Effect of processing parameters on structural and morphological Y2O3 :Yb3+/Ho3+ powders characteristics

Abstract

Up-converting yttrium oxide powders doped with Yb3+ and co-doped with Ho3+ were synthesized through hydrothermal processing at 200 °C/3 h. Reverse precipitation of the starting nitrates mixture is performed with the help of ammonium hydrogen carbonate (AHC) solution up to pH 7 or pH 9 prior to hydrothermal treatment. Morphological features of the as-prepared (asp)powders and rare earth oxides obtained after powders additional annealing at 1100 oC (3 and 12 h)are discussed based on X-ray powder diffractometry (XRPD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Structural refinement confirmed generation of the cubic bixbyte-structure (S.G. Ia-3) with non-uniform accomodation of dopants at C2 and S6 cationic sites. SEM revealed that the particles have plate-like or rod-like morphology in dependence of hydrothermal processing (pH). Due to the fact that are composed from nanograins (30-100 nm) they demonstrate prominent green luminescence centered at 550 nm after been excited with the infrared laser source (λ=978 nm).