Preparation And Encapsulation Of SrAl₂O₄:Eu²⁺, Dy³⁺ Long-lasting Afterglow Phosphors

Aluminate has lately become the most intensively studied and the most widely applied matrix for long afterglow phosphors.And strontium aluminate activated by rare earth ions,SrAl₂O₄:Eu²⁺,Dy³⁺,is the best green long afterglow phosphor. SrAl₂O₄:Eu²⁺,Dy³⁺ phosphor is more bright,long lasting,and non-radioactive relative to sulfide phosphor.However,commercial SrAl₂O₄:Eu²⁺,Dy³⁺ phosphor particles, which are usually produced by high-temperature solid reaction method,are too big and hard to pulverize.What's worse,if they are put into water or moist air,hydrolysis will soon occur.Therefore,to produce ultra-free particles and water endurant particles are the top objects in the studying of SrAl₂O₄:Eu²⁺,Dy³⁺ phosphors.This work mainly contained the preparation of nano SrAl₂O₄:Eu²⁺,Dy³⁺ phosphors and the encapsulation of commercial micro SrAl₂O₄:Eu²⁺,Dy³⁺ phosphors.In this dissertation,gelatin-templated method and hydrothermal co-precipitation method were performed to produce nano SrA1204:Eu²⁺,Dy³⁺ phosphors.And the effect of synthesis process on particle size,morphology,and luminescence of phosphors was studied simply.Results showed that ball-like SrAl₂O₄:Eu²⁺,Dy³⁺ phosphors with size of 10-20 nm could be produced by the gelatin-templated method. But the phosphor particles badly congregated,and their crystal phases were impure, and still their luminescence was weak.In contrast,well-dispersed whisker pure-phased SrAl₂O₄:Eu²⁺,Dy³⁺ phosphors with size of 20×1000 nm could be produced by the hydrothermal co-precipitation method.The luminescence of phosphors produced in this way was very excellent.Triethyl phosphate and phosphoric acid were first applied to surface treat commercial micro SrAl₂O₄:Eu²⁺,Dy³⁺ phosphors in this thesis.Experimental results indicated that compact and mean layers could form on the phosphors by the reactions between triethyl phosphate and phosphoric acid and strontium aluminate.The layers could endow this class of phosphors great water resistance,and the issue of hydrolysis was resolved completely.Furthermore,the luminescence of phosphors was enhanced to some degree.Antibacterial agents were introduced into the process of encapsulation using phosphoric acid and embedded in the coating layers.And composite materials with both long-lasting luminescence and antibacterial function were successfully fabricated.