Preparation And Properties Of Sr₃Al₂O₆:Eu Based Mechanoluminescent Flexible Composites

Mechanoluminescence material has great application potential in the field of illumination,display,imaging,anti-counterfeiting,sensing,etc.In recent years,more and more researchers have drawn attention.However,at present,there is a relative lack of research system and application development of the mechanoluminescence materials.In this dissertation,a new type of color-adjustable flexible mechanoluminescence composite material was developed through the structural design of materials,the selection of reaction conditions,the luminescence and thermoluminescence performance characterization and analysis,and its application in the field of engineering was carried out.The main contents are as follows:1.Sr₃Al₂O₆:Eu³⁺red mechanoluminescence powder was prepared by high temperature solid phase method.The crystal structure and surface morphology of the red phosphor powder were analyzed by XRD and SEM.By combining with the flexible matrix PDMS,Sr₃Al₂O₆:Eu³⁺/PDMS composite material was further obtained.The results show that when the concentration of Eu3+ion reaches8%,the photoluminescence and the mechanoluminescence of the composite flexible body reach the highest intensity.Through thermoluminescence spectrum,the trap depth and carrier density of the Sr₃Al₂O₆:Eu³⁺mechanoluminescence material before and after being stressed were analyzed,and the mechanism of the mechanoluminescence was discussed.2.Based on the synthesis of Sr₃Al₂O₆:Eu³⁺,two kinds of Sr₃Al₂O₆:Eu³⁺,Eu²⁺powders with different reduction degrees were prepared by using N₂ or H₂/N₂ reaction atmosphere.XRD and XPS were used to analyze the phase,structure and chemical composition of Eu³⁺in Sr₃Al₂O₆ structure,and Sr₃Al₂O₆:Eu³⁺,Eu²⁺/PDMS composite flexible structures were further prepared.Due to the reduction of part of Eu³⁺,photoluminescence and mechanoluminescence of Sr₃Al₂O₆:Eu³⁺,Eu²⁺/PDMS achieve color adjustment from red to green and from red to yellow-white,respectively.The depth of traps and carrier density of the Sr₃Al₂O₆:Eu³⁺,Eu²⁺powders before and after being stressed was calculated by means of thermoluminescence spectrum,and the corresponding phenomenon of mechanoluminescence was explained.3.In this paper,based on the study of Sr₃Al₂O₆:Eu³⁺/PDMS red mechanoluminescence elastomers,a flexible device with dual-mode anti-counterfeiting is developed.It can make the encrypted information clearly displayed under ultraviolet irradiation or under stretching conditions.In addition,based on the mechanoluminescence and photoluminescence properties of Sr₃Al₂O₆:Eu³⁺and Sr₃Al₂O₆:Eu³⁺,Eu²⁺,through a two-layer design,a flexible sensor with both tensile strain and tensile state sensing is developed.