Design,Synthesis,and Properties Of Visible Persistent Luminescence Materials

Currently,human society are facing a crisis of the exhaustion of traditional energy and the deterioration of ecological environment.Exploring a new generation of energy-saving and environmentally friendly materials is an effective way to solve these crises.Persistent luminescence(Pers L)is the phenomenon that materials can continue to emit light after ceasing the excitation.This material cannot only supply lighting in dark conditions and reduce energy consumption,but also has broad application prospects in stress detection,information anti-counterfeiting,and biological imaging.However,there are still some problems,such as single matrix of materials and being difficulty to be applied.Thus,developing novel Pers L materials which are safe and environmentally friendly is of great value in scientific research and practical applications.In this thesis,aiming at developing novel visible Pers L materials and realizing new applications in specific scenes,a series of visible Pers L phosphors LiTaO₃:Pr³⁺and blue Pers L phosphors Ca₁₂Al₁₄O₃₃:Eu²⁺,Nd³⁺were successfully synthesized through high temperature solid-state reaction method.The structure and Pers L properties of materials were systematically studied.By means of thermoluminescence(TL)analysis and theoretical calculations,the mechanism of Pers L was discussed.Finally,the potential applications were explored.The main research contents and results are as follows:(1)A series of color-tunable visible Pers L phosphors LiTaO₃:Pr³⁺were designed and prepared.The Pers L color can be modulated merely by changing the concentration of Pr³⁺,which attributed to the concentration quenching resulted from the cross-relaxation effect.Meanwhile,combined with the deduction and analysis of TL curves,it indicates that the continuous shallow traps(0.668-0.8 e V)are suitable for Pers L.Moreover,LiTaO₃:Pr³⁺also exhibits excellent photostimulated luminescence(PSL)performance owing to the presence of stable deep traps of 0.916 e V.Based on experimental data and theoretical calculations,a feasible Pers L mechanism model was proposed.Finally,a four-color quick response code(QR-code)and an arrow symbol used for dynamic anti-counterfeiting were developed.Our work is designed to promote the practical applications of Pers L materials in information security areas.(2)A series of blue Pers L materials Ca₁₂Al₁₄O₃₃:Eu²⁺,Nd³⁺were designed and synthesized.Under the condition of solar radiation,the initial brightness can exceed500 mcd/m~2 while the duration time was increased from 400 s to about 6000 s by co-doping Nd³⁺.By means of TL analysis,it indicates that co-doping of Nd³⁺can greatly increase the concentration of shallow traps suitable for Pers L,the trap depth is about0.7 e V.Finally,a feasible Pers L mechanism was discussed.