磷酸盐玻璃中Tb^3＋离子的敏化发光与能量传递

研究了磷酸盐玻璃中Ｔｂ＾＋离子的敏化发光。结果表明；磷酸盐玻璃中Ｄｙ＾３＋，Ｃｅ＾３＋和Ｔｂ＾３＋产生敏化发光。确立了双掺Ｔｂ＾３＋和Ｄｙ＾３＋玻璃中Ｄｙ＾３＋－Ｔｂ＾３＋敏发化光的声子支助共振能量转移模型，双掺Ｔｂ＾３＋和Ｃｅ＾３＋玻璃中Ｃｅ＾３＋的激光发能通过无辐射能量共振转移每化发光，计算出Ｃｅ＾３＝－Ｔｂ＾３＋的有量传递效率，为确定最佳稀土离子掺加量提供了依据。     

北川体育场高空悬挑看台梁板模板设计与施工

通过四川北川县体育场高空悬挑看台梁板支模工程的实践,验证了高大空间复杂外形工程条件下扣件式钢管脚手架的适用性.明确了脚手架结构验算的部位,表明了轴心受压对立杆稳定性的影响,指出了施工重点部位.扣件式脚手架用于复杂外形结构有易于操作、经济性好和适用性强的优点.     

Synthesis by oxidative polymerization with FeCl3 of a fully aromatic twisted poly(3,6-carbazole) with a blue-violet luminescence

Oxidative polymerization of 1,4,5,8,9 pentamethylcarbazole with FeCl₃ in chloroform solution, yields a new electroactive well-defined poly(3,6-carbazole) with a twisted structure due to steric hindrance of the adjacent monomer units. This non-coplanar structure allows, for the first time, to a carbazole compound to be converted in high polymer by the dehydrocoupling route using FeCl₃ as the oxidizing agent. Soluble materials with molecular weights M_w around 10⁴, high glass transition and thermal stability in air, were obtained. Electrochemical studies of polymer films exhibited one irreversible oxidation process at high potential consistent with a non-conjugation between the carbazole moities. Moreover, deviation from the coplanarity of consecutive rings of poly(1,4,5,8,9-pentamethyl-3,6-carbazolylene) permits these materials to emit a bright pure blue-violet light with no excimer formation, which can be interestingly used for the development efficient light-emitting diodes.     

SrAl_2O_4∶Eu~(2+),Dy~(3+)荧光粉的合成及表征

为了提高SrAl_2O_4∶Eu~(2+),Dy~(3+)荧光材料的发光强度和余辉时间,采用高温固相法合成了SrAl_2O_4∶Eu~(2+),Dy~(3+)荧光粉.利用X射线衍射仪、扫描电子显微镜和荧光光谱仪对产物的化学成份、结构、微观形貌和发光特性进行了分析.结果表明,SrAl_2O_4∶Eu~(2+),Dy~(3+)荧光粉的最佳煅烧温度为1 500℃,最佳煅烧时间为3 h.当Eu_2O_3的质量分数为2%时,Sr Al2O4∶Eu2+荧光粉的发光强度最大;当Eu_2O_3的质量分数为1.5%时,SrAl_2O_4∶Eu~(2+)荧光粉的余辉性能最好;当Eu_2O_3的质量分数为2%、Dy_2O_3的质量分数为4%时,SrAl_2O_4∶Eu~(2+),Dy~(3+)荧光粉的发光强度和余辉性能最好.     

下一代无源光网络的演进路线与研究进展

无源光网络是目前实现宽带接入的主流技术,正处于快速演进阶段。在比较下一代无源光网络备选技术的基础上,重点介绍多波长堆叠无源光网络的工作原理和关键实现技术,并综述了这种无源光网络的实验演示系统现状和低成本光网络单元研究进展。     

Solution growth of millimeter-scale Na2SiF6 single crystals for Mn4+-doping as red phosphor

The cation exchange method has been demonstrated to be efficient in doping Mn⁴⁺ ions into various fluorides to synthesize the red-emitting LED phosphors. This paper, however, reports the challenge in using this method to dope Mn⁴⁺ into the Na₂SiF₆ single crystals, to prepare the fluoride phosphor in single-crystal form, a state-of-the-art study in the white LED lighting field. The millimeter-sized Na₂SiF₆ single crystals with a uniform columnar morphology (2–3 mm in length) were successfully grown in solution by a slow cooling process after optimizing the precursors. Then, the crystals were soaked in the HF solution dissolved with K₂MnF₆ to implement Mn⁴⁺-doping via the cation exchange process. Evaluation of the Mn⁴⁺-doping behavior reveals that the Mn⁴⁺ ↔ Si⁴⁺ cation exchange is less efficient in the case of single crystal host compared with the polycrystalline powdery ones and by-reactions also occur which generates new phases. The Na₂SiF₆ single crystals doped with Mn⁴⁺ exhibit a series of discrete sharp peaks with intense zero phonon line emission at 617 nm under 450 nm blue irradiation. This study may trigger the exploration of new single crystal fluoride phosphor.     

Competitive Cr3+ occupation in persistent phosphors toward tunable traps distribution for dynamic anti-counterfeiting

Red/near infrared (NIR) long persistent phosphors have received extensive attentions in biomedical, food inspection, iris recognition, biological imaging, etc. Herein, a new phosphor, Li₂ZnGe₃O₈:Cr³⁺, is reported with deep red persistent luminescence peaking at 708 nm. By adjusting the Cr³⁺ doping concentration, the competitive site occupation at [ZnO6] and [GeO6] polyhedral enables different traps behaviors including trap types, trap concentration and trap depth, which in turn leads to different afterglow duration time from 2 to 20 h. The persistent luminescence mechanisms originated from different trap models have been discussed, and it is found that they can cooperate or inhibit each other, enabling different luminescence depending on time. The dynamic anti-counterfeiting applications have been demonstrated, which provides a new way to rationally designing for multi-functional luminescent materials.     

Low temperature thermoluminescence properties of Eu and R doped CaAl2O4

The thermoluminescence (TL) of calcium aluminate persistent luminescence materials doped with Eu²⁺ and co-doped with R³⁺ ions were studied between 20 and 325 K. The basic material, CaAl₂O₄:Eu²⁺, showed three TL bands between 150 and 300 K in the glow curve. Changing the R³⁺ co-dopant to the adjacent element in the rare earth series affects significantly the thermoluminescence intensity and even the position of the glow curve maximum. The physical effect seemed to be removing the traps since the La³⁺, Y³⁺, and Lu³⁺ ions suppressed the thermoluminescence. The Pr³⁺, Ho³⁺, and Dy³⁺ co-doping enhanced mainly the low temperature traps and these materials have an intense but relatively short persistent luminescence at room temperature. The Nd³⁺ and Tm³⁺ ions enhanced the TL bands close to room temperature and are thus the most suitable co-dopants to induce intense and long persistent luminescence. The quenching of the thermoluminescence by Sm³⁺ was concluded to be due to the presence of Sm²⁺ that removes totally the traps.     

Synthesis and luminescent properties of Eu~(3+)-doped Na_(24)As_2W_(22)O_(83)

The Eu3+-doped Na24As2W22O83 phosphor has been prepared by solid state reaction from Na3AsO412H2O, Na2WO4 2H2O and WO3, and characterized by elemental analysis, infrared spectroscopy and powder X-ray diffractometry. According to the measurements with X-ray diffraction, this material belongs to orthorhombic system with its lattice constants: a = 1.4750 nm, b = 1.1944 nm, c = 1.1062 nm, it is consistent with space group D24-P212121 (No.19). The emission and excitation spectra were measured. The luminescent properties of Eu3+-doped Na24As2W22O83 and mechanism of energy transfer were discussed.     

可调谐钛宝石双波长激光在β－BaB2O4晶体中和频

本文用矩阵光学推导出了相位共轭腔的热稳条件。