Gd3Ga5O12:Ag薄膜电致发光材料的制备及其发光性质

研究了Gd₃Ga₅O₁₂:Ag材料的制备及其发光性质.Gd₃Ga₅O₁₂:Ag材料通过固相反应法制得,采用X射线衍射法分 析了材料的结晶度及成分.用电子束蒸发将该材料制备成交流的薄膜电致发光器件,得到了 较好的蓝紫色发光,发光峰分别位于397和467nm.通过对材料的光致发光和激发光谱的研究 和比较,得出397和467nm分别来自于氧空位和Ag⁺的发光.     

Eu3+掺杂Gd2W2O9和Gd2（WO4）3纳米荧光粉发光性质研究

采用共沉淀法制备了不同Eu3+掺杂浓度的Gd2W2O9和Gd2(WO4)3纳米发光材料.通过对纳米材料样品的X射线衍射谱(XRD)和场发射扫描电镜(FE-SEM)照片的观察和分析,对样品的结构和形貌进行了表征.测量了各样品的发射光谱、激发光谱,计算了各样品的部分J-O参数和Eu3+5D0能级量子效率,绘制了不同基质中Eu3+发光的浓度猝灭曲线,对Eu3+掺杂的Gd2W2O9和Gd2(WO4)3纳米发光材料的光致发光性质进行了研究.实验结果证明,与较常见的Gd2(WO4)3:Eu一样,Gd2W2O9:Eu中Eu3+5D0→7F2跃迁的红色发光也能被395nm和465nm激发光有效激发,具有近紫外(蓝光)相对激发效率高,猝灭浓度大的优点,有潜力成为高效的近紫外(蓝光)激发白光LED用红色荧光粉材料.     

阳离子取代对Lu_3Ga_5O_(12)∶Tb~(3+)晶体结构与发光性能的影响

采用高温固相法制备了Lu3Ga5O12:Tb3+体系荧光粉,研究了Y3+、Gd3+和Al3+离子分别取代Lu3+和Ga3+离子后对荧光粉晶体结构和发光性能的影响。结果表明,Lu3Ga5O12∶Tb3+具有石榴石结构,激发光谱由A、B两个宽激发带及一些窄谱峰构成,分别归属于Tb3+的4f8→4f75d1和4f8→4f8的电子跃迁。紫外激发下的发射光谱对应于Tb3+5D4→7FJ和5D3→7FJ跃迁。对于(Lu,Y)3Ga5O12∶Tb3+体系,随着Y3+浓度的增加,晶格膨胀,A、B宽带红移,带间距缩小,激发与发射强度提高。对于(Lu,Gd)3Ga5O12∶Tb3+体系,当Gd3+浓度低于0.75时,随着Gd3+浓度的增加,荧光粉性能变化与引入Y3+时情况相似,并更为显著;实验中观察到Gd3+→Tb3+能量传递现象。对于Lu3(Ga,Al)5O12∶Tb3+体系,随着Al3+含量的增加,晶格收缩,A、B宽带红移,带间距扩大,激发与发射强度提高。阳离子的半径差异及其引起的Tb3+晶场环境的变化是影响荧光粉性能的主要原因。     

Tb3+离子在固溶体(Y0.9Gd0.1)2O2S和(Gd0.9La0.1)2O2S中的发光

用稀土氧化物硫化法合成了固溶体发光材料(Y0.9Gd0.1)2O2S:Tb和(Gd0.9La0.1)2O2S:Tb,并且用阴极射线和254nm紫外线两种激发方式测试了它们的发光性能.研究了固溶体(Y0.9Gd0.1)2O2S:Tb和(Gd0.9La0.1)2O2S:Tb中Tb3+离子5D3——7FJ和5D4——7FJ的能级跃迁强度随Tb3+离子浓度而变化的关系,以及它们的发光色度随激活剂Tb3+离子浓度的变化,探讨了Tb3+离子的浓度猝灭机理.     

Er3+/Yb3+共掺Gd3Sc2Ga3O12晶体的上转换发光

研究了提拉法生长的Er3+/Yb3+:Gd3Sc2Ga3O12和Er3+:Gd3Sc2Ga3O12晶体在室温下320-1700 nm范围的吸收光谱和500-750 nm范围内的上转换荧光谱,同时对其上转换荧光的可能发生机制、途径以及上转换过程可能对Er3+的2.8 μm波段激光振荡产生的影响进行了分析和讨论.结果表明:Yb3+的敏化显著地增强了晶体在966 nm附近的吸收能力,大幅度加宽了晶体在该处的吸收带宽.在940 nm激光的激发下,Er3+/Yb3+:Gd3Sc2Ga3O12中的上转换荧光强度明显强于Er3+:Gd3Sc2Ga3O12中的上转换荧光强度,表明Yb3+与Er3+之间存在高效率的能量传递,其主要上转换机制可能为Yb3+-Er3+,Er3+-Er3+能量传递.     

Gd2O3:Eu3+纳米晶的燃烧合成及光致发光性质

采用柠檬酸作燃烧剂用燃烧合成法制备了Gd2O3:Eu3+纳米晶.用X射线衍射仪(XRD)、高分辨透射电子显微镜(HRTEM)和荧光分光光度计等对Gd2O3:Eu3+纳米晶的结构、形貌和发光性能进行了分析.结果表明:不同柠檬酸与稀土离子配比(C/M)制备的样品经800℃退火1 h后,均得到了纯立方相的Gd2O3:Eu3+纳米晶,晶粒尺寸约为30 nm,尺寸分布较窄,其中以C/M=1.0时制备的纳米晶结晶性最好,发光强度最大.Gd2O3:Eu3+纳米晶主发射峰位置均在612 nm处(5D0→7F2跃迁),激发光谱中电荷迁移态发生红移,观察到Gd3+向Eu3+的有效能量传递.对柠檬酸与稀土离子配比(C/M)对结晶度、发光性质等的影响也进行了分析和讨论.     

Na3GdSi2O7:Tb3+荧光粉发光特性及Gd3+→Tb3+之间的能量传递

采用高温固相法合成了Na3Gd1-xTbxSi2O7(x=0.01,0.02,0.04,0.06,0.08,0.1)系列荧光粉。研究了荧光粉的真空紫外-可见发光光谱和荧光寿命,讨论了Tb3+在扭曲八面体结构(标示为Gd(1)3+)和正三棱柱构型(标示为Gd(2)3+)两种格位中的最低5d轨道能级。同时研究了Gd3+→Tb3+之间无辐射能量传递速率K和无辐射能量传递效率η。研究结果表明:Tb3+在Gd(1)3+格位中的最低允许跃迁和禁戒跃迁的5d轨道能级分别位于235 nm和280 nm,在Gd(2)3+格位中的最低允许跃迁和禁戒跃迁的5d轨道能级分别位于224nm和256 nm。随着Tb3+浓度的增加,能量传递效率及速率显著增大,说明在Na3Gd1-xTbxSi2O7中存在有效的Gd3+-Tb3+能量传递。     

Gd2（WO4）3∶Eu3+,Sm3+纳米晶的制备及Sm3+对Eu3+特征发射的敏化作用

采用共沉淀法分别制备了Eu3+、Sm3+单掺和共掺Gd2(WO4)3纳米发光材料,对所制备的纳米发光材料的结构和发光特性进行了研究。结果表明:所得样品为Gd2(WO4)3的底心单斜结构,Eu3+的摩尔分数为20%时,Gd2(WO4)3∶20%Eu3+的发光最强。Sm3+对Eu3+有敏化作用,使Eu3+的5D0→7F2发射明显增强。用464 nm的光激发时,Sm3+对Eu3+的敏化作用强于用395 nm的光激发。Sm3+的摩尔分数为5%时,样品Gd2(WO4)3∶20%Eu3+,5%Sm3+的5D0→7F2发射强度最大。Sm3+的掺入使监测Eu3+的5D0→7F2跃迁的激发光谱强度明显增大,且拓宽了可被LED有效激发的波长范围。在405 nm和440 nm波长的光激发下,也可以明显观察到样品Gd2(WO4)3∶20%Eu3+,5%Sm3+中Eu3+的5D0→7F2跃迁。     

白光LED用红色荧光粉α-Gd2(MoO4)3:Eu的制备及其发光性能研究

以Gd2O3,MoO3,Eu2O3为原料,采用传统的高温固相反应方法制备了一种新的白光LED用红色荧光粉材料α相Gd2(MoO4)3:Eu.利用XRD,SEM,激发和发射光谱对其进行了研究.分析了助熔剂和激 .活剂对样品的晶体结构,表面形貌和发光性能的影响.结果表明这种荧光粉可以被近紫外光(395 nm)和蓝光(465 nm)有效激发,发射峰值位于613 nm(Eu3 离子的5D0→7F2跃迁)的红光,激发波长与目前广泛使用的蓝光和紫外光LED芯片相符合.因此,三价Eu离子激活的α相Gd2(MoO4)3是一种可能应用在白光LED上的红色荧光粉材料.     

LiBaPO4:Eu3+材料的制备及发光特性

采用高温固相法制备了LiBaPO4:Eu3+红色发光材料,研究了Eu3+掺杂浓度、电荷补偿剂等对材料发光性质的影响.结果显示,在401nm近紫外光激发下,材料呈多峰发射,分别由Eu3+的5Do→7FJ(J=0,1,2,3,4)能级跃迁产生,主峰位于619 nm;监测619 nm发射峰,所得激发光谱由O2- →Eu3+电...     

绿色荧光粉Gd2Ba3B3O12:Tb3+的发光性能研究

采用高温同相法制备了一系列Gd<,2>Ba<,3>B<,3>O<,12>:Tb<'3+>绿色荧光粉,借助X射线粉末衍射仪(XRD)、真空紫外光谱和荧光光谱仪(VUV-UV)对样品的物相、发光性能进行了表征.结果表明,Tb<'3+>作为发光中心全部进入到基质Gd<,2>Ba<,3>B<,3>O<,12>的品格中并占据Gd...     

Improvement in electroluminescence performance of n-ZnO/Ga_2O_3 /p-GaN heterojunction light-emitting diodes

n-ZnO/p-GaN heterojunction light-emitting diodes with and without a Ga2O3 interlayer are fabricated. The electroluminescence （EL） spectrum of the n-ZnO/p-GaN displays a single blue emission at 430 nm originating from GaN, while the n-ZnO/Ga2O3/p-GaN exhibits a broad emission peak from ultraviolet to visible. The broadened EL spectra of n-ZnO/Ga2O3/p-GaN are probably ascribed to the radiative recombination in both the p-GaN and n-ZnO, due to the larger electron barrier （ΔEC=1.85 eV） at n-ZnO/Ga2O3 interface and the much smaller hole barrier （ΔEV=0.20 eV） at Ga2O3/p-GaN interface.     

铬、钕双掺钆镓石榴石(Cr~(4+),Nd~(3+))∶Gd_3Ga_5O_(12)激光晶体光学性能的研究

用提拉法生长了掺铬、钕的钆镓石榴石(Cr4+,Nd3+∶GGG)自调Q激光晶体。报道了室温下的吸收光谱和荧光光谱特性。分析了Cr离子浓度对光谱性质的影响。比较了Cr4+∶GGG,Nd3+∶GGG和(Cr4+,Nd3+)∶GGG晶体吸收光谱的关系。测量了(Cr4+,Nd3+)∶GGG晶体和Nd3+∶GGG晶体的荧光寿命,它们分别是33μs和250μs。实验表明,(Cr4+,Nd3+)∶GGG晶体是一种非常有潜力的自调Q激光晶体,可以实现大功率激光器的小型化和全固态化。     

Surface thermometry in combustion diagnostics by sputtered thin films of thermographic phosphors

The accuracy and robustness of the thermographic phosphors (TP) technique relies in the use of coatings with low thickness, high-intensity luminescent emission and high adhesion to the surfaces. Sputter deposition has been evaluated as an alternative for coating preparation of TPs for surface thermometry in combustion diagnostics. Thin films of \(\hbox {Gd}_{3}\hbox {Ga}_{5}\hbox {O}_{12}{:}\hbox {Cr}^{3+}\) have been deposited on fused silica and stainless steel substrates by radio frequency magnetron sputtering. Physical, chemical, and temperature-dependent luminescence properties of the phosphor films have been evaluated using X-ray diffraction, X-ray photoelectron spectroscopy and laser-induced luminescence, respectively. The results showed that the luminescence features of the thin films must be activated by heat treatment after sputter deposition. The \(\hbox {Gd}_{3}\hbox {Ga}_{5}\hbox {O}_{12}{:}\hbox {Cr}^{3+}\) films exhibited appropriate temperature sensitivity with adequate precision of the temperature determination, proving to be suitable for pointwise (0D) surface thermometry. An evaluation of the spatial homogeneity of the luminescence properties, which has not been yet addressed in the literature for thin films of TPs, revealed that thin \(\hbox {Gd}_3\hbox {Ga}_5\hbox {O}_{12}{:}\hbox {Cr}^{3+}\) films deposited on fused silica can be used for spatially resolved surface thermometry while those deposited on stainless steel require improvements to overcome spatial inhomogeneities of the luminescence lifetimes.     

Performance of a low-loss pulsed-laser-deposited Nd:Gd(3) Ga(5)O(12) waveguide laser at 1.06 and 0.94 mum

We report the laser performance of a low-propagation-loss neodymium-doped Gd(3)Ga(5)O(12) (Nd:GGG) waveguide fabricated by pulsed-laser deposition. An 8- mum -thick crystalline Nd:GGG film grown upon an undoped Y(3)Al(5)O(12) substrate lases at 1.060 and 1.062 microm when pumped by a Ti:sapphire laser operating at 740 or 808nm.Using a 2.2% output coupler, we observed a 1060-nm laser threshold of 4mW and a slope efficiency of 20%. Laser action was also achieved, for what we believe is the first time in Nd:GGG, on the quasi-three-level 937-nm transition. With a 2% output coupler at this wavelength a laser threshold of 17mW and a 20% slope efficiency were obtained. This demonstration of low propagation loss combined with the fact that these waveguides have a very high numerical aperture (0.75) makes pulsed-laser-deposited thin films attractive for high-power diode-pumped devices.     

High performance latching-type luminescent magneto-optical photonic crystals

We report the properties of one-dimensional heteroepitaxial all-garnet magneto-optical photonic crystals (MOPCs) composed of alternating quarter-wavelength layers of diamagnetic Sm(3)Ga(5)O(12) and MO-active Bi(2.97)Er(0.03)Al(0.5)Ga(0.5)O(12) garnets rf-magnetron sputtered on Gd(3)Ga(5)O(12) (111) substrate. Substitution of ferric ions by aluminum and gallium improved transparency and induced perpendicular anisotropy in pure bismuth iron garnet. As a result, photonic crystals owned a record high magneto-optical quality and a latching-type (magnetic remnant) Faraday rotation (FR). At the resonance wavelengths 775(640) nm, a specific FR(θ)(F)=-14.1(14.8) deg/μm and MO-quality factor Q=99.3(46.2) deg represent the highest MOPC performance achieved so far.     

Planar spin fluctuations with a quadratic thermal dependence rate in spin liquid Gd3Ga5O12

The spin liquid properties of Gd3Ga5O12 have been examined using 155Gd M?ssbauer spectroscopy down to 0.027 K. Information has been obtained concerning both the directional properties of the short range correlated moments and the thermal dependence of their spin fluctuation rates. Each Gd3+ spin (S=7/2) is found to be confined to a plane and its fluctuation rate decreases from approximately 2.8 x 10(9) s(-1) at 0.4 K to approximately 0.03 x 10(9) s(-1) at 0.09 K following a close-to-quadratic thermal dependence.     

Transition to a virtually incompressible oxide phase at a shock pressure of 120 GPa (1.2 Mbar): Gd3Ga5O12

Cubic, single-crystal, transparent Gd(3)Ga(5)O(12) has a density of 7.10 g/cm(3), a Hugoniot elastic limit of 30 GPa, and undergoes a continuous phase transition from 65 GPa to a quasi-incompressible (QI) phase at 120 GPa. Only diamond has a larger Hugoniot elastic limit. The QI phase of is more incompressible than diamond from 170 to 260 GPa. Electrical conductivity measurements indicate the QI phase has a band gap of 3.1 eV. Gd(3)Ga(5)O(12) can be used to obtain substantially higher pressures and lower temperatures in metallic fluid hydrogen than was achieved previously by shock reverberation between Al(2)O(3) disks.     

An organic electroluminescent device made from a gadolinium complex

A gadolinium ternary complex, tris(1-phenyl-3-methyl-4-isobutyryl-5-pyrazolone) (phenanthroline) gadolinium [Gd(PMIP)₃(Phen)] was synthesized and used as a light emitting material in the organic electroluminescent (EL) devices. The triple layer device with a structure of indium tin oxide (ITO)/N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD) (20 nm)/Gd(PMIP)₃(Phen) (80 nm)/2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline (bathocuproine or BCP) (20 nm)/Mg: Ag(200 nm)/Ag(100 nm) exhibited green emission peaking at 535 nm. A maximum luminance of 230 cd/m² at 17 V and a peak power efficiency of 0.02 lm/w at 9 V were obtained.