Transparent lutetium aluminum garnet sintered from carbonate coprecipitated powders

Pure phase lutetium aluminum garnet (LuAG) powders have been obtained by coprecipitation from a mixed solution of aluminum and lutetium nitrate using ammonium hydrogen carbonate (AHC) as precipitant, followed by calcination of the dried precipitates at 1000 degrees C. The use of AHC as the precipitator and reverse-strike precipitation method can effectively avoid the formation of gelatinous hydrate precursor at high CO32- -to -OH- mole ratio in the solution. This is pivotal for the control of chemical homogeneity within the particles as well as the agglomeration and size of the particles. X-ray diffraction (XRD) and TEM analysis showed that the synthesized powder was single-phase LuAG, with weakly-agglomerated fine spherical grains (20 nm average) and a relatively narrow grain size distribution. The powders could be easily sintered into transparent LuAG ceramic in H-2 atmosphere at 1850 degrees C. (C) 2005 Elsevier B.V. All rights reserved.