Selective synthesis and shape-dependent photoluminescence properties of (Y0.95Eu0.05)2O3 submicron spheres and microplates

Red-emission (Y0.95Eu0.05)2O3 submicron spheres and microplates were selectively obtained via hydrothermal precursor synthesis (150 °C, 12 h) followed by calcination at 1000 °C. Characterizations of the products were carried out by combined means of XRD, FT-IR, FE-SEM and PL analysis. The precursors could be modulated from basic-carbonate submicron spheres to normal carbonate microplates by increasing the molar ratio of urea to Y+Eu from 10 to 40-100. The resultant oxides largely retain their respective precursor morphologies at 1000 °C, but morphology confined crystal growth was observed for the microplates, yielding more enhanced exposure of the (400) facets. Both the (Y0.95Eu0.05)2O3 spheres and microplates exhibit nearly identical positions of the PL bands and similar asymmetry factors of luminescence [I(5D0→7F2)/I(5D0→7F1), ∼11] under 250 nm excitation, but the microplates show a significantly strong red emission at ∼613 nm (∼1.33 times that of the spheres) owing to their larger particle size and denser packing of primary phosphor crystallites.