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A sol-gel method based on in situ generation of mixed-metal chelates by complexing metal ions with ethane-1,2-diol in aqueous media has been elaborated to prepare lanthanide-ion containing garnets, Gd 3 Al 5 O 12 (GAG) and La 3 Al 5 O 12 (LAG). XRD patterns of the powders sintered at 1 000°C revealed the formation of monophasic GAG. However, LAG does not form under the same experimental conditions. The phase composition of the samples was characterised by IR spectroscopy. Microstructural features of the polycrystalline garnets were studied by SEM.Garnets, both natural and synthetic, form a wide range of compounds which are closely related by their structure and chemical and physical properties. Garnets containing transition and rare-earth metals have many important technological applications such as magnetic and phosphorescent materials employed in solid-state lasers and TV screens, computer memories and in many devices such as microwave optical elements 1-4 .Yttrium aluminium garnet (Y 3 Al 5 O 12 , YAG) with excellent structural and optical properties is one of the most popular garnets. Since the discovery of ruby laser, which is Cr-doped Al 2 O 3 , the search for new solid-state laser materials with diverse properties such as laser ability at new wavelengths, broad tunability in to the near infrared (NIR) region and high efficiency, has been an important task for material scientists. Rare-earth-doped YAG oxides are also widely used in cathode-ray tubes (projection TV sets), field

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Aluminum I 2100Syntheses and Characterization of Gd3Al5O12 and La3Al5O12 Garnets. -The title compounds are synthesized by aqueous sol-gel processes using Gd 2 O 3 , La 2 O 3 , Al(NO3)3, HOAc, and glycol as starting materials. The obtained powders are sintered in air at different temperatures for 10 h and characterized by powder XRD, IR spectroscopy, and SEM. Monophasic Gd3Al5O12 samples are obtained at lower sintering temperatures (900-1100°C) compared with the temperature required for the solid state synthesis (>1600°C). The heat treatment of La-Al-O precursor gel powders at the same temperature leads to the formation of 3LaAlO3:Al2O3 or LaAlO3:La2O3:2Al2O3 mixtures instead of the single La3Al5O12 garnet phase. The proposed aqueous sol-gel method is inexpensive and thus appropriate for the large-scale production of new ceramic materials. -(GARSKAITE, E.; DUBNIKOVA, N.; KATELNIKOVAS, A.; PINKAS, J.; KAREIVA*, A.; Collect. Czech. Chem. Commun. 72 (2007) 3, 321-333;