Sol-gel synthesis, characterization and study of substitution effects in different gallium-containing garnets

Gallium-containing garnets (gadolinium gallium Gd3Ga5O12; GGG, and gadolinium scandium gallium Gd3Sc2Ga3O12; GSGG) were prepared using an aqueous sol-gel synthesis route. Different starting materials and TRIS (tris-(hydroxymethyl)-aminomethane), NH2C(CH2OH)(3) and 1,2-ethandiol as complexing agents were used in the sol-gel processing. The final products were obtained after the heating of the precursor gels at 1000 A degrees C for 10 h. The substitution effects of Fe3+, Ce3+, and Ce3+/Cr3+ in gallium garnets have been also investigated. The results obtained in this study have demonstrated that the formation of mixed-metal gallium garnets depends on the sol-gel synthesis parameters and nature of dopant element. The luminescent properties of GGG:Fe3+ specimens were identical to those of GSGG:Fe3+, showing the great iron quenching effect. The luminescence at 720-780 nm for the cerium-/chromium-co-doped GGG:Ce3+, Cr3+ phosphors was observed. The highest emission intensity for GGG:Ce3+, Cr3+ samples containing 3 mol% of dopants (1.5 mol% Ce and 1.5 mol% Cr) was determined. Cerium/chromium concentration-dependent luminescence spectra of doped GGG:Ce3+, Cr3+ samples. PL excitation spectrum (lambda (em) = 730 nm) of pure GGG is presented at left. Emission spectra (lambda (ex) = 460 nm) of GGG:Ce3+, Cr3+ as a function of Ce3+ and Cr3+ concentration are presented at right. [GRAPHICS] .