Ho∶YbGG Polycrystal Powder Synthesized by Low Temperature Combustion Method and Its Luminescent Characteristics

Holmium doped ytterbium gallium garnet (Ho:YbGG) polycrystal powder was synthesized by low temperature combustion method using citric acid as combustion agent. The mole fraction of Ho3+ was 2%. The Ho:YbGG polycrystal powder was determined by X-ray diffraction analysis and SEM analysis. The results show that 900 is the optimum calcination temperature. The absorption spectrum of the sample shows that the absorption peaks of Ho3+ are centered at 536 nm and 645 nm, corresponding to 5I85F4 (5S2) and 5I85F5 level transitions, respectively. The strong absorption bands of Ho3+ are centered at 940 nm and 982 nm, corresponding to 2F5/22F7/2 level transition. The fluorescence spectra of the samples show that the strong emission band of Ho3+ is centered at 1 989 nm, corresponding to 5I75I8 level transition. The upconversion spectrum of the sample was tested and the corresponding conversion mechanism was analyzed. Ho:YbGG can emit strong green and red light under 980 nm LD excitation, which are corresponding to 5F4(5S2)5I8 and 5F55I8 level transitions of Ho3+.