Synthesis and luminescent properties of CaCO3:Eu3+@SiO2 phosphors with core–shell structure

Integrating the processes of preparation of CaCO 3 :Eu 3+ and its surface-coating, core–shell structured CaCO 3 :Eu 3+ @SiO 2 phosphors with red emission were synthesized by the carbonation method and surface precipitation procedure using sodium silicate as silica source. The phase structure, thermal stability, morphology and luminescent property of the as-synthesized samples were characterized by X-ray diffraction, Fourier transform infrared spectrum, thermal analysis, field-emission scanning electron microscopy, transmission electron microscope and photoluminescence spectra. The experimental results show that Eu 3+ ions as the luminescence center are divided into two types: one is at the surface of the CaCO 3 and the other inhabits the site of Ca 2+ . For CaCO 3 :Eu 3+ @SiO 2 phosphors, the SiO 2 layers are continuously coated on the surface of CaCO 3 :Eu 3+ and show a typical core–shell structure. After coated with SiO 2 layer, the luminous intensity and the compatibility with the rubber matrix increase greatly. Additionally, the luminous intensity increases with the increasing of Eu 3+ ions concentration in CaCO 3 core and concentration quenching occurs when Eu 3+ ions concentration exceeds 7.0 mol%, while it is 5.0 mol% for CaCO 3 :Eu 3+ phosphors. Therefore, preparation of CaCO 3 :Eu 3+ @SiO 2 phosphors can not only simplify the experimental process through integrating the preparation of CaCO 3 :Eu 3+ and SiO 2 layer, but also effectively increase the luminous intensities of CaCO 3 :Eu 3+ phosphors. The as-obtained phosphors may have potential applications in the fields of optical materials and functional polymer composite materials, such as plastics and rubbers.