Characterization of Y2O2S： Eu^3＋, Mg^2＋, Ti^4＋ Long-Lasting Phosphor Synthesized by Flux Method

Long-lasting phosphor Y₂O₂S: Eu³⁺, Mg²⁺, Ti⁴⁺ was synthesized by a flux method and their luminescence properties were investigated. The result indicates that the unit cell parameter c is linearly increased with the increase of Eu₂O₃ content in Y₂O₂S: Eu_x³⁺ (0.01 ≤ x ≤ 0.10). On the other hand, the change of unit cell parameter a is not linear dependence. In the Y₂O₂S: Eu³⁺ crystal structure, Eu³⁺ ions only replaced Y³⁺ ions' places in which it posited center position of c axis. With the increase of Eu₂O₃ content, the position of the strongest emission peak changed from 540 nm (⁵D₁→⁷F₂ transition) to 626 nm (⁵D₀→⁷F₂ transition), and the maximum intensity was obtained when x = 0.09 in Y₂O₂S: Eu_x³⁺ (0.01 ≤ x ≤ 0.10). This is due to the environment of trivalent europium in the crystal structure of Y₂O₂S. Doping with Mg²⁺ or Ti⁴⁺ ions alone cannot get the good long-lasting afterglow effect, whereas co-doping with Mg²⁺ and Ti⁴⁺ ions and excited with 365 nm ultraviolet light, a strong thermoluminesence peak appeared, red and orange long-lasting phosphorescence (LLP) was also observed and the phosphorescence lasted nearly 3 h in the light perception of the dark-adapted human eye (0.32 mcd · m⁻²). Thus the LLP mechanism was analyzed.     

A white long-lasting phosphor Y2O2S:Tb3+, Sm3+: an improvement of Y2O2S:Tb3+

As an improvement of reported Y202S:Tb3 , a white-light long-lasting phosphor: Y2O2S:Tb3 , Sm3 was prepared by the solid-state reaction. The photo-luminescence spectra showed that the position and shape of Th3 and Sm3 emissions under UV excitation were similar in this host, which ensured a stable white emission color (daylight standard of IEC) under different excitations. The decay curves of co-doped samples indicated that the decay times of emissions of the two ions were close. The thermo-luminescence measurement suggested that the traps created by the doped Sm3 ions were helpful to postpone the white afterglow of co-doped samples. Therefore, thefunction of co-doped Sm3 ions was confirmned as improving the white emission colors of samples and acting as new trap centers.     

Luminescence Characterization of Mg Doped Y2O2S:Ti Long Afterglow Phosphor

Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors with long afterglow were synthesized by solid state reaction route. The photoluminescence spectra, decay curves, thermoluminescent spectra and chromaticity coordinate curves were investigated. The results show that the luminescence intensity of Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors decrease gradually with increasing Mg2 ion content, and the shape of luminescence spectra and chromaticity coordinate change as well. Furthermore, two thermoluminescent peaks in single Ti-doped Y2O2S sample are found at 91.8 and 221.5 ℃, respectively. Nevertheless, significant different spectra were found for the Mg, Ti co-doped Y2O2S samples that three thermoluminescence peaks appear at 52.3, 141.7 and 226.8 ℃, respectively. These results indicate that the co-doped Mg ion changes the inherent trap depth of single Ti-doped Y2O2S:Ti phosphor, and induces simultaneously a new trap level in the Y1.94-xMgxO2S:0.06Ti phosphor. Based on the analysis of thermoluminescent spectra, photoluminescent spectra, decay curve and crystal structure defect, it was proposed that the varied structure defect and introduced new trap level by the doped Mg2 ions should be responsible for reducing luminescence intensity and varying color in the Y1.94-xMgxO2S:0.06Ti phosphor.     

Preparation of Stable CaS∶Eu~(2+), Tm~(3+) Phosphor

Alkalineearthsulfides (AES)havebeenfoundtobeexcellentandversatilephosphor ,andrareearthsasactivatorshavebeenintensivelyinvestigated[1～ 7] .Theyholdpromiseforapplicationsinphoto ,electro ,cathoderay ,fieldemissiondisplaysandluminescencepaints[8,9] .However ,alkalineearthsulfidesasaphos phorhosthavebeenfoundtobelimitedinapplica tion ,duemainlytoitssensitivetomoistureandotheratmosphericcomponents .Theirchemicalstabilityagainstatmosphericcarbondioxideandmoisturecouldbeenhancedthroughthegoodcryst…     

A New Yellow Long Lasting Phosphor Y2O2S∶Ti

A new kind of doped rare earth free phosphor Y2O2S∶xTi(0＜x≤0.10) with doped Ti as activative center was synthesized by solid state reaction and sintered at 1200 ℃ for 2.5 h under reducing atmosphere. XRD patterns, photoluminescence spectra, time-resolved phosphorescence spectra and decay curves of the phosphor were investigated. XRD results reveal that a single Y2O2S phase exists with Ti content up to 6%(mol fraction). Yellow long lasting phosphorescence for present materials was observed in the dark with naked eye after the removal of the excitation light. From the time-resolved phosphorescence spectra the broad emission band centered at 565 nm was confirmed to be responsible for the long lasting phosphorescence which could maintain above 1 h. The possible mechanism responsible for the long lasting phosphorescence of the Y2O2S∶Ti phosphor was proposed.     

Adjustable Luminescence of SrAl2O4：Eu^2＋ , Dy^3＋ Assembled in Zeolite

Capsulating guest into the nanometer yoids of zeolites is a effective way to form novel host-guest material. In our work, stoichiometric SrAl2O4: Eu^2 , Dy^3 sol guest was prepared by sol-gel method and assembled into the nanometer channels of zeolite ZSM-5 host through mechanical mixing, hydrothermal reaction and microwave heating reaction, respectively. After being reduced and diffused in a microwave muffle, the fluorescence spectra of the host-guest materials exhibit remarkable blue shifts in comparison of that of SrAl2O4 : Eu^2 , Dy^3 . Some interesting phenomena in the assembled hostguest materials are that the after-glow emission spectra exist two bands at about 400 nm and 517 nm and the relative strengths of these two bands can be adjusted by changing the assembly methods and the assembly concentration. These are attributed to the fact that the phosphor was capsulated into the voids of zeolite ZSM-5 and generated the quantum size effect and the host-guest effect.     

SrAl_2O_4∶Eu~(2+),Nd~(3+) and Dy~(3+) Long Afterglow Phosphor

Longafterglowphosphorabsorbingenergyfromsolar,lampandotherlightsourcesforashorttimestorestheenergyandexhibitsbrightandlong lastingphosphorescencewhichsuitsthevisualperceptionofthehumaneyewithminimumbrightness 0 32mcd·m- 2 andlastingtimemorethan 8h) .TheSrAl2 O4 ∶Eu2 +,Dy3+phosphorhasbeenknowntobeagreenlongafterglowphosphorwithanemissionpeakat 5 2 0nm[1～ 7] .ThepropertiesofthephosphorwerefurtherexaminedbythegroupofTangMingdaoandMatsuzawaTindetailin 1995and 1996respectively[1,2 ] .Inorde…     

SrAl2O4 :Eu2+, Dy3+ Long Afterglow Phosphors Prepared by Chemical Coprecipitation Method

SrAl2 O4: Eu2 , Dy3 long afterglow phosphors were prepared by chemical coprecipitation method. Ammonium carbonate and ammonium hydrogen carbonate were used as the precipitants. The preparation of the SrAl2 O4: Eu2 ,Dy3 precursor was completed at room temperature by controlling the concentration of the metal-salt solution, pH value of the system, etc. The phosphors were prepared by sintering the precursor at 1000 ～ 1200 ℃ in a weak reducing atmosphere for 2 h. The XRD, SEM, excitation spectra, emission spectra and afterglow decay of the samples were tested and the optimal synthesis conditions of the SrAl2O4: Eu2 , Dy3 long afterglow phosphors prepared by precipitation method were determined. The phosphor which had good luminescent properties is prepared and its persistent time can reach more than 1600 min. In the coprecipitation process, a small amount of glucose operates to refe the luminescent powders. The particle size of the phosphor can be less than 1 μm. The sintering temperature of the sample prepared by the coprecipitation method is much lower than that of the one prepared by the high temperature solid state method.Compared with the high temperature solid state method, a clear blue shift occurs in the excitation and emission spectra of the samples.     

Preparation and Luminescence of SrAi2O4:Eu2+, Dy3+ Nano-Particle

SrAl2O4: Eu2 , Dy3 nano-particle luminescence material was prepared by sol-gel method. Influences of synthesis conditions on the particle size and luminescence properties of SrAl2O4: Eu2 , Dy3 were studied. The synthesis process and the properties of the samples were analyzed by DTA, TGA, XRD, SEM. The result suggested that the formation of SrAl2O4: Eu2 , Dy3 sol is a slow heat release process beginning at 500 ℃ and peaking at 759 ℃.SrAl2O4: Eu2 ,Dy3 crystalline was formed at 1100 ℃. The luminescence properties of the SrAl2O4: Eu2 , Dy3 nanoparticle were compared with the conventional SrAl2O4: Eu2 , Dy3 particles. The average particle size of the product is about 30 nm. The excitation spectrum of the sample shows a broad band with peaks at 240, 330, 378 and 425 nm. The emission spectrum is a broadband spectrum with a peak at 523 nm.     

Influence of Flux on Structure and Luminescence of LaMgB5O10:Ce3+,Mn2+

The influences of the flux KCl or KF on the XRD patterns,cell parameters,crystal morphology,and spectral properties of the phosphor 12.8% KCl and 5.3%,10.5% KF are added individually into the phosphor (La0.85Ce0.15)(Mg0.9Mn0.1) B5O10,some peaks of the XRD patterns are intensified and cell volumes are decreased. A small amount of Cu mono-crystal typed phase appears as more than 5% KCl is added. There are six hexagonal crystal-faces and eight triangular crystal-faces attributed to the {100} and {111} respectively. When 15% KCl is added into the phosphor,multi-faced regular crystals are formed and the crystal self-regulation appears. The emission intensity of 5d→4f(2F5/2,2F7/2) of Ce3 and 4G→6S of Mn2 increases up 3.41 and 2.36 times respectively.     

Red Emitting Phosphor (Y,Gd)BO3:Eu3+ for PDP Prepared by Complex Method

Red phosphor (Y, Gd)BO3:Eu3+ with grain shape, small size, non-agglomerate, high crystallinity and good photoluminescence (PL) intensity was prepared by a complex method that the precursor of the phosphor was prepared by co-precipitation method and the phosphor was prepared by combustion method. The SEM photos and the photoluminescence spectrum excited under VUV show that the morphology and luminescent properties of this phosphor are satisfied when an appropriate amount of urea was adopted as the combustion agent in the preparation procedure.     

Eu~(2+) Luminescence in BaZnAl_(10)O_(17)∶ Eu Phosphor

Ａｎｉｍｐｏｒｔａｎｔｃｌａｓｓｏｆｆｌｕｏｒｅｓｃｅｎｔｌａｍｐａｎｄｐｌａｓｍａｄｉｓｐｌａｙｐｈｏｓｐｈｏｒｓｉｓｂａｓｅｄｏｎｃｏｍ ｐｏｕｎｄｓｏｆｔｈｅａｌｋａｌｉｅａｒｔｈ ｒａｒｅｅａｒｔｈａｌｕｍｉｎａｔｅｓｙｓｔｅｍｓｂｅｃａｕｓｅｏｆｔｈｅｉｒｈｉｇｈｌｕｍｉｎｅｓｃｅｎｔｅｆｆｉ ｃｉｅｎｃｙａｎｄｓｔａｂｉｌｉｔｙｕｎｄｅｒｕｌｔｒａｖｉｏｌｅｔａｎｄｖａｃｕ ｕｍｕｌｔｒａｖｉｏｌｅｔｌｉｇｈｔｅｘｃｉｔａｔｉｏｎ[1] .Ｅｓｐｅｃｉａｌｌｙ ,ａｌｋａｌｉｎｅｅａｒｔｈｈｅ…     

Synthesis of Long Afterglow Phosphor CaAl2Si2O8:Eu2+, Dy3+ via Sol-Gel Technique and Its Optical Properties

The long afterglow phosphor CaAl2Si2O8:Eu2 , Dy3 was prepared by a sol-gel method. The sol-gel process and the structure of the phosphor were investigated by means of X-ray diffraction analysis (XRD). It is found that the single anorthite phase formed at about 1000 ℃, which is 300 ℃ lower than that required for the conventional solid state reaction. The obtained phosphor powders are easier to grind than those of solid state method and the partical size of phosphor has a relative narrow distribution of 200 to 500 nm. The photoluminescence and afterglow properties of the phosphor were also characterized. An obvious blue shift occurs in the excitation and emission spectra of phosphors obtained by sol-gel and solid state reaction methods. The change of the fluorescence spectra can be attributed to the sharp decrease of the crystalline grain size of the phosphor resulted from the sol-gel technique.     

Effect of Organic Solvent and Resin on Luminescent Capability of SrAl2O4:Eu2+, Dy3+ Phosphor

Organic substance such as solvent and resin's effect on luminescent capability of SrAl2O4:Eu2 , Dy3 phosphor was studied. Some organic solvents and resins were selected for experimentation. The results indicate that those organic solvents will not have negative effect on the applied capability of SrAl2O4:Eu2 , Dy3 phosphor. Adopting the organic resins and covering method, the afterglow luminance of SrAl2O4:Eu2 , Dy3 phosphor was increased by 85.01% and 82.51%.     

Luminescent Properties of Y_2O_3∶Eu Nanocrystalls Synthesized by EDTA Complexing Sol-Gel Process

Ｎａｎｏｐａｒｔｉｃｌｅｓａｎｄｎａｎｏｃｌｕｓｔｅｒｍａｔｅｒｉａｌｓａｒｅａｎｅｗｃｌａｓｓｏｆａｄｖａｎｃｅｄｍａｔｅｒｉａｌｓｅｘｈｉｂｉｔ ｉｎｇｕｎｉｑｕｅｃｈｅｍｉｃａｌａｎｄｐｈｙｓｉｃａｌｐｒｏｐｅｒｔｉｅｓｃｏｍｐａｒｅｄｔｏｔｈｏｓｅｏｆｔｈｅｉｒｂｕｌｋｍａｔｅｒｉａｌｓ[1 ] .Ｙ2 Ｏ3 :Ｅｕｉｓａｎｅｆｆｉｃｉｅｎｔｒｅｄ ｅｍｉｓｓｉｏｎｐｈｏｓｐｈｏｒｗｈｉｃｈｈａｓｂｅｅｎｕｓｅｄｉｎｆｌｕｏｒｅｓｃｅｎｔｌｉｇｈｔｓ (ＦＬ)ａｎｄｃａｔｈｏｄｅｒａｙｔｕｂｅ (ＣＲＴｓ…     

SrAl2O4:Eu, Dy Nanometer Phosphors Synthesized by Combustion Method

SrAl2 O4: Eu, Dy nanometer phosphors were synthesized by combustion method at 500 ～ 900℃, followed by heating the combustion sample at 1150℃ at a weak reductive atmosphere and nanometer phosphor with much better luminescent properties was obtained. The influences of the initiating combustion temperature, H3BO3 quantity, the mass ratio of urea and nitrate on the luminescent intensity of nanometer phosphors were studied. The optimum synthetic conditions were determined. The analysis results by transmission electron microscopy (TEM) indicate that the particle size of the synthetic product is less than 75 nm. The luminescent materials do not need to be ground. Their coating can be refined. It supplies a new approach to the rapid preparation of the luminescent materials at low temperature. The excitation and emission spectra indicate that the main peaks in the excitation and emission spectrum of nanometer phosphor synthesized by combustion method shifted to the short wavelength compared with the phosphor obtained by the solidstate reaction synthesis method. The reason of blue shift was explained. The afterglow decay results indicate that the decay speed of the afterglow for nanometer phosphor is faster than that obtained by the solid-state reaction method.     

Synthesis and Luminescence Properties of Red Phosphors:Mn2+ Doped MgSiO3 and Mg2SiO4 Prepared by Sol-Gel Method

Sol-gel method was utilized to synthesize two different series of red silicate phosphors:MgSiO3 and Mg2SiO4 powder samples doped with Mn2 , conducted the investigation of red long-lasting phosphor: MgSiO3:Eu2 , Dy3 , Mn2 . TGA curves of the gel precursor for two series depicted that the loss of residual organic groups and NO3 groups occurs below 450 ℃. According to the XRD patterns, the major diffraction peaks of the MgSiO3 and Mg2SiO4 series are consistent with a proto-enstatite structure (JCPDS No.11-0273) and a forsterite structure (JCPDS No.85-1364) respectively. With the excitation at 415 nm, the red emission band of Mn2 ions is peaked at 661 nm for MgSiO3:1%(atom fraction) Mn2 or 644 nm for Mg2SiO4:1%(atom fraction) Mn2 . Compared with Mg2SiO4:Mn2 samples, MgSiO3:Mn2 samples exhibit higher luminescence intensity and higher quenching concentration. In addition, the two series co-doped with Eu2 , Dy3 , Mn2 were also prepared. Photo-luminescence and afterglow properties of the two co-doped series were analyzed, which show that MgSiO3:Eu2 , Dy3 , Mn2 is more suitable for a red long-lasting phosphor.     

Preparation of Orange-Red Long Afterglow Phosphors Y2O2S:Sm3+, Mg2+, Ti4+

The orange-red long afterglow phosphors Y₂O₂S:Sm³⁺, Mg²⁺, Ti⁴⁺ was prepared by high temperature solid-state method. By XRD analysis, the crystal phase of the sample was Y₂O₂S, belonging to hexagonal system, and no new crystal phase arose when doping Sm³⁺, Mg²⁺, Ti⁴⁺. The characteristic peaks of excitation spectrum were located at 373, 388, 417, 430, 475 and 491 nm, and the characteristic peaks of emission spectrum were located at 571, 609 and 657 nm. The content of Sm³⁺ and doped ions Mg²⁺, Ti⁴⁺ affected the luminescent properties obviously, and Sm³⁺ affected the luminescent brightness mainly. Mg²⁺ and Ti⁴⁺ could deepen properly trap energy of Y₂O₂S crystal and strengthen its afterglow properties, the brightness and afterglow properties of sample were better when the mole ratio of Sm/Y, Mg/Y and Ti/Y is 1.4%, 1.25% and 0.9%, respectively.     

Study on Luminescence Properties and Crystal-Lattice Environment of Eu~(2 ) in Sr_(4-x)Mg_x Si_3O_8Cl_4∶Eu~(2 ) Phosphor

ChlorosilicatecrystalmaterialM4 Si3O8Cl4 (M =Ba ,Sr ,Ca)isasuitablehostlatticeforluminescencematerials .Adivalenteuropiumactivatedstrontiumchlorosilicatephosphorisakindofgoodblue greenemissionphotoluminescencematerialunderUVexcita tion .Itsluminescencepropertiesandcrystalstructurehavebeenintensivelystudied[1～4 ] .Inthechlorosili catehost ,theluminescenceofEu2 consistsofa4f6 5d1- 4f7(8S7/2 )broad bandemission ,whichbe longstoelectric dipoleallowedtransitionandhasthepropertiesoflargeabso…     

新型红色长余辉发光材料Y2O3∶Eu3+,Ca2+,Ti4+的燃烧合成和性能表征

采用燃烧法合成了新型红色长余辉发光材料Y2O3∶Eu3+,Ca2+,Ti4+.用X射线衍射仪表征了其结构;用荧光光谱仪测试了激发、发射光谱;以紫外-可见分光光度计测定分析了样品的反射光谱特征.XRD分析证实为立方相的Y2O3.激发光谱为一紫外区内的宽带谱,中心位于253nm,属于Eu3+-O2-的电荷迁移跃迁;发射光谱峰值位于613 nm,对应于Eu3+的5D0→7F2跃迁发射.由于掺杂离子不等价的取代Y3+,形成了电子陷阱和空穴陷阱,两者的复合作用延缓了余辉的衰减.紫外-可见反射光谱得到的结论与荧光激发光谱的结果一致.该样品在紫外线激发下余辉时间长达90分钟.