Synthesis and photoluminescence properties of Eu~(3+)-doped silica@coordination polymer core-shell structures and their calcinated silica@Gd_2O_3:Eu and hollow Gd_2O_3:Eu microsphere products

摘要

The conjugation of Eu~(3+)-doped coordination polymers constructed from Gd~(3+) and isophthalic acid (H_2IPA) with silica particles is investigated for the production of luminescent microspheres. A series of doping ratio-controlled silica@coordination polymer core-shell spheres is easily synthesized by altering the amounts of metal nodes used in the reactions, where the ratios of Gd~(3+) and Eu~(3+) are 10:0 (1a), 9:1 (1b), 8:2 (1c), 7:3 (1d), 5:5 (1e), and 0:10 (1f). The formation of monodisperse uniform core-shell structures is achieved throughout the entirety of a series. Investigations of the photoluminescence property of the resulting series of silica@coordination polymer core-shell spheres reveal that 20% Eu ~(3+)-doped product (1c) has the strongest emission intensity. The subsequent calcination process on the silica@coordination polymer core-shell structures (1a-f) results in the formation of a series of doping ratio-controlled silica@Gd_2O_3:Eu core-shell microspheres (2a-f) with uniform shell thickness. During the calcination step, the coordination polymers within silica@coordination polymer core-shells are transformed into metal oxides, resulting in silica@Gd_2O _3:Eu core-shell structures. The final etching process on the silica@Gd_2O_3:Eu core-shell microspheres (2a-f) produces a series of hollow Gd_2O_3:Eu microspheres (3a-f) as a result of the elimination of silica cores. The luminescence intensities of silica@Gd_2O_3:Eu core-shell (2a-f) and hollow Gd _2O_3:Eu microspheres (3a-f) also vary depending upon the doping ratio of Eu~(3+) ions. A series of monodisperse Eu ~(3+)-doped luminescent silica@coordination polymer core-shell microspheres is synthesized through the growth of coordination polymers on silica surfaces. The doping ratio is controlled by altering the amounts of metal ions used in the reactions. The subsequent calcination and etching processes result in the formation of doping ratio-controlled luminescent silica@Gd _2O_3:Eu core-shell and hollow Gd_2O _3:Eu microspheres.