Sm3+杂CaO-SiO2-B2O3发光玻璃的制备、表征及性质

用高温固相法合制备了以CaO-SiO2-B2O3为基质,Sm3+为激活离子的发光玻璃.对Sm3+的淬灭浓度、基质中的硼硅比例、其他稀土离子的敏化作用以及基质组成等因素对玻璃发光特性的影响进行了探讨,并用红外和X-衍射分析对样品的结构进行了表征.结果表明:当Sm3+掺杂的物质的量分数为1.2%,激发波长λ=404 nm时,玻璃体60CaO-20SiO2-20B2O3:1.2Sm3+的发光强度为4838 A.U.(λ=606 nm);这种发光玻璃具有将紫外及近紫外光转换为橙红色光的特点.少量的Eu3+的掺入,对玻璃体的发光起敏化作用;玻璃体中的组分CaO可被ZnO替代.     

纳米SrAl2O4:Eu2+,Dy3+长余辉发光材料的制备与性能

采用水热-均匀共沉淀法制备了纳米SrAl2O4:Eu2+,Dy3+长余辉发光材料.通过XRD、TEM、荧光光谱、热释光谱对其结构和性能进行分析.XRD结果表明所制备的SrAl2O4:Eu2+Dy3+纳米发光材料为单相,属单斜晶系.TEM测试表明纳米SrAl2O4:Eu2+,Dy3+发光材料为规则的球状粒子,粒径为50～80 nm,且分散性良好.激发和发射光谱测试表明,样品的激发光谱是峰值在356 nm 的连续宽带谱,发射光谱是峰值位于512 nm的宽带谱,与SrAl2O4:Eu2+,Dy3+粗晶材料相比,激发和发射光谱都出现了"蓝移"现象.样品的热释光峰值位于358 K,适合于产生长余辉.     

CaO-SiO2-B2O3:Sm2O3玻璃的合成及Sm3+发光性质研究

用常规的高温合成法合成了CaO-SiO2-B2O3Sm2O3玻璃, 探讨了玻璃的最佳合成温度、玻璃的吸收光谱, 并研究了其发光性质. 在CaO-SiO2-B2O3Sm2O3玻璃体系中观察到了Sm3+的发射光谱. 样品的发射光谱有3个主要荧光发射峰, 峰值波长分别为568, 605, 650 nm, 其中最强峰为605 nm,可见发射起源于Sm3+离子4f电子的f-f跃迁. 其中568 nm对应于4G5/2→6H5/2跃迁、 605 nm对应于4G5/2→6H7/2跃迁、 650 nm对应于4G5/2→6H9/2跃迁, 光谱性质表明这种玻璃体系能够把太阳光中的紫外光转换成红光, 从而增强红光的发射强度. 可以利用这些玻璃的发光性质来制备农用转光玻璃.     

Sr2SiO4:Eu3+发光材料的制备及其光谱特性

采用溶胶-凝胶法制备了Sr2SiO4:Eu3+发光材料. 测量了Sr2SiO4:Eu3+材料的激发与发射光谱, 发射光谱主峰位于618 nm处;监测618 nm发射峰时, 所得激发光谱主峰分别为320、397、464 和518 nm. 研究了Sr2SiO4:Eu3+材料在618 nm的主发射峰强度随Eu3+浓度的变化情况. 结果显示, 随Eu3+浓度的增大, 发射峰强度先增大; 当Eu3+浓度为7%时(x), 峰值强度最大; 而后随Eu3+浓度的增大, 峰值强度减小. 在Eu3+浓度为7%的情况下, 研究了电荷补偿剂Li+的掺杂浓度(x(Li+))对Sr2SiO4:Eu3+材料发射光谱强度的影响. 结果显示, 随x(Li+)的增大, 材料发射光谱强度先增大后减小, 当x(Li+)为8%时, 峰值强度最大.     

Eu3+掺杂SiO2-Al2O3-B2O3玻璃制备及光谱性能研究

高温溶制了Eu^3＋掺杂SiO2-Al2O3-B2O3-MxOy（M=Li^＋,Na^＋,K^＋,Mg^2＋,Ca^2＋,Sr^2＋,RE^3＋）硼硅酸盐玻璃,测试了玻璃样品的发射光谱、激发光谱和透射光谱,研究了不同碱金属离子、碱土金属离子对该系统荧光性能的影响。利用发射光谱计算了Ω2,Ω4以及^5D0到^7F2,^7F4的自发辐射几率和振子强度f（^5D0→^7F2）,f（^5D0→^7F4）。结果表明,材料的发射能级为^5D0→^7F1（590nm）,^5D0→^7F2（617nm）,^5D0→^7F4（698nm）,而且材料的结构对称性越差,跃迁戒律打破地越彻底,荧光发射越强。     

Tb掺杂SiO2-B2O3-NaF玻璃的制备及发光性质

使用正硅酸乙酯、硼酸和氟化钠为前驱体,0.10 mol•L-1TbCl3溶液为掺杂剂,通过溶胶-凝胶方法制备了Tb3＋掺杂的SiO2-B2O3-NaF玻璃,研究了Tb3＋在SiO2-B2O3-NaF体系中的发光性质,结果显示发光体能产生强的绿色发光(544 nm),归属于Tb3＋的5D4—7F5电子跃迁.Tb3＋含量不同时,除发光强度不同外,其发射光谱基本相同,并且在低掺杂Tb3＋样品和低退火温度样品中检测到了来自5D3跃迁产生的峰,其跃迁随Tb3＋掺杂浓度的增加和退火温度的升高而发生猝灭,这种现象归因于5D3－5D47F6—7F0和/或5D3—7F07F6—5D4跃迁中发生了交叉弛豫现象.Tb3＋在SiO2-B2O3-NaF玻璃中的激发光谱由一个宽峰和一系列窄峰组成,宽峰最大波长位于230 nm,对应于Tb3＋的4f 8—4f 75d 1跃迁,一系列窄峰位于300～380 nm处,归属于4f 8跃迁,所有发光材料的XRD和TEM测试显示材料是非晶态的.     

SiO2／LaF3：Eu3＋核壳结构发光粒子的制备与表征

采用简单的液相法合成了SiO2/LaF3:Eu3 核壳结构发光粒子,并对其结构及发光性能进行了表征.XRD分析表明包覆层LaF3:Eu3 为立方晶相结构,红外光谱表明SiO2颗粒表面有柠檬酸的修饰,电镜照片表明合成了球形的核-壳结构的复合粒子,包覆层厚度为10～20 nm,光谱测试表明核-壳复合粒子与纯的LaF3:Eu3 具有相同的发光性能,均以589 nm附近的5D0-7F1磁偶极跃迁为最强发射峰,说明Eu3 在LaF3基质中占据的格位相同.     

溶胶-凝胶法制备掺Eu3+的SiO2玻璃的结构及发光性

利用溶胶-凝胶技术制备了掺不同量Eu3+和不同退火温度下的SiO2凝胶和玻璃,通过在不同退火温度下样品的激发光谱、发射光谱、红外光谱和差热-热重曲线,研究了掺Eu3+的SiO2玻璃材料的结构和发光性能。结果显示当Eu3+的掺杂量大于1.86%（质量分数）,Eu3+的发光强度趋于稳定,当样品的退火温度大于300℃时,SiO2凝胶玻璃中吸附的水已基本除净,此时显示出Eu3+的特征发射光谱,谱带位置分别是614,596,588,577nm,分别归属于5D0-7F2,5D0-7F1,5D0-7F0跃迁,对应的激发光谱显示6个峰,位置分别是318,362,380,393,412,462nm,说明300～500℃是凝胶向玻璃转变的关键温度,而水对Eu3+的发光有强烈的淬灭作用。     

溶胶—凝胶法制备掺Eu^3＋的SiO2玻璃的结构及发光性能

利用溶胶－凝胶技术制备了掺不同量Eu^3 和不同退火温度下的SiO2凝胶和玻璃,通过在不同退火温度下样品的激光发谱,发射光谱,红外光谱和差热－热重曲线,研究了掺Eu3 的SiO2玻璃材料的结构和发光性能,结果显示,当Eu3 的掺杂量大于1．86％（质量分数）,Eu^3 的发光强度趋于稳定,当样品的退火温度大于300度时,SiO2凝胶玻璃中吸附的水已基本除净,此时显示出Eu^3 的特征发射光谱,谱带位置分别是614,596,577nm,分别归属于^5Do-7F2,5D0-7F1,^5D0-^7F0跃迁,对应的激光发光谱显示6个峰,位置分别是318,362,380,393,412,462nm,说明300－500度是凝胶向玻璃转变的关键温度,而水对Eu^3 的发光有强烈的淬灭作用。     

Eu2+/Mn2+激活的M3MgSi2O8-M2SiO4(M=Ba,Ca)荧光粉的发光特性

采用高温固相法制备了Eu2+/Mn2+单激活和共激活的M3MgSi2O8-M2SiO4(M=Ba,Ca)两相荧光粉.通过X射线衍射(XRD)和荧光光谱(PL)对样品材料的晶体结构和光谱性能进行了表征.XRD测试结果表明所合成的样品具有M3MgSi2O8和M2SiO4两种晶相结构.PL测试显示,Eu2+在Ba3MgSi2O8-Ba2SiO4体系中发射442和502nm两个波带的光;而Eu2+在Ca2+部分取代Ba2+的BaCa2MgSi2O8-Ba1.31Ca0.69SiO4体系中发射420～520nm的连续波带,并且激发光谱向长波扩展,更加适用于被InGaN芯片(395 nm)激发.通过改变Mn2+的掺杂量可制得颜色可调的BaCa2MgSi2O8-Ba1.31Ca0.69SiO4:Eu2+,Mn2+白光荧光粉.     

Multilayer SiO2-B2O3-Na2 O Films on Si for Optical Applications

The fabrication of glass by the sol-gel technique has attracted considerable attention in microelectronics, optics and other fields. For applications in integrated optics on silicon substrates, sol-gel offers the possibility of a great variety of compositions and structures. For example, the porosity may allow the insertion of a dopant species, such as nano-crystals for optical non-linearity, into the host glass. Here we have investigated SiO2-B2O3-Na2O compositions, to obtain low process temperatures, and to prepare SiO2 guiding layers with a porosity control using the Vycor glass method.Films of several micron thickness were prepared in many compositions of the SiO2-B2O3-Na2O system. The process included a two-step method to introduce the water while inhibiting crystal formation, a repetitive spin-coating technique in a humidity-controlled chamber, and rapid-thermal-annealing. The results show good quality in terms of homogeneity, absence of cracks, and versatility in the studied compositions. However, films prepared using rapid thermal annealing show a high residual carbon concentration. This causes strong optical absorption, and inhibits the phase separation and leaching associated with the Vycor technique. Reduction of carbon content has been investigated through adaptation of the heat treatment.     

Synthesis and characterization of SiO2/Gd2O3:Eu core-shell luminescent materials

Europium-doped Gd2O3 with an average size of approximately 15 nm was coated on the surface of preformed silica nanospheres by the wet chemical method. SEM and TEM photographs showed that SiO2/Gd2O3:Eu core-shell submicrospheres are obtained. XRD patterns indicated that the Gd2O3:Eu shell is crystalline after heat treatment. FTIR and XPS spectra showed that the Gd2O3:Eu shell is linked to the silica surface by forming a Si-O-Gd bond. Photoluminescence studies showed that the luminescent properties are still retained after coating on an inert silica core; additionally, we noted that the emitting peaks are broadened, which results from size effects and interface effects of nanocrystal.     

Synthesis and properties of europium-based phosphors on the nanometer scale: Eu2O3, Gd2O3:Eu, and Y2O3:Eu

Nanocrystals of oxides containing europium as the main constituent or as a doping element in RE2O3 ( RE=Y, Gd) have been prepared by direct oxide precipitation in high-boiling polyalcohol solutions and characterized by high-resolution TEM, absorption spectroscopy, and luminescence spectroscopy. The samples obtained consisted of concentrated and colloidally stable suspensions of luminescent oxide nanoparticles with an average grain diameter in the range 2-5 nm. The nanoparticles were found to be highly crystalline despite their ultrasmall size and the low temperature of 180 degrees C applied during the synthesis. Upon UV excitation, the red luminescence relative to the 5D0-->7Fn transition within the cubic form of RE2O3 exhibits some important differences from that usually found in bulk materials.     

纳米(Y0.95Eu0.05)2O3及其SiO2气凝胶介孔组装体的制备与光致发光

采用尿素溶胶法合成(Y0.95Eu0.05)2O3纳米粉,用超临界干燥技术制备了n-(Y0.95Eu0.05)2O3/SiO2气凝胶介孔组装体。结果表明,当Y3+∶　Eu3+=20∶　1,均相反应时间为4 h,且经680℃、 4 h灼烧热处理后得到的n-(Y0.95Eu0.05)2O3中, 光致发光强度最大（发光峰位于612 nm),以Si与 2Y摩尔比为1∶　7的n-(Y0.95Eu0.05)2O3/SiO2气凝胶介孔组装体,经同样条件热处理后,光致发光强度达不到n-(Y0.95Eu0.05)2O3的红光发射强度,而且峰位出现红移（发光峰在616 nm）。对产生上述发光强度减弱和峰位红移现象进行讨论。     

Phase equilibria in the BaO-Bi2O3-B2O3 system

Phase equilibria in the BaO-Bi₂O₃-B₂O₃ system have been investigated by X-ray powder diffraction analysis and DTA. Quasi-binary sections have been determined, and an isothermal section of the system in the subsolidus region has been constructed. The BaO-Bi₂O₃-B₂O₃ ternary system has been divided into 22 triangles of coexisting phases. It has been found that four bismuth barium borates exist, namely, Ba₃BiB₃O₉, BaBi₂B₄O₁₀, BaBiB₁₁O₁₉, and BaBiBO₄. Ba₃BiB₃O₉ undergoes a phase transition at 850°C and exists up to 885°C, where it decomposes in the solid state. BaBiB₁₁O₁₉ and BaBi₂B₄O₁₀ melt congruently at 807 and 730°C, respectively. BaBiBO₄ melts incongruently at 780°C. X-ray powder diffraction data for the low-temperature polymorph of Ba₃BiB₃O₉ are presented.     

Site selection spectroscopy of SiO2:Eu3+ gels

Silica gels doped with Eu³⁺ ions were studied at temperatures between 10 K and 300 K by site selection spectroscopy in samples heated up to 200°C. The ⁵D₀ ⁷F₀ transition shows internal structures due to the different environments of the europium ions. Lifetimes, energy levels and homogeneous linewidths are site dependent. In the wet gel the Eu³⁺ ions prefer a liquid-like environment and only when the liquid is removed by heat treatment, the ion is linked more strongly to the silica network.     

Thermoluminescent Properties of Tridymite SiO2 : Al3+, Eu3+

SiO₂ crystals have been used in electroluminescence devices and thermoluminescence (TL) dosimeters. However, their emission mechanisms have not yet been clearly explained. Recently, it has become possible to obtain amorphous, highly pure, SiO₂ prepared by the sol-gel method. The emission mechanism of TL was investigated using Al³⁺ and/or Eu³⁺-doped SiO₂ crystalline samples prepared by heat-treating under much lower temperature than the melting point of SiO₂. The TL spectrum of Eu³⁺-doped sample had main peaks due to the electron transitions from ⁵D₂ to ⁷F₅ (ca. 570 nm, yellow peak) and from ⁵D₀ to ⁷F₂ (ca. 610 nm, red peak). The yellow peak intensity has a maximum value in the SiO₂ doped with near 1 mmol% of Eu₂O₃, while the red peak intensity was almost constant. These facts suggest that bright yellow emission of SiO₂TL phosphor is synthesized by the diffusion of Eu³⁺ ion in SiO₂ matrix prepared by sol-gel method.