Synthesis of KGd 2 F 7 :Yb:Er Luminophores by Co-Precipitation from Aqueous Solutions

Single-phase powders of a KGd 1.52 Yb 0.40 Er 0.08 F 7 solid solution with an average particle size of 350 nm are synthesized by co-precipitation from aqueous solutions with a different order of mixing reagents. Surface leaching processes of potassium are revealed and studied. The optimal temperature of thermal treatment (525 °C) is determined. It enables the achievement of the energy yield of erbium up-conversion luminescence of 1.30±0.02% at the excitation wavelength of 974 nm with a pump power density of 1 W/cm 2 .