Near infrared down-conversion luminescence of Ba$_{4}$Y$_{3}$F$_{17}$:Yb$^{3+}$:Eu$^{3+}$ nanoparticles under ultraviolet excitation

The single-phase solid solutions Ba$_{4}$Y$_{3}$F$_{17}$:Yb:Eu with fluorite-type structure were synthesized by co-precipitation from aqueous solution technique. The average particle size was approximately 100 nm without agglomeration. The sensitized down-conversion luminescence of Yb$^{3+}$ ions was observed under 296 nm excitation. The quantum yield of Yb$^{3+}$ luminescence was found to reach avalue of 0.4 % for samples with Eu/Yb ratios of 0.1/1.0 and 0.1/10.0.