Rare Earth Doped Silica/Aluminates Ca₂Al₂SiO₇ And CaYAl₃O₇ Luminescence Properties And Applications Of Fluorescent Materials

The thermal stability of phosphor is the key to the high luminous efficiency of luminescent devices.Compared with chemical stability,the thermal stability problem is more important.The emission intensity of the phosphor decreases with the increase of the external temperature.It has become a bottleneck restricting the expansion of W-LED to high-power applications.In this paper,a series Tb³⁺ions doped phosphors of Ca_2-xY_xAl₂Si_1-xAl_xO₇(x=0-1)fluorescent material were synthesized by high-temperature solid-phase method.Through the characterization of the structure and luminous properties of the series of samples,the changes in the local structure were explored.Polychrome phosphor materials are synthesized after introduced the different rare earth ions(Sm³⁺,Tb³⁺,Eu³⁺,Dy³⁺,Pr³⁺).In this process,we explored the thermal stability of the developed luminescence materials and their potential applications in W-LEDs.In addition,we also explored the luminescence behavior of the dual-mode output of Eu²⁺and Eu³⁺ions in different valence states in silicon/aluminate,and their application in multiple anti-counterfeiting.The research results are as follows:1.By using the melilite structure material Ca₂Al₂Si O₇(CAS)with Al³⁺-Y³⁺substitute Si⁴⁺-Ca²⁺to manipulate the local structure,and then formed Ca YAl₃O₇(CYA)matrix.The result shows that the shortening of the bond length increases the pressure of the local structure to suppress the non-radiative transition of the rare earth ions,which effectively improves the structural stability of CYA,and finally achieves high thermal stability of CYA:0.01Ln³⁺(Eu³⁺,Sm³⁺,Dy³⁺,and Pr³⁺).In addition,a possible thermal quenching mechanism is proposed to explain the electronic transition pathways in phosphor materials based on the transition energy levels of CYA:0.01Pr³⁺samples.2.According to the above research results,the rare-earth ions Eu³⁺,Tb³⁺co-doped in CYA matrix to find the optimal luminous concentration,and explore the photoluminescence properties and energy transfer process,especially the thermal stability of the samples.Then,by characterized the luminescence properties of the sample and measured the electroluminescence spectrum of fabricate W-LEDs,its potential applications in the field of lighting display are analyzed.3.Owning to the presence of multiple cationic ion lattices in the material,under reducing atmosphere,Eu²⁺and Eu³⁺coexisting phosphor materials with a single blue long persistent luminescence(Eu²⁺)were synthesized,and only the blue persistent luminescence of Eu²⁺was observed.Therefore,under different irradiation conditions(UV irradiation and removal of irradiation),CYA:Eu²⁺/Eu³⁺will have different luminous colors.In addition,due to the coupling of Eu²⁺and Eu³⁺ions,the photoluminescence of CYA:Eu²⁺/Eu³⁺shows different colors under different excitation wavelengths.At the same time,by doping Nd³⁺ions,the blue and red emission of the phosphor can be effectively manipulated,and the long persistent luminescence performance of CYA:Eu²⁺/Eu³⁺can be significantly improved,which makes the phosphor show dynamic luminescence characteristics with the change of time and temperature.