Synthesis And Photoluminescence Of Calcium Titanate Nanophosphors

Red emitting nanophosphors are one of key light-converting materials used in white LED.Being having a high physicochemical stability and excellent optical properties,Eu³⁺-doped CaTiO₃(Cal-xTiO3:xEu³⁺)is a promising red phosphor.In this thesis,the Ca_1-xTiO_3:xEu³⁺ nanophosphors were synthesized by chemical co-precipitation and solvothermal methods,the influences of synthesizing parameters,heat-treeing and Eu doping on the morphology,size and crystal structure of the Cai-xTiO3:xEu³⁺ phosphors were investigated,and the dependences of the photoluminescence performance on the size and Eu-doping content of Ca_1-xTiO_3:xEu³⁺ phosphors were analyzed and discussed.Ca_1-xTiO_3:xEu³⁺ cubic nanophosphors were successfully synthesized by chemical co-precipitation method combined with subsequently heat-treatment.The nanophosphors are single crystalline with particle size ranging from 27 to 135 nm.It was found the Ca_1-xTiO_3:xEu³⁺ nanophosphors can be obtained with sintering temperature as low as 400 ?.The Ca_1-xTiO_3:xEu³⁺ submicron-sized rectangle phosphors were synthesized by solvothermal method,and the Ca_1-xTiO_3:xEu³⁺ nanocubes were firstly fabricated by the solvothermal technique.The rectangle and nanocubes phosphors are all single crystalline,and it was found the addition of a small amount of water in the reaction system can substantially reduce the size of the nanocubes.An obvious narrow red emission band centered at 615 nm was observed under the excitation with 395 nm blue violet for the Ca_1-xTiO_3:xEu³⁺ nanoparticles,submicron-sized rectangle and nanocube phosphors.The PL intensity of the phosphors depends on not only the size,but also the Eu doping content of the Ca_1-xTiO_3:xEu³⁺ nanophosphors.A cubic-like crystal structure was observed because of the size effect in Ca_1-xTiO_3:xEu³⁺ phosphors,and it was found that Eu ions can simultaneously incorporate into Ca-and Ti-sites of CaTiO₃ crystal lattice.