Research On The Luminescence Properties Of Rare Earth Doped Li?Y/Gd?₅P₂O₁₃ And Na_0.34Ca_0.66Al_1.66Si_2.34O₈ Phosphor

White light emitting diodes?LEDs?have been used in lighting,LED display,LCD background light,medical imaging,LED grow lights and other fields due to its small size,long lifetime,high energy efficiency,environmentally friendly and saving energy,and has become a hot spot in the field of international lighting research.The main approach to fabricate WLED devices is to combine a blue or UV chip with the phosphor,obviously,the phosphor plays an important role in the LED device.Therefore,one of the works of this paper is to research red phosphors?which can be excited by UV/NUV light?and the high color rendering indexed phosphor.We selected phosphate as the matrix material.Moreover,as one of the photoluminescence material,long afterglow phosphors has been widely studied because of its special optical properties which can absorb light,store energy,and release energy as visible light lasting for several hours at room temperature.Up to now,long afterglow materials have been applied in emergency signs,electronic displays,decorations and other civil fields.More importantly,long afterglow materials have also become one of fundamental materials for biomedical optical techniques and military nightvision monitoring technique.Consequently,another work of this paper is to study the afterglow properties of the rare earth doped Na_0.34Ca_0.66Al_1.66Si_2.34O₈ phosphor.The specific research includes the following three aspects:?1?A new red-emitting phosphor LiY₅P₂O₁₃:Eu³⁺ has been prepared using a conventional high-temperature solid-state method.Under the excitation of 394 and 467 nm,Li Y5P2O13:Eu³⁺ shows a strong red light emission with high color purity.The optimum Eu³⁺ concentration is 10 mol%,and then the PL intensities decrease with increasing Eu³⁺ concentration.The concentration quenching mechanism has been investigated by Dexter's theory,and demonstrated to involve a dipole-quadrupole interaction.The J-O theoretical studying results indicate that Eu³⁺ ions have a high probability of transition in this phosphor,so LiY₅P₂O₁₃ phosphors possess the high quantum efficiency.Photoluminescence and thermal quenching properties of the synthesized LYPO:0.1Eu³⁺ have been compared with Y2O2S:Eu³⁺ and Sr2Si5N8:Eu²⁺,which suggests that the LYPO:0.1Eu³⁺ has a good potential application in white LED.?2?A series of Bi³⁺ and/or Eu³⁺ doped LiGd₅P₂O₁₃?LGPO?were synthesized via a solid state reaction.Under the excitation of 290 nm,LiGd₅P₂O₁₃:Bi³⁺shows a broad bluish-green emission from 380 to 650 nm.Based on the Bi³⁺?Eu³⁺ energy transfers.The single-phase white-light-emitting phosphor LiGd₅P₂O₁₃:Bi³⁺,Eu³⁺ were realized by energy transfer from Bi³⁺ to Eu³⁺ ions,and its optical properties were studied in detail,such as luminescence,the mechanism of energy transfer and tunable color emitting.The sample withoptimal composition of LGPO:0.1Bi³⁺,0.01Eu³⁺ exhibits a white light emission with a high CRI of 82,a low CCT of 4250 K and color coordinates of?0.372,0.328?.?3?The blue persistent phosphor Na_0.34Ca_0.66Al_1.66Si_2.34O₈:Eu²⁺,Dy³⁺ was synthesized successfully via a high temperature solid-state reaction.When the Eu²⁺ ions were solely doped in the host,a broad blue light emission peaking at425 nm was observed under the NUV light excitation.After excitation was ceased,NCASO:Eu²⁺ shows a weak afterglow.The co-doped Dy³⁺ ions into the can effectively enhance the luminescence intensity and prolong the persistence time.In order to analysis the role of Dy³⁺ ions,the PL/PLE spectra,afterglow decay curves and TL curves were measured and studied in detail.