Preparation of spherical core–shell structured SiO2@CaMoO4:Eu3+,Li+ red phosphors

• A novel approach has been attempted to prepare core-shell structured submicrospheres.
• The obtained SiO2@CaMoO4:Eu3+,Li+ submicrospheres were monodisperse and nonagglomeration.
• The phosphors showed strong red emission under near ultraviolet (UV) or blue light.

Uniform spherical core–shell structured SiO2@CaMoO4:Eu3+,Li+ phosphors were prepared by a combined homogeneous precipitation approach and combustion synthesis. CaMoO4:Eu3+,Li+ layer was grown onto submicrometer amorphous SiO2 particles, which were synthesized by the Stöber method, via a homogeneous precipitation technique. The following combustion reaction at 600 °C and simply post-annealing resulted in uniform spherical SiO2@CaMoO4:Eu3+,Li+ core–shell structured phosphors. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectra (EDS), and photoluminescence (PL). The results show that the amorphous SiO2 submicrospheres were coated by crystalline CaMoO4:Eu3+,Li+ nanoparticles, forming spherical core–shell structure with uniform size of ∼260 nm. The powder samples showed strong red emission corresponding to 5D0 → 7F2 transitions of Eu3+ ions under near ultraviolet (UV) or blue light. Their color coordinate (0.63, 0.36) is close to the standard of national television standards committee (NTSC) (0.67, 0.33).