Co-precipitation synthesis of neodymium-doped yttrium aluminium oxides nanopowders: Quantitative phase investigation as a function of joint isothermal treatment conditions and neodymium content

Neodymium-doped yttrium aluminium nanopowders with nominal Nd:Y:Al ratio equal to X-.3-X-.5 (where X = 0, 0.006, 0.012, 0.024, 0.048, 0.081, 0.096, 0.171, 0.192, 0.384, 0.540 and 0.720) were prepared by the co-precipitation method and subjected to five cumulative stages of isothermal treatment in the temperature range from 900 to 1050 degrees C. The phase evolution of the oxides were investigated quantitatively by the X-ray powder diffraction approach using the Rietveld method of analysis. An almost single phase cubic garnet structure was attained at temperatures as low as 900 degrees C for specimens with neodymium loading less than ca. 6 at.% with respect to total (Nd + Y) atoms. Isothermal treatments of the powders up to 1050 degrees C remove the hexagonal YAlO3 metastable phase and maximize the amount of the garnet phase. However, for neodymium loading higher than ca. 6 at.%, the garnet structure remains substantially affected by the presence of monoclinic Y4Al2O9 and orthorhombic distorted perovskite-like YAlO3 phases. (c) 2006 Published by Elsevier B.V.