Gd_3Al_5O_(12)∶Eu~(3+)柠檬酸盐硝酸盐燃烧法合成及其发光性能研究

采用柠檬酸盐硝酸盐燃烧法,在较低的温度(900℃)下成功地合成单一晶相Gd3Al5O12∶Eu3+发光粉体,紫外激发荧光光谱分析表明,粉体615 nm和593 nm荧光发射源于Eu3+的5D0-7F2和5D0-7F1跃迁.该方法中各工艺条件(如pH值、柠檬酸/金属离子比、煅烧温度)对Gd3Al5O12∶Eu3+发光性能均有影响,通过试验得出了获得最佳发光性能荧光粉体的工艺参数.     

(Y,Gd)Al3(BO3)4∶Ce,Tb的光谱特性及稀土离子间的能量传递

采用高温固相反应合成了(Y,Gd)Al3(BO3)4中掺杂Ce3 和Tb3 的样品,并研究了其结构特性、光谱特性和发光过程中稀土离子间的能量传递.(Y,Gd)Al3(BO3)4属于三角晶系,具有R32的空间群,掺入Ce3 ,Tb3 杂质后晶格结构没有变化.(Y,Gd)Al3(BO3)4∶Ce,Tb的激发光谱由3个宽谱带组成,这3个谱带分别对应于Ce3 的4f-5d跃迁吸收.在该体系中存在Ce3 →Tb3 ,Gd 3 →Tb3 和Gd3 →Ce3 的能量传递,其中Ce3 起敏化剂和中间体的双重作用.     

(Y,Gd)BO_3∶Eu的真空紫外光谱特性

近年来由于等离子体平板显示 (PDP)技术的需要 ,对真空紫外 (VUV)光激发的荧光粉的研究成为发光材料领域中的一个新方向 [1～ 3] .由于技术和实验仪器等方面的原因 [4 ] ,以往人们对稀土发光材料VUV区的研究很少 ,缺乏对其光谱和能级的完整认识 .另外 ,稀土离子 Gd3+在荧光粉的能量传递中具有特殊作用 ,一些含 Gd3+的发光材料在 VUV区发光效率很高 ,例如 ,(Y,Gd) BO3∶ Eu在 VUV区的发光效率比 YBO3∶ Eu提高了 2 0 % ,比 Y2 O3∶ Eu提高了 1 .8倍 ,与其它红粉相比更具有实际应用价值 [4 ,5] .但目前对于 (Y,Gd) BO3∶ Eu的研…     

氮化镓发光二级管蓝光转换材料的合成和发光性质

合成了Ce3＋掺杂的稀土石榴石结构复合氧化物体系(Y1-xGdx)3Al5O12、(Y1-xLux)3Al5O12、(Y1-xLax)3Al5O12、(Y1-xYbx)3Al5O12和(Y1-xTbx)3Al5O12.重点研究了(Y1-xGdx)3Al5O12:Ce3＋和(Y1-xLux)3Al5O12:Ce3＋两个体系的晶体结构和发光性质.这些体系都具有立方石榴石结构.(Y1-xGdx)3Al5O12:Ce3＋体系随Gd取代Y,晶胞参数略有增加.荧光光谱的发射波长随Gd浓度增加发生红移,当x=0.5时发射波长达到最大值（560 nm）,并不再随Gd含量增加而变化. (Y1-xLux)3Al5O12:Ce3＋的晶胞参数随 Lu取代Y而减小,但均保持了立方石榴石结构.荧光光谱的发射波长随Lu3＋的增加向短波方向移动,Lu3Al5O12:Ce3＋的发射波长的峰值为520 nm,体系的蓝移量是20 nm.利用分离发光中心的位形坐标模型对波长的移动作了定性解释.这两个体系的发射波长的可调节特性,对改善与氮化镓发光二极管(LED)匹配的蓝光转换材料的色坐标、色温等显色性质具有重要意义.     

YAG∶Ce体系中稀土离子掺杂对Ce3+的光谱性能的影响

采用高温固相法合成了一系列的(Y0.95Ln0.01Ce0.04)3Al5O12(简称YAG∶Ce,Ln),系统地研究了此体系中的Ln3 对Ce3 的发光强度的影响.结果表明,在YAG∶Ce的体系中,La3 ,Gd3 ,Lu3 等光学透明离子的少量掺杂对Ce3 的发光强度的影响不大;掺入少量的Pr3 ,Sm3 ,Tb3 ,Dy3 ,Ho3 ,Er3 ,Tm3 等稀土离子,由于它们的能级与Ce3 的能级有交叠,使它们之间存在着竞争吸收或能量转移,对Ce3 的发光有较明显的变化,其中,Pr3 和Sm3 的掺入使其在红光区有发射峰,可以增加YAG∶Ce的红色成分以提高显色性;Nd3 ,Eu3 和Yb3 对Ce3 的发光有严重的猝灭作用.     

氯化稀土与丙氨酸配合行为的研究

用半微量相平衡方法研究了SmCl~3-Ala-H~2O三元体系在25℃时的溶解度。结果表明体系中形成了两种配合物: Sm(Ala)~2Cl~3.3H~2O和Sm(Ala)~3Cl~3.3H~2O,合成了RE(Ala)~3Cl~3.3H~2O(RE=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy),RE(Ala)~2Cl~3.nH~2O(RE=La, Ce, Pr, Nd, Sm, n=3; RE=Ho, Yb,Y, n=4)与RE(AlA)Cl~3.6H~2O(RE=Eu, Gd,Tb, Dy, Ho, Yb, Y)二十四种固体配合物, 用化学分析、IR、UV、X射线分析及TG-DTG对配合物进行了表征, 发现了RECl~3与Ala形成配合物的规律性。     

YAG∶Ce体系中稀土离子掺杂对Ce3+的光谱性能的影响

采用高温固相法合成了一系列的(Y0.95Ln0.01Ce0.04)3Al5O12(简称YAG∶Ce,Ln), 系统地研究了此体系中的Ln3+对Ce3+的发光强度的影响. 结果表明, 在YAG∶Ce的体系中, La3+, Gd3+, Lu3+等光学透明离子的少量掺杂对Ce3+的发光强度的影响不大; 掺入少量的Pr3+, Sm3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+等稀土离子, 由于它们的能级与Ce3+的能级有交叠, 使它们之间存在着竞争吸收或能量转移, 对Ce3+的发光有较明显的变化, 其中, Pr3+和Sm3+的掺入使其在红光区有发射峰, 可以增加YAG∶Ce的红色成分以提高显色性; Nd3+, Eu3+和Yb3+对Ce3+的发光有严重的猝灭作用.     

(Y,Gd)BO3:Eu的真空紫外光谱特性

近年来由于等离子体平板显示(PDP)技术的需要,对真空紫外(VUV)光激发的荧光粉的研究成为发光材料领域中的一个新方向[1～3]. 由于技术和实验仪器等方面的原因[4], 以往人们对稀土发光材料VUV区的研究很少, 缺乏对其光谱和能级的完整认识. 另外, 稀土离子Gd3+在荧光粉的能量传递中具有特殊作用, 一些含Gd3+的发光材料在VUV区发光效率很高, 例如, (Y,Gd)BO3:Eu在VUV区的发光效率比YBO3:Eu提高了20%, 比Y2O3:Eu提高了1.8倍, 与其它红粉相比更具有实际应用价值[4,5]. 但目前对于(Y,Gd)BO3:Eu的研究主要集中在紫外可见区[6], 因此, 深入研究(Y,Gd)BO3:Eu的真空紫外光谱特性, 对于发展PDP技术具有重要意义.     

RE(ClO_4)_3·nH_2O与丙氨酸、咪唑配合物的合成、表征及生物活性

研究了 9种RE(ClO4) 3·nH2 O与Ala(丙氨酸 CH3CHNH2 COOH)及Im(咪唑 )在甲醇中的配位作用。用化学分析、元素分析、IR、UV、FS光谱及X射线粉末衍射对配合物进行了表征。确定了其组成为RE(Ala) 2 Im (ClO4) 3·nH2 O (RE =Ce ,Sm ,n =2 ;RE =Pr ,Nd ,Eu ,Gd ,Tb ,Yb ,n =1)及La(Ala) 3Im(ClO4) 3·3H2 O。并结合1 HNMR及TG DTG进一步研究了新配合物的配位行为及热分解机制。生物活性测定结果表明 ,该类配合物尤其是重稀土配合物具有明显的广谱抑菌作用。     

高温固相法合成长余辉发光材料Sr_(0.96)Al_2O_4:Eu_(0.02)~(2+),Dy_(0.02)~(3+)

以高温固相法合成了Sr0.96Al2O4:Eu2+0.02,Dy3+0.02长余辉发光材料,其激发光谱和发射光谱均为宽带谱,激发光谱为300～480nm,具有从紫外到蓝绿光波段能量的吸收范围.随着稀土元素Eu2+掺杂量的增加,发光强度逐渐增强,当Eu2+掺杂量达到2(mol)%时,材料的发光强度最大.辅助激活剂Dy3+的添加能显著改善材料的余辉性能.Sr0.96Al2O4:Eu2+0.02,Dy3+0.02在25W日光灯激发30min后,黑暗环境中余辉长达3h.     

Structure Refinement and Two-Center Luminescence of Ca(3)La(3)(BO(3))(5):Ce(3+) under VUV-UV Excitation

A series of Ca(3)La(3(1-x))Ce(3x)(BO(3))(5) phosphors were prepared by a high-temperature solid-state reaction technique. Rietveld refinement was performed using the powder X-ray diffraction (XRD) data, which shows occupation of Ce(3+) on both Ca(2+) and La(3+) sites with a preferred location on the La(3+) site over the Ca(2+) site. The prepared samples contain minor second phase LaBO(3) with contents of ～0.64-3.27 wt % from the Rietveld analysis. LaBO(3):1%Ce(3+) was prepared as a single phase material and its excitation and emission bands were determined for identifying the influence of impurity LaBO(3):Ce(3+) luminescence on the spectra of the Ca(3)La(3(1-x))Ce(3x)(BO(3))(5) samples. The luminescence properties of Ca(3)La(3(1-x))Ce(3x)(BO(3))(5) samples under vacuum ultraviolet (VUV) and UV excitation were investigated, which exhibited two-center luminescence of Ce(3+), assigned to the Ce(1)(3+) center in the La(3+) site and Ce(2)(3+) center in the Ca(2+) site, taking into account the spectroscopic properties and the Rietveld refinement results. The influences of the doping concentration and the excitation wavelength on the luminescence of Ce(3+) in Ca(3)La(3(1-x))Ce(3x)(BO(3))(5) are discussed together with the decay characteristics.     

掺杂铕和铽的卤硼酸盐荧光体的制备及光谱特征

采用高温固相法在空气中合成了一系列掺杂稀土离子的卤硼酸盐荧光体, 研究了其发光性质和基质组成对稀土离子共掺杂的荧光体发光性质的影响. 研究结果表明, 在Eu3+和Tb3+共掺杂的体系中存在电子转移, 因此出现了Eu3+, Eu2+和 Tb3+共存于同一基质共同发射的现象. Ce3+对Eu2+和Tb3+具有敏化作用, 可增强其发射强度. 基质的组成对稀土离子的发射峰位和发射强度有明显影响.     

Combinatorial search for green and blue phosphors of high thermal stabilities under UV excitation based on the K(Sr1-x-y)PO4:Tb3+ xEu2+y system

The present investigation aims at the synthesis of KSr 1-x-y PO 4:Tb(3+) x Eu(2+) y phosphors using the combinatorial chemistry method. We have developed square-type arrays consisting of 121 compositions to investigate the optimum composition and luminescence properties of KSrPO 4 host matrix under 365 nm ultraviolet (UV) light. The optimized compositions of phosphors were found to be KSr 0.93PO 4:Tb(3+) 0.07 (green) and KSr 0.995PO 4:Eu(2+) 0.005 (blue). These phosphors showed good thermal luminescence stability better than commercially available YAG:Ce at temperature above 200 degrees C. The result indicates that the KSr 1-x-y PO 4:Tb(3+) x Eu (2+)y can be potentially useful as a UV radiation-converting phosphor for light-emitting diodes.     

Luminescence investigation on ultraviolet-emitting rare-earth-doped phosphors using synchrotron radiation

Three series of new ultraviolet-emitting Ca(9)Y(PO(4))(7):Ln(3+) (Ln = Ce, Gd, Pr) phosphors were synthesized, and their luminescence was investigated. Under vacuum ultraviolet excitation Ca(9)Y(PO(4))(7):Ce(3+) phosphors emit UVA light with one broad emission centered at 346 nm, on account of the 5d(1) → 4f(1) transition of Ce(3+) ions; the optimal doping concentration of these phosphors is 0.2 mol. Ca(9)Y(PO(4))(7):Gd(3+) phosphors show a strong 4f(7) → 4f(7) transition and a sharp UVB emission band at 312 nm; the optimal doping concentration of these phosphors is 0.7 mol. The PL spectra of Ca(9)Y(PO(4))(7):Pr(3+) show two broad UVC emission bands centered between 230 and 340 nm, owing to the 4f(1)5d(1) → 4f(2) transition of Pr(3+) ions; the optimal doping concentration of these phosphors is 0.2 mol. Under 172 nm excitation, we found that the luminescence intensity of the UVA-emitting Ca(9)Y(PO(4))(7):0.2Ce(3+) is 0.3675 times that of BaSi(2)O(5):0.05Pb(2+), that of the UVB-emitting Ca(9)Y(PO(4))(7):0.7Gd(3+) is 1.7 times that of YAl(3)(BO(3))(4):0.25Gd(3+), and that of the UVC-emitting Ca(9)Y(PO(4))(7):0.2Pr(3+) is 1.5 times that of LaPO(4):0.1Pr(3+). The thermal stability investigation indicated that the luminescence decay was only 9.2%, 18.2%, and 10.3% for Ca(9)Y(PO(4))(7):0.2Ce(3+), Ca(9)Y(PO(4))(7):0.7Gd(3+), and Ca(9)Y(PO(4))(7):0.2Pr(3+) at 250 °C relative to that at ambient temperature, respectively. The Ca(9)Y(PO(4))(7):Ln(3+) (Ln = Ce, Gd, Pr) phosphors exhibit high emission efficiency and excellent thermal stability.     

Ce1-xNixO2/Al2O3/FeCrAl催化剂的制备及其甲烷催化燃烧性能

以FeCrA l合金薄片为基体,A l2O3为过渡载体,Ce1-xN ixO2(x=0.1-0.3)、CeO2和N iO为活性组分,制备了Ce1-xN ixO2/A l2O3/FeCrA l、CeO2/A l2O3/FeCrA l和N iO/A l2O3/FeCrA l金属基整体式催化剂,在固定床微型反应器中评价了催化剂的甲烷催化燃烧性能,用SEM、XRD、TPR等方法对催化剂的物相、表面形貌和氧化还原性进行了表征.结果表明,Ce1-xN ixO2在催化剂表面的分散性比CeO2和N iO要好;Ce1-xN ixO2/A l2O3/FeCrA l(x=0.1-0.3)催化剂具有好的催化活性和高温稳定性,CeO2/A l2O3/FeCrA l和N iO/A l2O3/FeCrA l催化剂有好的初活性但高温稳定性较差;活性组分与A l2O3和FeCrA l金属基体之间存在较强的相互作用.     

Controlling disorder in host lattice by hetero-valence ion doping to manipulate luminescence in spinel solid solution phosphors

Phosphor materials have been rapidly developed in the past decades. Developing phosphors with desired properties including strong luminescence intensity and long lifetime has attracted widespread attention. Herein, we show that hetero-valence ion doping can serve as a potent strategy to manipulate luminescence in persistent phosphors by controlling disorder in the host lattice. Specifically, spinel phosphor Zn(Ga_(1-x)Zn_x)(Ga_(1-x)Ge_x)O_4:Cr is developed by doping ZnGa_2O_4:Cr with tetravalent Ge~(~(4+)).Compared to the original ZnGa_2O_4:Cr, the doped Zn(Ga_(1-x)Zn_x)(Ga_(1-x)Ge_x)O_4:Cr possesses significantly enhanced persistent luminescence intensity and prolonged decay time. Rietveld refinements show that Ge~(4+)enters into octahedral sites to substitute Ga~(3+), which leads to the co-substitution of Ga~(3+) by Zn~(2+) for charge compensation. The hetero-valence substitution of Ga~(3+) by Ge~(4+)and Zn~(2+) enriches the charged defects in Zn(Ga_(1-x)Zn_x)(Ga_(1-x)Ge_x)O_4:Cr, making it possible to trap large amounts of charge carriers within the defects during excitation. Electron paramagnetic resonance measurement further confirms that the amount of Cr~(3+) neighboring charged defects increases with Ge~(4+)doping. Thus charge carriers released from defects can readily combine with the neighboring Cr~(3+) to produce bright persistent luminescence after excitation ceases. The hetero-valence ion doping strategy can further be employed to develop many other phosphors and contributes to lighting, photocatalysis and bioimaging.     

Revision of structural properties of GdBO3 nanopowders doped with Eu3+ ions through spectroscopic studies

Monoclinic Gd(1-x)Eu(x)BO(3) nanopowders were successfully synthesized using a modified Pechini method. The crystal structure of the prepared materials was revised and confirmed using several techniques such as: IR, XRD, TEM, Raman spectroscopy and EDX analysis. The obtained material was comprised of particles, consisting of parts with the average size 350 nm. The luminescence properties of the prepared phosphors with different concentrations of Eu(3+) ions were characterized by excitation and emission spectra and its kinetic decay. The Judd-Ofelt parameters (Ω(2), Ω(4)), quantum efficiency, η, and chromaticity coordinates were also calculated.     

磷灰石结构荧光粉Ba10(PO4)6F2:Ce3+,Tb3+的合成、发光和能量传递

采用高温固相法合成了系列Ce~(3+)和Ce~(3+)/Tb~(3+)激活的具有磷灰石结构荧光粉Ba_(10)(PO_4)_6F_2。用X射线衍射(XRD)、扫描电镜(SEM)、激发和发射(PLE和PL)光谱对样品进行了表征分析。研究结果表明:所合成的荧光粉Ba_(10)(PO_4)_6F_2∶Ce~(3+),Tb~(3+)具有氟磷灰石结构,样品微观呈现不规则形貌。荧光粉Ba10-x(PO4)6F2∶x Ce~(3+)的相对发射强度随着x增加而增强,当x=0.09时,荧光强度达到最大。荧光粉Ba_(10)(PO_4)_6F_2∶Ce~(3+),Tb~(3+)的激发光谱为240～330 nm的宽带,发射光谱呈现出Ce~(3+)的5d→4f跃迁紫外光(335和358 nm)发射和Tb~(3+)的4f→4f跃迁绿光(542 nm)发射。光谱特性表明,发光过程中存在Ce~(3+)→Tb~(3+)能量传递,能量传递效率可以达到60%。计算Ce~(3+)和Tb~(3+)的临界距离为0.79 nm,能量传递机理是偶极-偶极交互作用。此外,详细论述了Ce~(3+)和Tb~(3+)之间的能量传递和发光的过程。通过调节Tb~(3+)的掺杂浓度,对荧光粉发光色坐标与Tb~(3+)的掺杂浓度之间的关系也进行了研究,随着Tb~(3+)的掺杂量从0增加0.52,荧光粉Ba_(10)(PO_4)_6F_2∶Ce~(3+),Tb~(3+)的发射光谱色坐标可以从(0.149 4,0.045 1)蓝色区变化到(0.280 1,0.585 3)绿色区。