Research On Controllable Synthesis And Photoluminescent Properties Of Aluminates Phosphors

The aim of this dissertation is to prepare a series of aluminates phosphors by adjusting the experimental parameters of hydrothermal route. The relationships between shape/size of phosphors and photoluminescent properties were investigated. The major contents can be summarized as follows:1. Controllable Synthesis and Photoluminescence of ZnAl2O4:Eu3+ Phosphors:â‘ Ultrafine gahnite (ZnAl2O4) nanoparticles were successfully synthesized without post-annealing by varying the reaction parameters of hydrothermal route, including reaction temperature, reaction time and basic source. The experimental results revealed that urea as the basic source greatly benefits the formation of cubic ZnAl2O4 under hydrothermal conditions.â‘¡Spherical ZnAl2O4:Eu3+ phosphors were prepared via a simple PEG-assisted hydrothermal route.â‘¢Rod-like ZnAl2O4:Eu3+ phosphors were synthesized using 1-D NH4Al(OH)2CO3 nanowires as the sacrificial templates.â‘£Hollow ZnAl2O4:Eu3+ phosphors were prepared by using carbon nanospheres as hard templates. The experimental results revealed that the surface area of ZnAl2O4:Eu3+ phosphors can affect photoluminescent properties remarkablely.2. Controllable Synthesis and Photoluminescence of MgAl2O4:Eu3+ Phosphors:â‘ Spherical and rod-like MgAl2O4:Eu3+ phosphors were synthesized by hydrothermal route followed by post-annealing approach using urea as the basic source.â‘¡MgAl2O4:Eu3+ nanoplates and nanoparticles were prepared by hydrothermal route followed by post-annealing approach using hexamethylenetetramine (abbr. HMTA) as the basic source. The MgAl2O4:Eu3+ nanoplates having the most intense emission peak indicate that the nanoplate structures are in favor of luminescence of MgAl2O4:Eu3+ phosphors, and the possible reason was also studied.3. Controllable Synthesis and Photoluminescence of MAl2O4:Eu2+, Dy3+(M=Sr, Ca, Ba) Phosphors:A series of long afterlow materials, including SrAl2O4:Eu2+, Dy3+, CaAl2O4:Eu2+, Dy3+ and BaAl2O4:Eu2+, Dy3+, were prepared by hydrothermal route followed by post-annealing approach using urea as the basic source. To investigate photoluminescent properties of aluminate phosphors, the excitation and emission spectra and afterglow decay curves were measured at room temperature. In terms of the emission spectra, it is found MAl2O4:Eu2+, Dy3+(M=Sr, Ca, Ba) long afterlow materials have the strong emissions at 512nm,440nm and 495nm, respectively. By studying on the afterglow decay curves, it is seen that all the afterglow decay curves are composed of two regimes which are the initial rapid-decaying process and the subsequent slow-decaying process. Meanwhile, the order of afterglow intensity and decay time of phosphors is SrAl2O4:Eu2+, Dy3+>CaAl2O4:Eu2+, Dy3+>BaAl2O4:Eu2+, Dy3+. At last, the afterglow mechanism was also illustrated.