温度和浓度对分散在SiO2中Y2O3:Eu3+纳米材料发光的影响

讨论了分散在SiO2中的Y2O3：Eu纳米发光材料在不同浓度和不同灼烧温度下光谱的变化规律,在室温紫外激光波长激发下不同灼烧温度下样品的发射光谱。从光谱上看到在一定浓度下随着灼烧温度的升高发光变强,而且在一定温度下随浓度提高发光变强。尤其在^5D0→^7F0跃迁谱线的强度明显高于^5D0→^7F2的电偶极跃迁强度,并分析了原因。探讨了合理的掺杂浓度和灼烧温度,并测量了Y2O5：Eu质量分数为5％时,灼烧温度在1300℃时的激发光谱和格位选择激发光谱。样品平均粒径50nm,得到在不同波长激发下的^5D0→^7F0和^5D0→^7F2选择激发光谱。分析认为Eu^3 存在着4种格位,并对其进行了初步的分析讨论。     

稀土离子(Eu3+,Tb3+,Ce3+)掺杂ZnAl2O4/SiO2微晶玻璃的制备与发光性能

采用凝胶法分别制备出4.5ZnO-5.5Al2 O3-90SiO2 (ZAS)以及ZAS∶ RE3+(RE=Eu,Tb,Ce)透明微晶玻璃.利用X射线衍射仪(XRD)、透射电子显微镜(TEM)和荧光光谱仪(PL)等测试手段,研究了稀土离子掺杂浓度对ZAS微晶玻璃的结构和发光性能的影响.XRD结果表明,ZAS∶ RE3+(RE=Eu,Tb,Ce)微晶玻璃包含ZnAl2 O4晶相和SiO2非晶相,ZnAl2 O4平均晶粒尺寸约为30 nm,稀土离子的掺杂没有显著改变原来的ZnAl2O4晶体结构.TEM结果表明,900℃时ZnAl2O4从ZAS体系中析出.PL光谱显示,Eu3+存在5 D0→7F2跃迁,ZAS∶Eu3+在611 nm处发出强烈的红色光;由于Tb3+的5D4→7E跃迁,ZAS∶ Tb3+在541 nm处发出明亮的绿色光;ZAS∶ Ce3+在381 nm处显示了蓝光发射,对应于Ce3的5d→4f轨道跃迁.ZAS∶RE3+(RE =Eu,Tb,Ce)的PL发射光谱存在着浓度猝灭现象,Eu3+、Tb3+和Ce3+的最佳单掺杂摩尔分数分别为20％、20％和3％.CIE色度图表明,ZAS∶ RE3+(RE=Eu,Tb,Ce)的色坐标分别位于红光、绿光和蓝光区域.实验结果表明,ZAS∶RE3+(RE=Eu,Tb,Ce)微晶玻璃是一种良好的可用于全色显示的白光LED材料.     

激发波长和Eu2+的掺杂量对Sr4 Al14 O25:Eu2+,Dy3+发光性能的影响

采用溶胶-凝胶法在低温、还原气氛下制备了长余辉发光材料Sr4 Al14O25:Eu2+,Dy3+.用X射线粉末晶衍射对其进行了物相鉴定,表明在1200℃已经得到纯相的Sr4Al14O25产物.研究了铕和锶的比值、激发光波长对所制备的Sr4 Al14O25:Eu2+,Dy3+发光性能的影响并对其影响机理进行了探讨.样品的发光性能测试结果表明:采用溶胶-凝胶法制备长余辉发光材料Sr4Al14O25:Eu2+,Dy3+,其灼烧温度比高温固相法灼烧温度低;激发光谱向长波方向延伸时,在488 nm处发射峰增强,在410 nm处发射峰减弱;在一定范围内发光强度随着Eu2+量的增加而增强,Eu2+的最佳掺杂量为0.007,Eu2+的掺杂量超过0.007时会发生浓度猝灭.     

Lu2SiO5:Ce透明薄膜改性及其发光性能

Lu2SiO5:Ce具有高密度、高光产额、快衰减等优点,是一种性能优异的新型X射线闪烁薄膜材料.本文采用溶胶-凝胶工艺和旋涂技术,以无机盐为原料、2-甲氧基乙醇为溶剂、聚乙二醇(PEG)为改性剂,在石英基片上成功制备出Lu2SiO5:Ce透明薄膜,较为详细地研究了PEG对该薄膜发光性能的影响.结果表明当采用浓度为12....     

CeO2:Eu3+粉末的溶胶-凝胶法制备及发光性能研究

采用溶胶-凝胶法制备了不同浓度Eu3 掺杂的CeO2发光粉,样品粉末在紫外光激发下发出明亮的橙红色光.利用X射线衍射(XRD)、热重-差热分析(TG-DTA)和光致发光光谱(PL)对样品的结晶过程和发光性质进行了表征.XRD分析表明在0.2at.%～10at.%的Eu3 掺杂范围内,用溶胶-凝胶法合成的样品在500℃就结晶成纯相的CeO2:Eu3 多晶粉末.由于Ce4 和Eu3 离子半径十分接近,因而Eu3 在CeO2中具有较高的固溶度.PL激发谱中出现在300～390 nm的宽带激发峰起源于基质CeO2的吸收,电子吸收能量后,发生O2--Ce4 的电荷迁移,再将能量传递给Eu3 .PL发射谱显示Eu3 含量为6at.%的样品发光强度最强,随后出现浓度猝灭.导致发光出现浓度猝灭的机制是电偶极-电四极相互作用.样品烧结温度的升高,促使晶粒长大和结晶完整性提高,从而显著提高了CeO2:Eu3 粉末的发光强度.     

以Eu-苯甲酸-1,10-菲咯啉为掺杂剂的SiO2,SiO2-B2O3和SiO2-B2O3-Na2O体系材料的结构及Eu3+的发光性质

用溶胶-凝胶法制备以Eu-苯甲酸-1,10-菲咯啉为掺杂剂的SiO2,SiO2-B2O3和SiO2-B2O3-Na2O为基质的发光材料.材料经1000℃退火处理后,结构十分稳定.通过激发光谱和发射光谱、红外光谱、TEM、XRD研究了基质结构对Eu3 发光性能的影响.结果显示:在589和614 nm处显示Eu3 的特征发射带,对应于Eu3 的5D0→7Fj(j=1,2)跃迁;与直接掺入EuCl3的玻璃材料相比,以Eu-苯甲酸-1,10-菲咯啉为掺杂剂的玻璃材料,虽然Eu的掺杂量较小,但Eu的发光强度较大.与以SiO2为基质的玻璃材料相比,以SiO2-B2O3为基质的玻璃材料Eu3 的发光减弱,其红外光谱显示形成Si-O-B键,说明该结构对Eu3 的发光有猝灭作用,以SiO2-B2O3-Na2O为基质的玻璃材料Eu3 的发光明显增强,其红外光谱显示不存在SiOB键的振动吸收,可能是Na取代B的位置,形成Si-O-Na键,此结构对Eu3 的发光有一定的增强作用.     

Bi3+掺杂对Sr2MgSi2O7:Eu2+荧光粉的结构及发光性能的影响

采用溶胶-凝胶法在还原气氛下制备了Sr2MgSi2O7∶Eu2+,xBi3+(x=0,0.02,0.04,0.06,0.08,0.1)荧光粉,并用XRD、TG-DTA及激发与发射谱仪对样品的结构及发光性能进行了表征.结果发现:单掺杂Bi3+的Sr2MgSi2O7样品的发射光谱所用的材料的激发光谱为一主峰为286 nm的宽带谱,这是由于激发态时Bi3+的3p1→1S0电子能级跃迁而造成的;单掺杂Eu2+的Sr2MgSi2O7样品的发射光谱所用的材料的激发光谱为一主峰为358 nm的宽带谱,这是典型的Eu2+的4f65d3→4f7跃迁而引起的.当Bi3+离子掺杂到Sr2MgSi2O7∶Eu2样品的摩尔分数为0.04时,样品的发射强度是未掺杂Bi3离子样品的1.9倍.     

CeO_2∶Eu~(3 )粉末的溶胶-凝胶法制备及发光性能研究

采用溶胶-凝胶法制备了不同浓度Eu3 掺杂的CeO2发光粉,样品粉末在紫外光激发下发出明亮的橙红色光。利用X射线衍射(XRD)、热重-差热分析(TG-DTA)和光致发光光谱(PL)对样品的结晶过程和发光性质进行了表征。XRD分析表明在0.2at.%～10at.%的Eu3 掺杂范围内,用溶胶-凝胶法合成的样品在500℃就结晶成纯相的CeO2∶Eu3 多晶粉末。由于Ce4 和Eu3 离子半径十分接近,因而Eu3 在CeO2中具有较高的固溶度。PL激发谱中出现在300～390nm的宽带激发峰起源于基质CeO2的吸收,电子吸收能量后,发生O2-—Ce4 的电荷迁移,再将能量传递给Eu3 。PL发射谱显示Eu3 含量为6at.%的样品发光强度最强,随后出现浓度猝灭。导致发光出现浓度猝灭的机制是电偶极-电四极相互作用。样品烧结温度的升高,促使晶粒长大和结晶完整性提高,从而显著提高了CeO2∶Eu3 粉末的发光强度。     

稀土Eu3+掺杂纳米TiO2-SiO2发光材料的制备和发光性质的研究

采用溶胶-凝胶法制备了稀土Eu3+掺杂于不同比例的纳米TiO2-SiO2复合体系,研究了基质中钛、硅摩尔配比对发光性能的影响.样品的FTIR谱图显示:纳米复合氧化物SiO2-TiO2之间发生了键合作用,形成了Ti-O-Si键;TEM显示样品的颗粒大小约为35 nm,是具有一定的单分散性的球形颗粒;XRD和SAED结果表明,样品退火至700℃后仍为单一的锐钛矿相,这说明微量硅的加入对二氧化钛的锐钛矿相有热稳定的作用.当微量的Si4+进入TiO2的晶格,取代部分Ti4+的位置时,形成了结构等电子陷阱.通过对样品的激发光谱、发射光谱分析,发现这种结构有利于将基质吸收的能量传递到发光中心,使Eu3+的465nm处7F0→5D2激发效率最高,成为最灵敏的激发线.     

激发波长和Eu2+的掺杂量对Sr4Al14O25 ∶ Eu2+ , Dy3+发光性能的影响

采用溶胶-凝胶法在低温、还原气氛下制备了长余辉发光材料Sr₄Al₁₄O₂₅ ∶ Eu²⁺,Dy³⁺。用X射线粉末晶衍射对其进行了物相鉴定,表明在1 200 ℃已经得到纯相的Sr₄Al₁₄O₂₅ 产物。研究了铕和锶的比值、激发光波长对所制备的Sr₄Al₁₄O₂₅ ∶ Eu²⁺, Dy³⁺发光性能的影响并对其影响机理进行了探讨。样品的发光性能测试结果表明:采用溶胶-凝胶法制备长余辉发光材料Sr₄Al₁₄O₂₅ ∶ Eu²⁺, Dy³⁺,其灼烧温度比高温固相法灼烧温度低;激发光谱向长波方向延伸时,在488 nm处发射峰增强,在410 nm处发射峰减弱;在一定范围内发光强度随着Eu²⁺量的增加而增强,Eu²⁺的最佳掺杂量为0.007, Eu²⁺的掺杂量超过0.007时会发生浓度猝灭。     

聚乙二醇对溶胶-凝胶SiO2增透膜激光损伤行为的影响

 采用溶胶-凝胶工艺制备了聚乙二醇（PEG）改性SiO₂单层增透膜,用输出波长1.06 μm,脉宽3 ns的调Q激光系统产生的强激光进行辐照实验。观察了添加PEG前后的膜层的微结构、表面形貌以及激光损伤行为的变化,讨论了PEG对薄膜激光损伤行为产生影响的机制。结果表明：添加的PEG可以修饰、导向溶胶簇团的生长和交联,并使之有序,由此制备的薄膜结构规整,微缺陷减少,这就提高了膜层的激光损伤阈值;在激光辐照过程中,膜料吸收激光能量,膜层温度升高,膜层的PEG分子受热逐步分解挥发,膜层产生损伤。     

"包络法"在Ba(ZrTi)O3铁电薄膜中的应用

采用溶胶一凝胶法在石英衬底上制备Ba(ZrTi)O3铁电薄膜,U-3010紫外光谱仪测量BZT薄膜的透射光谱,光谱表明制备的BZT薄膜样品厚度均匀,利用“包络法”计算出薄膜的厚度约为301.3nm,并得到薄膜的复折射率随入射光频率的变化曲线,进一步拟和出BZT薄膜的透射谱。研究表明在紫外光区到近红外光区“包络法”计算精度高。     

Ordered luminescent nanohybrid thin films of Eu(BA)3Phen nanoparticle in polystyrene matrix from diblock copolymer self-assembly

A simple route for fabricating highly ordered luminescent thin films based on hybrid material of diblock copolymer and europium complex, assisted with self-organization of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymer upon solvent annealing, is presented. PS-b-PEO self-organized into hexagonal patterns and europium complex of Eu(BA)₃Phen was selectively embedded in PS blocks after solvent annealing in benzene or benzene/water vapor. During benzene annealing, the orientation of the PEO cylindrical domains strongly depended on the Eu(BA)₃Phen concentration. In contrast, when the hybrid thin films were annealed in mixture of benzene and water vapor, high degree of orientation of the PEO cylindrical domains is more easily obtained, which is independent of Eu(BA)₃Phen concentration. Furthermore, preferential interaction of PEO domains with water induces a generation of nanopores in the hybrid thin film. Atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to characterize the long-range lateral order and phase composition of the hybrid thin films. The ordered nanohybrid thin films kept the fluorescence property of Eu(BA)₃Phen and showed a strong red emission under the 254 nm light's irradiation. The fluorescence property was confirmed by photoluminescence (PL) spectra.     

Effect of pressure on cubic (C-type) Eu2O3 studied via Eu3+ luminescence

Abstract

Luminescence spectra from Eu³⁺ ion in C-type Eu₂O₃ under high pressures have been obtained. The spectral shifts can be used to study the effect of pressure on the spin-orbit and the Coulomb interactions of the 4f electrons, which are correlated with expansion of the 4f-electron wave functions. This expansion with the application of pressure results in both the variation of the electronegativity and radius of the Eu³⁺ ion and, ultimately, the phase transformation from C-to B-type Eu₂O₃. Therefore, core 4f-electrons can thus be thought of as quasivalence electrons.     

Influence of Eu doping content on photoluminescence of Gd2O3:Eu phosphors prepared by liquid-phase reaction method

Europium-doped cubic Gd₂O₃:Eu³⁺ nanoparticles containing various activator content in the range of 5-15 wt% were synthesized by a liquid-phase reaction method to investigate the influence of Eu³⁺ loading on the optical properties of phosphors by using XRD, TEM, BET, spectrometer and fluorometer. The size of Gd₂O₃:Eu³⁺ powders was in the range 21-41 nm. The phosphors showed an initial increase in luminescence and then a subsequent decrease with further doping (above 10 wt%). The decay time was reduced with increasing Eu loading; however, it decreased significantly above the 10% Eu doping. From spectroscopic studies, the Eu³⁺ doping ion distribution was uniform and homogeneous up to the 10 wt% loading because no concentration quenching effect was observed. However, further Eu³⁺ doping above 10 wt% reduced the luminescence due to the concentration quenching effect, as deduced from the shortening of the decay time.     

Optical transition properties of Eu in Eu(DBM)3phen mono-dispersed microspheres for microcavity laser application

Mono-dispersed microspheres of ternary complex Eu(DBM)₃phen (DBM=dibenzoylmethide; phen=1,10-phenanthroline) were prepared through a facile process. The obtained sample was characterized by means of X-ray powder diffraction (XRD) and scanning electron microscope (SEM). And the luminescence properties of the Eu(DBM)₃phen were investigated by the fluorescence spectra and the fluorescence decay. According to Judd-Ofelt theory, the optical transition intensity parameters Ω_λ (λ=2, 4 and 6) were obtained to be 20.99×10⁻²⁰, 0.98×10⁻²⁰ and 1.79×10⁻²⁰ cm², respectively. The radiative transition properties of ⁵D₀ level, including transition rates, branch ratios and radiative transition lifetime were calculated. As a potential material for microsphere lasers, the optical gain performance for ⁵D₀→⁷F₂ transition was also evaluated.     

Sol-gel法制备CaSnO_3∶Eu~(3+)发光粉过程中添加PEG的作用

采用sol-gel法制备CaSnO3:Eu3+荧光粉。研究了在制备过程中添加表面活性剂聚乙二醇(PEG10000)对CaSnO3:Eu3+结构、粒度、形貌及发光性能的影响。通过X射线衍射(XRD)、激光粒度仪,扫描电镜(SEM)及荧光分光光度计对样品进行了表征。结果表明:在制备过程中添加PEG没有改变样品的结构,很好地改善样品粒度以及形貌,荧光粉的相对发光强度也稍有增强。     

Luminescent properties of R2(MoO4)3:Eu (R=La, Y, Gd) phosphors prepared by sol-gel process

A series of red phosphors R_0.8Eu_1.2(MoO₄)₃ (R=La, Y, and Gd) have been synthesized by sol-gel method. The crystallization processes of the phosphor precursors were characterized by X-ray diffraction (XRD) and thermogravimetry-differential thermal analysis (TG-DTA), and the properties of these resulting phosphors have also been characterized by photoluminescence (PL) spectra and reflectance spectra. Field emission scanning electron microscopy (FE-SEM) was also used to characterize the shape and the size of the samples. The results of TG-DTA and XRD indicated that all of the R_0.8Eu_1.2(MoO₄)₃ (R=La, Y, and Gd) phosphors crystallized completely at 650 °C. Y_0.8Eu_1.2(MoO₄)₃ and Gd_0.8Eu_1.2(MoO₄)₃ have two structures, monoclinic and orthorhombic, while La_0.8Eu_1.2(MoO₄)₃ only adopts monoclinic structure. The luminescent properties of phosphors R_0.8Eu_1.2(MoO₄)₃ (R=La, Y, and Gd) are dependent on their structures to some extent. The orthorhombic Y_0.8Eu_1.2(MoO₄)₃ and Gd_0.8Eu_1.2(MoO₄)₃ phosphors show very similar luminescent properties, which differ from those of phosphors with monoclinic structure. For all of R_0.8Eu_1.2(MoO₄)₃ (R=La, Y, and Gd) phosphors, intense red emission is obtained by exciting at ∼394 and ∼465 nm which are owing to the sharp ⁷F₀→⁵L₆ and ⁷F₀→⁵D₂ lines of Eu³⁺. Two strongest lines at 394 and 465 nm in excitation spectra of these phosphors match well with the two popular emissions from near-UV and blue GaN-based LEDs, so they could be used as red components for white light-emitting diodes.     

Effect of Eu contents on the structure and properties of BaLa2ZnO5:Eu phosphors

A series of Eu³⁺ doped BaLa₂ZnO₅ was prepared by a Pechini-type sol-gel method. The effect of Eu³⁺ concentration on the structure and the luminescent properties of the samples BaLa_2−xEu_xZnO₅ were investigated by powder X-ray diffraction (XRD) and photoluminescence (PL) spectra. The sample adopts the tetragonal or orthorhombic structure as the Eu³⁺ concentration reaches below 1.2 or over 1.6, respectively. The sample is a mixture of tetragonal and orthorhombic phases as the contents of dopants lie between 1.2 and 1.6. The phosphor offers the strongest red light as content of Eu³⁺ is 0.4. In addition, the crystallization processes of the complex precursors were examined by simultaneous thermogravimetry and differential thermal analysis (TG-DTA), and also the optimal heating temperature was investigated.     

(Sr,Ca)4Si3O8Cl4基质中Eu2+的发光特性研究

采用高温固相法合成Sr4-xCaxSi3O8Cl4：Eu^2＋荧光材料,利用Van Uitert公式讨论Sr4-xCaxSi3O8Cl4：Eu^2＋中yEu^2＋的晶格环境和发光特性,确定晶体中有蓝色和黄绿色两种发光中心,并讨论了它们与光谱结构的对应关系。当0〈x〈0．5,Ca^2＋固溶入Sr4Si3O8Cl4基质晶格,Eu^2＋占据八配位Si^2＋格位,晶体主要产生蓝色中心的蓝绿色发射;当0．5〈x〈2,较大的Ca^2＋掺杂使晶胞参数变小,品格中的杂质束缚激子态的束缚增强,Eu^2＋处于杂质束缚激子中心所形成的激发态能量进一步降低,发射位于长波段方向并具有较大的Stokes位移,Sr4-xCaxSi3O8Cl4：yEu^2＋主要产生黄绿色中心的黄绿色发射光。