Preparation Of Silicate Based Long Persistent Luminescence Materials Using Coordination Polymers As Precursors

Long persistent luminescence materials are a type of green materials that can store light energy and emits constant visible light in the dark after being excited by visible light or ultraviolet light.The possess reusable,energy efficient and environmentally-friendly advantages,and have broad application prospects in various fields.Among them,silicate long persistent luminescence materials have been widely applied in luminous dials,anti-counterfeit marking,sensing detection,medical diagnosis and other fields due to the advantages of low cost,high physical and chemical stability,multicolor luminescence and stable luminous performance under humid conditions.Generally,silicate long persistent luminescence materials consist of two parts:the matrix and doping ions as the luminescent center.The matrix itself exists presenting afterglow luminescence was rarely reported.Also,the synthesis method is the traditional high temperature solid phase method,which usually requires high energy consumption and the particle size of the synthesized product tends to be big.The development of new synthesis methods is concentratedly investigated.Herein,we have prepared silicate composites with afterglow properties without other rare earth ion doping by high-temperature solid-phase method using coordination polymers as precursors,and investigated the effect of rare earth ion doping on their luminescence properties using the prepared silicate composites as substrates.The specific research content is listed as follows.（1）Preparation of transition metal coordination polymer room temperature phosphorescent materials and study on their luminescence propertiesZinc-based coordination polymer room-temperature phosphorescent materials（Zn CP）and cadmium-based coordination polymer room-temperature phosphorescent materials（Cd CP）were synthesized by the solvothermal method using 2,3-pyridinedicarboxylic acid as the organic ligand and reacting with zinc acetate dihydrate and cadmium acetate dihydrate,respectively.A series of characterization results showed that Zn CP is small particle at the nanoscale and Cd CP is small particle at the micron scale.The green afterglow of more than 2 s was observed with the naked eye at room temperature after being excited with UV light at 365 nm.（2）Preparation of silicate composites based on coordination polymers as precursors and study on their luminescence propertiesBased on the above successful synthesis,the silicate composites Cd Zn_1.5Si_1.75O₆were synthesized by high-temperature solid-phase method using Zn CP and Cd CP as precursors,and then mixed and ground with Si O₂ The optimum conditions for the synthesis of the silicate composite micron-sized materials were investigated as 1:1,75mg of Si O₂ input,1000℃and 4 h by adjusting the Zn CP:Cd CP ratio,Si O₂ input,calcination temperature and calcination time.Under the UV excitation at 254 nm,the materials emitted bright orange-yellow luminescence,and the afterglow time was as long as 160 min after stopping excitation.The study showed that compared with the conventional high temperature solid phase method,the prepared ion-free doped long persistent luminescence materials using a ligand polymer as precursor possessed the advantages of low reaction temperature,small particle size and long afterglow time.This method provides a new strategy for the design and synthesis of ion-free doped long persistent luminescence materials.（3）Preparation of rare earth ion-doped silicate composites and study on their luminescence propertiesTo further optimize the product properties,the prepared silicate composites were doped with rare-earth ions.The effects of doping different Sm³⁺and Tb³⁺ions on the luminescence properties of the Cd Zn_1.5Si_1.75O₆ matrix were investigated.The structure and luminescence properties of the materials were investigated under the optimum doping conditions(1.5%for both Sm³⁺,Tb³⁺).The results showed that the doping of rare earth ions improved the luminescence performance of the materials and significantly extended the afterglow time by nearly 2.8 and 3.3 times compared to Cd Zn_1.5Si_1.75O₆,respectively.