Spectral-Luminescent Properties of Oxogermanate-Borates La 3 Gd 11 – x – y Yb x Er y Ge 2 B 6 O 34 Prepared by Coprecipitation

― A series of single-phase lanthanum-gadolinium germanate borates (LGGBs) La 3 Gd 11 ‒ x ‒ y Yb x Er y Ge 2 B 6 O 34 co-doped with Yb 3+ and Er 3+ ions, which are promising for the development of up-conversion phosphors in the visible range, has been prepared by coprecipitation followed by annealing of the intermediates. Morphology of the prepared LGGBs has been determined by SEM. The luminescence spectra of LGGBs under infrared (IR) laser excitation (λ = 974 nm) have been recorded, and the effect of the concentration of the sensitizer (Yb 3+ ) and luminescence activator (Er 3+ ) on the energy yield of up-conversion luminescence has been studied. The concentration of active ions in the composition of LGGBs has been monitored by inductively coupled plasma atomic emission spectroscopy (ICP AES). It is shown that the Yb 3+ /Er 3+ ratio optimal for obtaining the brightest phosphors is 7 : 3. The influence of the temperature of final annealing on the luminescent properties of the prepared LGGBs has been determined.