Eu~(2+)激活的钡镁多铝酸盐磷光体的合成

本文试验了合成BaMg_2Al_(16)O_(27):Eu~(2+)的一些主要因素如灼烧温度,一些化学组分改变的影响。试验表明,提高灼烧温度有利于产物发光,但灼烧温度高于1340℃发光亮度不再增加,合适的Eu~(2+)掺入浓度在0·12～0·18克原子范围。Mg~(2+)量和配方中F量的不同对发光亮度、萤光光谱、色纯度和粒度均有影响,通过试验得到了较适宜的BaMg_2Al_(16)O_(27):Eu~(2+)磷光体的制备条件。     

新型蓝色长余辉荧光粉SrAl_2O_(4-y)N_y∶Eu~(2+),Dy~(3+)发光性能研究

采用高温固相反应合成了SrAl_2O_(4-y)N_y∶Eu~(2+),Dy~(3+)系列长余辉荧光粉,并研究了SrAl_2O_(3.75)N_(0.25)∶Eu~(2+),Dy~(3+)体系的晶体结构、光谱特性、余辉衰减曲线及热释发光曲线。X射线衍射分析结果表明,SrAl_2O_(3.75)N_(0.25)∶Eu~(2+)荧光材料属六方晶系,P6322空间群,晶胞参数a=b=5.14,c=8.462,γ=120°。荧光光谱测试结果表明,SrAl_2O_(3.75)N_(0.25)∶Eu~(2+)的激发光谱和发射光谱均为宽带谱,激发光谱位于283 nm~450 nm,发射光谱的峰值位于487 nm,属于Eu~(2+)的4f65d1→4f7跃迁发射。Eu~(2+)的掺杂量并不改变SrAl_2O_(3.75)N_(0.25)∶Eu~(2+)发射光谱的形状和峰值位置,但对相对发光强度有较大影响,Eu~(2+)的摩尔浓度为2%时相对发光强度最高。余辉衰减曲线表明,Sr_(0.97)Al_2O_(3.75)N_(0.25)∶Eu_(0.02),Dy_(0.01)的余辉衰减符合指数衰减规律,由初始的快衰减和之后的慢衰减两个过程组成。通过热释发光曲线对荧光材料中的陷阱能级进行计算,得出Sr_(0.97)Al_2O_(3.75)N_(0.25)∶Eu_(0.02),Dy_(0.01)的能级陷阱为0.42 V,掺Dy~(3+)有利于提高该荧光材料的初始发光亮度和余辉时间。     

Yb~(3+)共掺杂Sr_2MgSi_2O_7∶Eu~(2+),Dy~(3+)长余辉发光材料的制备与性能研究

通过高温固相法制备了Sr_2MgSi_2O_7∶Eu~(2+),Dy~(3+),Yb~(3+)长余辉发光材料。采用XRD、SEM、激发光谱、发射光谱和余辉衰减曲线对Sr_2MgSi_2O_7∶Eu~(2+),Dy~(3+),Yb~(3+)长余辉发光材料的微观结构以及光学性能进行了表征,研究结果表明Sr_2MgSi_2O_7∶Eu~(2+),Dy~(3+),Yb~(3+)长余辉发光材料的晶体结构和显微结构均未发生明显变化。Yb~(3+)的引入使得Sr_2MgSi_2O_7∶Eu~(2+),Dy~(3+)显示出更优良的荧光性能和余辉性能,不同Yb~(3+)掺量对长余辉发光材料的陷阱深度和电子传输速率有显著影响。实验表明,当Yb~(3+)掺杂量为0.03时,Sr_2MgSi_2O_7∶Eu~(2+),Dy~(3+),Yb~(3+)的荧光光谱相对强度最强,且表现出最佳的余辉衰减性能。     

Effects of Doping Trace Sm~(3+) and Gd~(3+) on Luminescent Character of Y_2O_2S∶Eu~(3+)

Effects of Doping Trace Sm~(3+) and Gd~(3+) on Luminescent Character of Y_2O_2S∶Eu~(3+)     

Effect of alkaline metal ions on the photoluminescence properties of Eu~(3+)-doped Ca_3Al_2O_6 phosphors

Ca_3–xAl_2O_6:x Eu~(3+)(0.02≤x≤0.10) and Ca_(2.92)Al_2O_6:0.04Eu~(3+),0.04M~+(M~+=Li~+, Na~+, and K~+) phosphors were prepared by sol-gel method and their photoluminescence properties were investigated. The crystal structure of the annealed Ca_3–xAl_2O_6:x Eu~(3+) and Ca_(2.92)Al_2O_6:0.04Eu~(3+),0.04M~+ phosphors was analyzed with X-ray diffraction(XRD). The size and morphological characteristics of the annealed phosphors were investigated with a field emission scanning electron microscope(FE-SEM). The photoluminescence properties were evaluated with a spectrofluorometer. The phosphors were effectively excited by the light of 396 nm and showed intense red emission at 616 nm, which originated from the 5D_0→7F_2 transition of Eu~(3+). Among the prepared phosphors, the Ca_(2.96)Al_2O_6:0.04Eu~(3+) phosphor showed the strongest emission intensity and the highest color purity. The addition of alkaline metal ions(Li~+, Na~+, and K~+) to Ca_(2.96)Al_2O_6:0.04Eu~(3+) phosphor degraded the emission intensity and color purity.     

Sr_2Al_2SiO_7∶Eu~(2+)发光材料制备及性能研究

采用溶胶凝胶-燃烧还原法在1100℃,p H 3~4的条件下制取了Eu~(2+)掺杂铝硅酸锶发光材料,通过TG-DTA、XRD和荧光光谱分析等方法,研究了材料的结构和发光性能,并对Eu~(2+)不同掺杂浓度下的发光性能进行了对比研究。结果表明,样品干凝胶的分解可以分为熔化、有机物的分解及Sr_2Al_2SiO_7∶Eu~(2+)晶相的生成三个阶段,1100℃所有反应完全;Sr_2Al_2SiO_7∶Eu~(2+)发光材料属于正方晶系晶体结构,其激发光谱是位于峰值344 nm~350nm的宽带谱,发射光谱峰值位于455 nm,最大发射光谱强度为7500 mcd;Eu2+掺杂浓度对其发光性能影响较大,在实验条件下掺杂摩尔浓度为0.04时激发光谱和发射光谱强度均达到最大。     

Sr_(2-x-y)Ca_xMg_yAl_2SiO_7∶Eu~(2+)发光材料的制备及性能研究

采用溶胶凝胶-燃烧法合成Sr_(2-x-y)Ca_xMg_yAl_2SiO_7∶Eu~(2+)稀土长余辉发光材料,通过TG-DTA、XRD、SEM和荧光光谱分析等方法,研究了材料的结构、颗粒形貌和发光性能,并对Ca~(2+)、Mg~(2+)、Eu~(2+)不同掺杂浓度下的发光性能进行了对比研究。结果表明,适量掺杂Ca~(2+)、Mg~(2+)、Eu~(2+)后,基质的晶格结构并未发生变化,为Sr_2Al_2SiO_7晶粒,粒径在1 um~4 um,其激发光谱是位于峰值340 nm~360 nm的宽带谱,发射光谱峰值位于460 nm~480 nm。掺杂Ca~(2+)、Mg~(2+)后发光强度得到提高,镁元素的掺杂可引起发射波长向长波方向移动,而钙元素掺杂可引起发光强度的增大。影响材料发光性能的主要因素是钙,其次是铕,在实验条件下当Ca~(2+)的掺杂量为0.2,Mg~(2+)的掺杂量为0.1,Eu~(2+)的掺杂量为0.04时发光强度为最大,其发射光谱峰值位于469 nm处,最大发射光谱强度达到了8500。     

红色荧光粉BaAl_2Si_2O_8:Eu~(3+),Li~+的制备和发光性能研究

通过高温固相法合成了红色荧光粉系列Ba_(1-x)Al_2Si_2O_8:Eu_x~(3+),Li_(0.03)~+,并系统地研究了该系列荧光粉的晶体结构和发光性质的变化。合成的试样均为BaAl_2Si_2O_8晶体,均单斜晶系,空间群为C2/m(12)。Eu~(3+)取代Ba~(2+)格位进入基质BaAl_2Si_2O_8晶体,造成了基质晶胞参数a,b,c和晶胞体积V相应地减小,只引起了基质晶体结构轻微的畸变。试样的激发光谱位于220 nm~550 nm,由一个宽带激发谱和一组锐线峰带构成,激发光谱中的最强峰为393 nm(~7F_0→~5L_6)。通过393 nm波段对系列试样进行有效激发,收集到发射光谱均位于550 nm~750 nm,且由发射光谱中出现多条锐线峰,在614 nm(~5D_0→~7F_2)处发射峰最强,Eu~(3+)的595 nm(~5D_0→~7F_1)发射峰劈裂产生了590 nm、595 nm和599 nm处的三个分裂峰,而614 nm(~5D_0→~7F_2)发射峰劈裂为614 nm、617 nm、619 nm、622 nm和627 nm处的五个分裂峰,Eu~(3+)取代Ba~(2+)进入基质晶格BaAl_2Si_2O_8中,与其临近的氧配体形成了C2的点群对称性和Eu~(3+)主要占据非反演对称中心格位。系统研究了该系列荧光粉发光性能与掺杂离子Eu~(3+)浓度的关联。研究结果显示,当掺杂离子Eu~(3+)浓度x≤0.03时,荧光粉的发光强度随着掺杂离子Eu~(3+)浓度x的增加而增加,当x0.03时,随x的增加而减小。试样的色坐标不随掺杂离子Eu~(3+)浓度改变而改变;该系列荧光粉浓度淬灭机理为电偶极–电偶极相互作用。     

微波辐射法合成Gd_2O_2SO_4∶Eu~(3+)发光材料及性能研究

以Gd_2O_3、Eu_2O_3和NH_4HSO_4为原料,采用微波辐射法合成了Gd_2O_2SO_4∶Eu~(3+)发光材料。并用X射线衍射仪、扫描电镜、荧光光谱仪对所得发光材料的物相、形貌和发光性能进行了表征。结果表明,微波辐射30 min可以合成纯相Gd_2O_2SO_4∶Eu~(3+)发光材料,晶体结构为正交晶系,与Gd_2O_2SO_4结构相同;其形貌不规则,存在团聚现象;Gd_2O_2SO_4∶Eu~(3+)发光材料呈红光发射,发射光谱由一系列铕离子的~5D_0→~7F_j(j=0,1,2,3,4)能级跃迁的尖峰组成,激发光谱主要由处于200 nm～350 nm的宽激发带和位于397 nm和466 nm的窄激发带组成。     

Preparation,structure, luminescence properties of europium doped zinc spinel structure green-emitting phosphor ZnAl2O4:Eu2+

The Zn_(1-x)Al_2 O_4:xEu~(2+) phosphor powders were synthesized by the solid-state reaction method.The synthesis temperature for ZnAl_2 O_4 was optimized,whereas the phase structure,TEM images,photoluminescence(PL) properties,the concentration quenching mechanism,the fluorescence decay curves,as well as the CIE chromaticity coordinates of the samples were investigated in details.Under the excitation at 379 nm,the phosphor exhibits an asymmetric broad-band green emission with a peak at 532 nm,which is ascribed to the 5 d-4 f transition of Eu2+.When the doping concentration of Eu2+ ions is 0.01,the luminescence intensity of the sample reaches the maximum value.It is further proved that the exchange interaction results in the concentration quenching of Eu2+ in the Zn_(1-x)Al_2 O_4:xEu~(2+) phosphor powders.The thermal quenching property of ZnAl_2 O_4:Eu~(2+)phosphor was investigated and the quantum efficiency(QE) values of the selected Zn_(0.99)Al_2 O_4:0.01 Eu~(2+) phosphor was measured and determined as 54.85%.The lifetime of the optimized sample Zn_(0.99)Al_2 O_4:0.01 Eu~(2+) is 3.0852 μs and the CIE coordinate of the sample was calculated as(0.3323,0.5538) with high-color-purity green emission.All properties indicate that the green-emitting ZnAl_2 O_4:Eu~(2+) phosphor powder has potential application in white LEDs.     

掺杂Ca~(2+)对Sr_2Al_2SiO_7:Eu~(2+)长余辉材料发光性能的影响

本文采用溶胶-凝胶法制备了Sr_(2-x-y)Ca_yAl_2SiO_7:xEu~(2+)(y=0,0.1,0.2,0.3,x=0.04)荧光粉,系统地研究了Ca~(2+)对Sr_2Al_2SiO_7:Eu~(2+)长余辉材料的微观结构和发光性能的影响,以及产生这些影响的机理。通过XRD与SEM分析,发现荧光粉为Sr_2Al_2SiO_7结构且为四方晶系,粒度在70 nm左右。对荧光粉的激发和发射光谱进行了测试,结果表明掺杂Ca~(2+)会使发射峰位置微弱蓝移并当浓度超过0.2%(摩尔分数,下同)后,出现浓度猝灭现象。采用三指数函数模型对余辉衰减曲线进行拟合,发现掺杂Ca~(2+)浓度为0.2%时光子的最大寿命为109 s大于未掺杂Ca~(2+)时的106 s。通过热释光谱测量,估算了其陷阱的深度和密度。分析表明,掺杂Ca~(2+)浓度为0.2%时荧光粉具有较佳的陷阱深度(0.77 eV)与陷阱密度(3.86×10~4(cm~3)~(-1)),表现出优良的余辉性能。     

Fluorescence of Sm~(2+) and Eu~(2+)→Sm~(2+) Energy Transfer in SrB_4O_7

Fluorescence spectra of Sm~(2+)and Eu~(2+)→Sm~(2+)energy transfer were studied in SrB_4O_7.There appearsonly fluorescence from ~5D_0 transition of Sm~2+ at 77 K.The vibronic lines associated with ~5D_0→~7F_0 transitionwere observed.The thermal population to upper states of ~5D_1 and 4f~5d levels from ~5D_0 gives rise to ~5D_1→~7F_J and 5d→4f radiative transitions of Sin~(2+)at higher temperature.     

外场辅助液相法制备红色球形Y_2O_3:Eu~(3+)荧光粉

研究了以尿素为沉淀剂,通过改变加热方式、溶液pH、Eu~(3+)掺杂量及煅烧温度等条件,采用微波辅助液相法制备Y_2O_3:Eu~(3+)红色荧光粉,并对所得荧光粉进行检测分析。结果表明:试验所制备的荧光粉为规整的球形,涂敷性好,可以被近紫外激发光有效激发,发射主峰位于614nm处,归属于Eu~(3+)的~5 D_0→~7 F_2跃迁;该红色荧光粉可应用在白光LED。     

配位体修饰下Eu~(3+)掺杂CaF_2和LaF_3荧光粉发光性能的研究

采用微波法成功合成了具有特殊荧光性质的Eu~(3+)掺杂LaF_3和CaF_2荧光粉。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、光致发光光谱(PL)等分析手段对样品的结构、形貌以及发光性能进行了表征。深入探讨了酒石酸钠、Eu~(3+)掺杂量对合成荧光粉发光性能的影响。实验结果表明,酒石酸钠添加量和Eu~(3+)的掺杂量对其荧光性能具有较大影响;摩尔比的变化使Eu~(3+)从磁偶极跃迁占主导转化为电偶极跃迁占主导,进而使主峰位置从之前的588 nm处变成613 nm处。但没有引起其他峰位置的变化,说明Eu~(3+)进入了LaF_3和CaF_2的晶格之中,而没有其他的变化。     

Emission Spectra and Crystallographic Sites of Eu~(2+) in Ca_8Zn(SiO_4)_4Cl_2

The fluorescent characteristic and emission spectra of Eu~(2+) in the cubic structureCa_8Zn(SiO_4)_4Cl_2 with three kinds of cation sites is reported.The influence of temperature,Eu~(2+) concentra-tion and excitation conditions on fluorescent properties of Eu~(2+) are studied at 77 and 298 K.Thecoordination number of Eu~(2+) at different sites is obtained.The green and red emission bands arise fromEu_(2+) ions locating on eight- and six- coordinated inequivalent sites respectively.     

Enhanced afterglow performance of CaAl_2O_4:Eu~(2+),Nd~(3+) phosphors by co-doping Gd~(3+)

In order to effectively improve the afterglow properties of CaAl_2 O_4:Eu~(2+),Nd~(3+) phosphors,a series of Ca_(0.982-x)Al_2 O_4:0.012 Eu~(2+),0.006 Nd~(3+),xGd~(3+)(x=0,0.012,0.024,0.036,0.048,0.060 mol) phosphors were prepared by a high-temperature solid-phase approach.Crystalline composition and microstructure were characterized by XRD,TEM,HRTEM,and XPS,luminescence properties were systematically analyzed by fluorescence spectra,afterglow decay curves and TL glow curve.Results show that all of Ca_(0.982-x)Al_2 O_4:0.012 Eu~(2+),0.006 Nd~(3+),xGd~(3+)phosphors belong to monoclinic CaAl_2 O_4,without other cystalline phase.The blue emission at 442 nm is observed,which is assigned to the 4 f~65 d→4 f~7 transition of Eu~(2+) ions.Doping with appropriate amount of Gd~(3+) ions(x=0.036 mol) significantly improves the afterglow properties of phosphors,but the excessive doping of Gd~(3+) induces the fluorescent quenching.The doping of moderate Gd3+changes the traps states,the trap depth varies from 0.598 to 0.644 eV and the trap concentration is also greatly improved,thus significantly improving afterglow performance.     

Eu~(2+)- Mn~(2+)共掺T相硅酸盐荧光粉的制备与发光性能

荧光粉是新一代照明器件的重要组成部分, T相碱土金属硅酸盐荧光粉具有独特的晶体结构,表现出优良的抗发光热猝灭性能。将Mn~(2+)引入具有青绿色发光的(Ba_(0.7)Ca_(0.29)Eu_(0.01))_2SiO_4荧光粉,通过Eu~(2+)-Mn~(2+)能量传递可以实现Mn~(2+)的红光发射。通过高温固相反应法制备了具有不同Mn含量的T相碱土金属硅酸盐荧光粉(Ba_(0.7)Ca_(0.29-z)Eu_(0.01)Mn_z)_2SiO_4。X射线衍射(XRD)图谱表明,所合成的样品都为纯相,晶格常数随Mn~(2+)含量增多而减小。通过稳态荧光发射光谱、激发光谱和荧光衰减曲线研究Eu~(2+)-Mn~(2+)能量传递过程,确认其机制为电多极作用,临界距离为3.433 nm。T相(Ba_(0.7)Ca_(0.29-z)Eu_(0.01)Mn_z)_2SiO_4荧光粉在200℃时的发光强度仍可保持室温时的67%～80%,抗发光热猝灭性能优异。通过改变Mn的含量,可以调控Eu~(2+)的蓝光峰与Mn~(2+)的红光峰之间的相对比例,从而实现从冷白光到暖白光的单一基质白光发射。     

Electron Transition of Eu~(2+) and Energy Transfer in Crystals BaFX:Eu~(2+),Eu~(3+) (X=Cl,Br)

In crystals BaFX:Eu~(2+)(X=Cl,Br).there exists configuration interaction between 4f~65d and 4f~65s ex-cited state of Eu~(2+)ion.and it results in the change of relative intensities of d-f and f-f transition.The transition~S_-_2→4f~65d-6s is observed.The variation of F/X atomic ratio between 110/90 and 90/110 does not obvi-ously influence the luminescence of BaFX:Eu~(2-).There is energy transfer between Eu~(2+)(f-f)and Eu~(3+)whichcoexists in the matrices.     

熔盐法制备LaOCl∶Eu~(3+)及其发光性能研究

以共沉淀法制备的La(OH)_3:Eu~(3+)为前驱体,采用KCl-LiCl熔盐法在700℃成功制备了掺杂均匀的LaOCl∶Eu~(3+)的发光材料,SEM及TEM结果显示的LaOCl∶Eu~(3+)粉体的尺寸约为1μm～2μm,且形貌规整,XRD及EDS结果表明Eu~(3+)已较好地掺入了LaOCl晶格,为制备均匀Eu~(3+)掺杂的LaOCl∶Eu~(3+)发光材料提供了一种简便的方法。对比研究了不同比例Eu~(3+)掺杂LaOCl∶Eu~(3+)的发光特性,掺杂Eu~(3+)后LaOCl∶Eu~(3+)具有较优的发光性能,Eu~(3+)的~5D_0→~7F_2跃迁使得LaOCl∶Eu~(3+)具有红光发射特征。激发和发射光谱结果显示6%Eu~(3+)掺杂的LaOCl∶Eu~(3+)具有较强的激发和发射强度。     

Green and red phosphor for LED backlight in wide color gamut LCD

Wide color gamut(WCG) backlight for liquid crystal display(LCD) utilizing white light-emitting diodes(LED) has attracted considerable attention for their high efficiency and color reduction.In this review,recent developments in crystal structure,luminescence and applications of phosphors for wide color gamut LED backlight are introduced.As novel red phosphors,Mn~(4+)activate fluoride and aluminate phosphors are advanced in quantum efficiency,thermal quenching and color saturation for their characteristic spectrum with broad excitation band and linear emission.The crystal structure and fluorescence properties of Mn~(4+)doped fluosilicate,fluorogermanate,fluotitanate,as well as Sr_4 Al_(14)O_(25),CaAl_(12)O_(19) and BaMgAl_(10)O_(17) phosphors are discussed in detail.A serial of narrow-band red-emitting Eu~(2+),Eu~(3+)and Pr~(3+)-doped nitride silicates and molybdate phosphors are also introduced.Rare-earth-doped oxynitride and silicate green-emitting phosphors have attracted more and more attention because of the wide excitation,narrow emission,high quenching temperature,high quantum efficiency,such as β-sialon:Eu~(2+),Ba_3Si_6O_(12)N_2:Eu~(2+),MSi_2O_2N_2:Eu~(2+)(M=Ca,Sr,Ba),y-AlON:Mn~(2+)and Ca_3Sc_2Si_3O_(12):Ce~(3+).All above phosphors demonstrate their adaptability in wide color gamut LCD display.Especially for Mn~(4+)doped fluosilicate red phosphor and β-sialon:Eu~(2+)green phosphor.To achieve an ultra-high color gamut in white LED backlight and against the OLED,innovative narrow-band-emission red and green phosphor materials with independent intellectual property rights are continuously pursed.