Nanostructured Yb：GGG polycrystalline powders via gel combustion method

Gadolinium gallium gamet （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 yb^3＋：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 OR） and transmission electron microscope （TEM）. TG-DTA analysis revealed that the weight loss of the precursor occured below 800 ℃ and its crystallization temperature was 830.6℃. XRD and IR analysis showed that the precursor converted directly into pure GGG at a relatively lower temperature （900 ℃） 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 ran, which was favorable for good sinterability of Yb：GGG laser ceramic.