Study On The Luminescence Properties Of Alkaline Earth Metals Doped With Ions

Long afterglow luminescent materials can absorb energy under the excitation of natural light or ultraviolet light then store them.After the excitation,the energy stored will be released in the form of visible light and continues for some time.The research of long afterglow luminescent materials has attracted more and more attention in the current society with increasingly tense resources.At present,long afterglow luminescent materials can used in many important fields,such as arts and crafts,emergency lighting,light lighting,storage medium,high energy ray detection,biological imaging in vivo,etc.It is generally believed that the generation of long afterglow is that the electrons or holes in the valence band or guide band can be captured by the electron trap and hole trap under the excitation.After removal of excitation,the electrons and holes captured in these traps can be released under appropriate thermal disturbances and produce a long afterglow phenomenon.Therefore,choosing an appropriate substrate and luminescent center can bring a better performance of long afterglow luminescence.Based on this principle,researchers in this field have synthesized various kinds of long afterglow phosphors with different activators on different lattice bodies.In recent decades,rare earth ions doped long afterglow luminescent materials have developed rapidly and Mn2+ions doped zinc or magnesium germanate salts have attracted people's interest due to their potential applications in the field emission display.At present,Mn²⁺doped germanate has been reported in Na₂ZnGeO₄:Mn²⁺,Li₂ZnGeO₄:Mn²⁺,CaZnGe₂O₆:Mn²⁺,Zn₂GeO₄:Mn²⁺and Mn²⁺doped MgO-GeO2.However,the green light afterglow of Mn²⁺doped germanate is relatively short.that due to the poor caused by its poor defects.The appropriate trap energy level and trap density play a key role in long afterglow phosphor material.In order to improve the afterglow strength and duration,we need to add auxiliary activator to introduce other defects.In this paper,we chose to add Cr3+ions as auxiliary activators.Therefore,this paper introduces the preparation of Li₂MgGeO₄:Mn²⁺and Li₂MgGeO₄:Mn²⁺,Cr³⁺phosphors.The main work and conclusions are as follows:First,in order to explore the optimization of Li₂Mg_1-x%GeO₄:x%Mn²⁺long afterglow materials with high temperature solid-phase preparation process,Li₂Mg_1-x%GeO₄:x%Mn²⁺material samples were prepared at different sintering temperatures,different doping concentration of Mn²⁺ions and excessive addition of GeO₂.The samples of Li₂Mg_1-x%GeO₄:x%Mn²⁺were characterized by XRD,excitation spectrum,emission spectrum and afterglow attenuation curve,and the influence of the preparation process on the crystal and optical properties of the materials was studied.Secondly,the appropriate trap energy level and trap density play a crucial role in the long afterglow phosphor materials.In order to improve the afterglow strength and duration,the auxiliary activator is needed to introduce other defects.Cr³⁺ions were selected as auxiliary activators.The samples of Li₂MgGeO₄:Mn²⁺,Cr³⁺long afterglow phosphor were prepared at different sintering temperatures and the doping concentration of Cr³⁺ions respectively.The samples of Li₂MgGeO₄:Mn²⁺,Cr³⁺were characterized by XRD,excitation spectra,emission spectra and afterglow attenuation curves.The effects of the preparation process and the addition of auxiliary activator Cr3+ ions on the crystallization and optical properties of the materials were investigated.Finally,using the CASTEP calculation module of the Material Studio software by first principle,the Mn²⁺single doping of Li₂MgGeO₄ and the co doping of Mn²⁺and Cr³⁺are calculated,and the mechanism of the afterglow emission and the possible causes for the change of the afterglow properties of the two chapters before the emergence of the two chapters are investigated.The afterglow mechanism model of Li₂MgGeO₄ is put forward.