General and facile synthesis, formation process, and luminescence properties of well-defined rare earth oxides hollow spheres

Uniform and well-defined Ln(2)O(3) (Ln = Gd and Lu) hollow spheres have been fabricated via a hard template directed method with 3-aminophenol-formaldehyde (AF) resin as a template. During the synthesis procedure, the core-shell structured AF@Ln(OH)CO3 precursor spheres are firstly obtained via a homogeneous precipitation method. The final Ln2O3 hollow spheres are synthesized by a subsequent calcination treatment, which inherit the uniformity, dispersity, and morphology of the precursors and exhibit a reduction in diameter. The crystal structure, morphology, and formation process of the hollow spherical products have been systematically studied. After incorporating the proper lanthanide activator ions such as Eu3+, Yb3+/Er3+, or Yb3+/Ho3+ ions into the Gd2O3 and Lu2O3 host spheres, the as-synthesized luminescent hollow spheres can exhibit the characteristic downshift and upconversion emissions from different activator ions. The LED devices fabricated by the Gd2O3: Eu3+ and Lu2O3:Eu3+ phosphors and LED chip can show dazzling red emission light, which directly proves that the as-obtained phosphors may have prospects in fields of optoelectronic devices. Furthermore, the facile and general strategy may pave a critical way for the preparation of the hollow spherical rare earth oxides with well-defined structure and eminent physicochemical properties.