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 °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.