yolk-shell nanospheres with hydrofluoric acid, it is not only demonstrated that the shell-layer is SiO2 but also core-LaF3:Pr3+ nanospheres are obtained. Particularly, only fluorination procedure among the halogenation can produce such special yolk-shell nanospheres, the formation mechanism of yolk-shell nanospheres is proposed detailedly based on the sound experiments and a corresponding new technology is built. These findings broaden practical applications of LaF3:Pr3+@SiO2 yolk-shell nanospheres.