Studies On Luminescence Properties Of Apatite Phosphors Based On Energy Transfer And Structural Regulation

The luminescence properties of the phosphor depend on both the host lattice and the doping ions.Studying how to effectively regulate the luminescence properties is of great significance for the development of new luminescent materials.In this paper,focusing on the spectral regulation,the phenomenon and mechanism of spectral regulation introduced by energy transfer and host composition tuning were studied through the construction of different ion co-doping systems in apatite structure hosts,which could provide some references for improving the performance of white light-emitting diodes.The main results and achievements are as follows:The crystal structure,morphology,photoluminescence properties as well as energy transfer mechanism of the Sr₄La(PO₄)₃O:Ce³⁺,Mn²⁺phosphor were systematically investigated.The results of spectral analysis reveal that Ce³⁺occupies three non-equivalent sites in the Sr₄La(PO₄)₃O lattice.Upon ultraviolet light excitation,the Ce³⁺ion-activated phosphor has a relatively broad emission band,which exhibits a significant shift when altering the excitation wavelength.The investigations on the Ce³⁺and Mn²⁺co-doped Sr₄La(PO₄)₃O phosphor show that the energy transfer mechanism is dipole-dipole interaction,which can regulate the emission color of the phosphor.With the increase of the concentration ratio of Mn²⁺to Ce³⁺,the emission color of the phosphor can be adjusted from blue to white.Based on Sr₄La(PO₄)₃O,the solid-solution Sr_4-xCa_xLa(PO₄)₃O was designed and prepared.The luminescence properties of Sr_4-xCa_xLa(PO₄)₃O:Eu²⁺phosphors and the mechanism of fluorescence regulation introduced by host composition tuning were studied.The host composition tuning can induce the change of centroid displacement and crystal field splitting of the 5d level of Eu²⁺,as well as the evolution of Stokes shift,and then the luminescence properties of the phosphor can be regulated.Furthermore,the Eu²⁺,Tb³⁺and Eu²⁺,Mn²⁺co-doped(Sr Ca)₂La(PO₄)₃O systems were investigated.The effect of energy transfer on the photoluminescence spectra and the mechanism of energy transfer were explored.The luminescence properties of Eu²⁺-Tb³⁺-Mn²⁺three-ion-doped systems were studied to explore the way for achieving white light emitting.Finally,the w LED was packaged using the synthesized sample,and the results indicate the application potential of the phosphor.The crystal structure,photoluminescence properties and energy transfer mechanism of the Ca₄La₆(Si O₄)₄(PO₄)₂O₂:Tb³⁺,Mn²⁺phosphors were studied.The Ca₄La₆(Si O₄)₄(PO₄)₂O₂:Tb³⁺phosphor has a relatively high internal quantum efficiency and excellent thermal stability,so that the application potential of the phosphor can be expected.In the Tb³⁺and Mn²⁺co-doped Ca₄La₆(Si O₄)₄(PO₄)₂O₂ system,the orange-red emission band of Mn²⁺can be induced by the efficient energy transfer from Tb³⁺,thus the regulation of the photoluminescence spectrum can be realized.As the concentration ratio of Mn²⁺to Tb³⁺increases,the emission color of the phosphors gradually change from green to orange-red under near-ultraviolet excitation.The highly efficient red luminescence materials Ca₄La₆(Si O₄)₄(PO₄)₂O₂:Eu³⁺were synthesized and the crystal structure,photoluminescence properties as well as the optical sensing properties were investigated.The site occupation information of Eu³⁺in Ca₄La₆(Si O₄)₄(PO₄)₂O₂ and the characteristics of crystal field around Eu³⁺were obtained through the spectral analysis combined with the Judd-Ofelt theory.The application prospects of the phosphor in the field of high color rendering solid state lighting was proved by packaging the LED lighting device.The intrinsic thermal quenching mechanism of Ca₄La₆(Si O₄)₄(PO₄)₂O₂:Eu³⁺was explored,and the potential value of the sample for optical temperature measurement was revealed.Some theoretical and experimental references for exploring the spectral regulation mechanism can be provided through the research results,and it is expected to be helpful for the enrichment of luminescence mechanism and the development of luminescent materials.