Synthesis and Luminescence Characteristics of LaF3:Yb:Er Powders Produced by Coprecipitation from Aqueous Solutions

Hydrated lanthanum fluoride powders, both undoped, and doped with erbium and ytterbium fluorides (to a total content of 6-28 mol %), of the general formula RF3 center dot nH(2)O (n = 0.30 +/- 0.01), crystallizing in the hexagonal system, were obtained by coprecipitation from aqueous solutions of the corresponding nitrates by the interaction with hydrofluoric acid. The dehydration is completed at 380A degrees C. At 600A degrees C, the concentrated solid solution decomposes to precipitate a phase with the structure of orthorhombic YF3. The efficiency of the upconversion luminescence of the powders, excited at a wavelength of 974 nm, is low.