Synthesis of garnet structure compounds using aqueous sol-gel processing

The sol-gel method based on metal chelates in aqueous solvents has been developed to prepare different oxides having garnet crystal structure. This synthetic approach has been used to prepare rare-earth doped yttrium aluminum garnet Y3Al5O12:Ce, Y3Al5O12:Nd, Y3Al5O12:Ho, and Y3Al5O12:Er samples (YAG:Ln). The polycrystalline powders sintered at 1000 degreesC are formed as single-phase garnet materials. The formation of pure and neodymium-doped lanthanum aluminum garnets (La3Al5O12 (LAG), and La3Al5O12:Nd (LAG:Nd)) at the same synthesis conditions, however, does not proceed. A systematic study of sol-gel technique synthesized Y3Ga5O12 (YGG) is presented using six different complexing agents. These complexing agents were found to influence the characteristics of the end products, in particular the homogeneity. Finally, some specific features of sol-gel derived mixed-metal Y3ScxAl5-x-yGayO12 (0 less than or equal to x, y less than or equal to 5) (YSAGG) garnets are discussed in the present paper. The phase purity, composition and microstructural features in the polycrystalline samples were studied by XRD analysis, IR spectroscopy and scanning electron microscopy. (C) 2003 Published by Elsevier B.V.