Nanostructured Yb:GGG polycrystalline powders via gel combustion method

Gadolinium gallium garnet (GGG) nanopowders doped with ytterbium ions (Yb:GGG) were synthesized with citric acid as a fuel via gel combustion method. The optimized conditions for preparing Yb3+:Gd3Ga5O12 nanopowders were discussed. The heat behavior, structure and morphology of powders were analyzed with thermal analysis (TG-DTA), X-ray diffraction (XRD), infrared spectra (IR) and transmission electron microscope (TEM). TG-DTA analysis revealed that the weight loss of the precursor occured below 800 °C and its crystallization temperature was 830.6 °C. XRD and IR analysis showed that the precursor converted directly into pure GGG at a relatively lower temperature (900 °C) without any other intermediate phase. The lattice constant was 1.2377 calculated by extrapolation method. TEM results indicated that the spherical powders showed good dispersity and had a relatively narrow size distribution with average particle size of approximately 40–50 nm, which was favorable for good sinterability of Yb:GGG laser ceramic.