Low-temperature synthesis, phonon and luminescence properties of Eu doped Y3Al5O12 (YAG) nanopowders

This contribution presents two simple and cost-effective routes for the low-temperature and large-scale production of pure and Eu-doped Y3Al5O12 (yttrium aluminum garnet YAG) nanopowders. The proposed methodologies combine a mechanically assisted metathesis reaction or coprecipitation from solution followed by crystallization of the obtained precursors from molten sodium nitrate/nitrite. Both procedures allow obtaining pure and/or doped YAG nanopowders at remarkably low temperatures, i.e. already at 350 degrees C although firing at 500 degrees C is needed in order to get single phase and fully crystalline materials. As-obtained samples were characterized by XRD, TEM, Raman, IR and luminescence methods. These methods showed that the mean crystallite size is near 23-31 and 51 nm, when crystallization is performed from the amorphous precursor obtained by a mechanically assisted metathesis reaction and coprecipitation, respectively. Raman and IR spectra indicated better crystallinity of the powders prepared at 500 degrees C. The emission study showed that the intensity ratio between hypersensitive D-5(0) -> F-7(2) and magnetic-dipole D-5(0) -> F-7(1) transitions of Eu3+ is significantly larger than expected for well-crystallized YAG. Origin of this behavior is discussed. (C) 2013 Elsevier B.V. All rights reserved.