稀土Er3+离子掺杂的全无机CsPbCl3钙钛矿纳米晶的合成及发光性能

CsPbCl₃全无机钙钛矿纳米晶(PNC)的应用受到其弱发光、极低的光致发光量子产率(PLQY)以及长期暴露于氧气和湿气环境中稳定性差等的限制。为了解决这一问题,使用稀土金属元素铒的三价阳离子(Er³⁺)作为B位掺杂元素,制备出了明亮蓝紫光发射的Er³⁺∶CsPbCl₃钙钛矿纳米晶发光材料。掺杂后的纳米晶具有最佳的形貌和发光性能:PLQY为16.7%、平均粒径约为7.98nm、荧光发射峰蓝移至400nm、半峰全宽仅为10.0nm。同时该纳米晶的环境稳定性也显著提升,在测试环境(温度60℃、湿度60%RH)下存放10天后,其发光强度仍能保持初始荧光发射强度的60%以上。此工作较大程度上改善了CsPbCl₃钙钛矿纳米晶存在的问题,对于其实际应用存在重大意义。     

Sb3+/Bi3+掺杂对Cs3DyCl6钙钛矿光学性能的影响

A₂B′BCl₆双钙钛矿因其极强的空气稳定性、出色的光学性能而被应用于发光材料。以Cs⁺作为A⁺、Dy³⁺替代Pb²⁺、Cl^-作为卤素合成新的镝基钙钛矿纳米晶体Cs₃DyCl₆,以Sb³⁺/Bi³⁺作为激发剂掺杂,成功制备了非铅钙钛矿材料,研究了Sb³⁺/Bi³⁺掺杂对钙钛矿发光特性的影响。结果表明：Cs₃DyCl₆是一种具有高效激发和宽带发射特性的基质,在不添加任何激发剂的情况下就能够发出蓝绿光。在Sb³⁺掺杂下,材料的发光向黄光方向移动,随着Sb³⁺掺杂浓度的继续提高,发光强度开始下降,最佳掺杂比例为5%;Bi³⁺掺杂时的Cs₃DyCl₆光学性能与S...     

Sm3+离子掺杂对BaGa2O4∶Cr3+近红外长余辉发光的增强研究

利用高温固相法制备了BaGa₂O₄∶Cr³⁺,Sm³⁺(BGO∶Cr,Sm)近红外长余辉发光(PersL)材料，考察了Sm³⁺掺杂浓度和煅烧温度对BGO∶Cr,Sm晶体结构和发光性能的影响，初步探讨了近红外余辉发光机理。结果表明：当长余辉发光材料组成为BGO∶Cr_0.06,Sm_0.004且煅烧温度为1100℃时，可以获得高纯度的BGO∶Cr,Sm长余辉发光材料，其发射波长为734 nm。Cr³⁺与Sm³⁺共掺杂为应用于生物成像的BGO提供了优化策略，同时为开发长余辉发光材料提供了良好范例。     

新型白光LED荧光粉Y2O3:Ti 3+的光谱性能

采用共沉淀法,在不同的烧结气氛下制备了Y₂O₃:Ti ³⁺粉体,测量了它们的激发、发射光谱以及XRD光谱,观测了形貌。在紫外光激发下,微晶Y₂O₃:Ti ³⁺在439nm附近有较强的发射带,而纳米Y₂O₃:Ti ³⁺在400~500nm范围内出现了强的发射带。随纳米粉体的晶粒尺寸减小,它的发光明显增强,覆盖了整个可见光区。结果表明Y₂O₃:Ti ³⁺纳米粉体有望成为新一代白光LED或汞灯的光转换荧光粉。     

Y3MgAl3SiO12:Dy 3+,Eu 3+荧光粉的能量传递与暖白光实现

采用高温固相法合成了Dy ³⁺、Eu ³⁺共掺杂Y₃MgAl₃SiO₁₂石榴石型荧光粉。采用XRD、荧光光谱仪等仪器对样品的结构以及光谱特性进行表征,探究了Dy ³⁺/Eu ³⁺在Y₃MgAl₃SiO₁₂基质结构中的光谱特征以及离子间的能量传递机制。在367 nm近紫外光激发下,Y₃MgAl₃SiO₁₂:Dy ³⁺,Eu ³⁺的发射光谱包含Dy ³⁺的6F9/2到6H15/2和6H13/2的电子跃迁特征发射(487 nm蓝光和592 nm黄光)和Eu ³⁺的5D0 7F2 and 5D0 7F4特征发射峰(616 nm和710 nm红光)。在400~500 nm范围内Dy ³⁺发射谱与Eu ³⁺激发谱重叠,表明Dy ³⁺与Eu ³⁺之间存在着能量传递,能量传递的机理为电四极-电四极相互作用。该荧光粉通过调整Dy ³⁺和Eu ³⁺的掺杂浓度比封装近紫外LED芯片,可以实现单基质暖白光LED照明。     

Sm3+离子激活Y2MgTiO6橙红色荧光粉的制备及发光性质研究

采用溶胶-凝胶法合成了一系列橙红色发光的Y_2-2xMgTiO₆∶2xSm³⁺(YMT∶2xSm³⁺,0≤x≤0.11)荧光粉。通过粉末X射线衍射仪(XRD)、扫描电子显微镜(SEM)、光致发光激发和发射光谱对样品进行了表征分析。结果表明，所制备的YMT∶Sm³⁺样品为纯相，无任何杂质；荧光粉颗粒尺寸为2～3μm,分散性较好且无明显团聚。在407 nm的近紫外光激发下，样品的发射光谱在500～700 nm波长范围内存在三个显著的发射峰，分别是603 nm(⁴G_5/2→⁶H_7/2)和650 nm(⁴G_5/2→⁶H_9/2)处较强的红光，以及566 nm(⁴G_5/2→⁶H_5/2)处较弱的绿光。Sm³⁺离子...     

Er3+、Eu3+双掺杂LaOF荧光粉的光学性能研究及防伪应用

有机发光材料可能对人体或环境造成影响,除此之外还有生产成本高、发光易淬灭、发光强度与颜色不易于控制的缺点,因此探索性能优越的稀土发光材料并寻找其应用价值是具有重要意义的。本文基于水热辅助固相法制备出Er³⁺、Eu³⁺离子共掺杂LaOF荧光粉,通过X射线衍射仪(X-ray diffractometer, XRD)、扫描电镜(scanning electron microscope, SEM)和荧光分析仪对不同Er³⁺掺杂浓度下的LaOF∶Eu³⁺荧光粉体的相组成、粒径尺寸、形貌及荧光光谱进行表征与分析。结果表明：在900℃的温度下煅烧,物相由前驱体LaF₃转变为四方相LaOF,且随着Er³⁺掺杂浓度的升高,在365 nm与393 nm波长激发下均呈现出多色可调谐的发光特性,其中365 nm激发下呈现自橙色光向黄色光的转变,而在393 nm光辐射下则由橙色光向品红色光过渡。将Er³⁺、Eu³⁺共掺杂LaOF荧光粉制成...     

Bi3+, Eu 3+, Tb3+ 掺杂Lu3TaO7的发光性能研究

采用固相反应法制备了Bi ³⁺ 、Eu³⁺ 、Tb³⁺ 掺杂的Lu₃TaO₇。测量了样品的X射线衍射谱、激发和发射光谱及荧光衰减曲线。三种离子掺杂的Lu₃TaO₇均呈现出强的荧光发射,其中Bi³⁺具有峰位在431 nm处的一强发射宽带,衰减寿命为16.8 μs,Eu ³⁺ 、Tb ³⁺ 则表现出稀土离子的特征锐发射峰,衰减寿命分别为1.26 ms和1.20 ms。因此,它们均是具有潜在应用前景的重闪烁体材料。     

白光LEDs用(Ba/Sr/Ca)2.9Ce(PO4)3:0.1Eu2+的发光特性

采用高温固相法制备了(Ba/Sr/Ca)_2.9Ce(PO₄)₃:0.1Eu²⁺系列荧光粉,研究了材料的发光特性。在400 nm光激发下,增大x值,Ba_2.9-xSr_xCe(PO₄)₃:0.1Eu²⁺的主发射峰由515 nm红移至540 nm,色坐标从(0.312,0.607)变到(0.376,0.580);随着y值的增大,Ba_2.9-yCa_yCe(PO₄)₃:0.1Eu²⁺的主发射峰由515 nm红移到553 nm,色坐标从(0.312,0.607)变到(0.427,0.535),随z值的增大,Sr_2.9-zCa_zCe(PO₄)₃:0.1Eu²⁺的主发射峰值由540 nm红移...     

Yb3+/Er3+共掺ZnF2粉末上转换发光特性研究

为了研究ZnF₂作为基质材料、稀土离子Yb3+和Er3+共掺摩尔分数不同时的发光性能,采用高温固相法,在820℃时制备稀土掺杂ZnF₂样品,并对各个样品进行上转换发射光谱测试。将激发功率与上转换发射功率进行曲线拟合,确定Yb3+和Er3+光子吸收过程。结果表明,在980nm半导体激光器激发下,样品在可见光区域内存在533nm,555nm和655nm 3个上转换发射峰,发射的红光强度大于绿光强度,吸收光子数目依次为1.73,1.75,1.88,确定3个发射峰均对应于双光子吸收。此研究说明稀土离子掺杂ZnF₂材料将在上转换红色荧光粉领域有重要的应用前景。     

VOLTE容灾机制研究及优化方案

_{本文首先对VOLTE现网网络结构及容灾机制进行研究分析,发现现存容灾机制中存在的缺点和不确定性,针对其中的问题,针对性地进行了深入研究和分析,创新的提出了1种快速容灾抢通方案,以达到提升VOLTE业务运维能力和用户业务感知的目的。}     

Calculation of energy band gaps in quaternary iii/v alloys

The dielectric theory of electronegativity is applied to the calculation of the compositional dependence of the energy band gap for quaternary III/V alloys of type A_l-xB_xC_1-yD_y and A_1-x-yB_xC_yD. The departure from linearity of E_G versus x and y is taken to be the sum of two terms, the intrinsic or virtual crystal term and the extrinsic term due to effects of aperiodicity which for one type of alloy may occur on both sublattices. Rather than simply treating the quaternary as an average of the bounding ternary systems, as has been common in the past, the intrinsic departure from linearity is calculated by assuming E_h,i,C, and D_av to vary linearly with x and y. The result is a smaller intrinsic deviation from linearity and a much better fit to existing data in the system Ga_1-xIn_xAs_1-y P_y. The calculation is also applied to three systems where no data exist but which are of great interest because of their potential application for the fabrication of lattice matched tandem solar cells: Ga_l-xA1_xAs_l-ySb_y. Ga_1-x-yA1_xIn_yAs, and GaAs_1-x-yP_xSb_y.     

新形势下河北移动全业务支撑策略研究

随着铁塔公司的成立及国家在“宽带中国”“提速降费”等一系列通信领域的重大战略实施,全业务运营越来越成为河北移动保持领先,实现卓越的重要支点。基于此河北移动启动大规模综合业务区建设,由传统传输网围绕基站建设转向全业务支撑。河北移动将综合业务区建设与全业务机房的选取统筹安排,建设综合业务区与全业务机房的联络光缆,将综合业务区光缆网成为承载重要集客数据专线和4G拉远站的载体,合理、有序、迅速实现“一张光缆网”的建设,鼎力支撑全业务及4G的发展。     

Nickel silicidation techniques for strained Si1?xGex, Si1?x?yGexCy, and Si1?yCy alloys material-device applications

A nickel silicide process for Si_1-xGe_x, Si_1-x-yGe_xC_y, and Si_1-yC_y alloy materials compatible with Si technology has been developed. Low-resistivity-phase (12–20 μΘ cm) nickel silicides have been obtained for these alloys with different low sheet-resistance temperature windows. The study shows that thin (15–18 nm) silicide layers with high crystalline quality, smooth silicide surface, and smooth interface between silicide and the underlying material are achievable. The technique could be used to combine the benefits of Ni silicide and Si_1-xGe_x, Si_1-x-yGe_xC_y, and Si_1-yC_y alloys. The technique is promising for Si or Si_1-xGe_x, Si_1-x-yGe_xC_y, and Si_1-yC_y alloy-based metal-oxide semiconductor, field-effect transistors (MOSFETs) or other device applications.     

Low pressure metalorganic chemical vapor deposition of InP and related compounds

The low pressure metalorganic chemical vapor deposition epitaxial growth and characterization of InP, Ga_0.47In_0.53 As and Ga_xIn_1-xAs_yP_1-y, lattice-matched to InP substrate are described. The layers were found to have the same etch pit density (EPD) as the substrate. The best mobility obtained for InP was 5300 cm² V⁻¹S⁻¹ at 300 K and 58 900 cm² V⁻¹ S⁻¹ at 77₂K, and for GaInAs was 11900 cm² V⁻¹ S⁻¹ at 300 K, 54 600 cm² V⁻¹ S⁻¹ at 77 K and 90 000 cm V⁻¹S⁻¹ at 2°K. We report the first successful growth of a GaInAs-InP superlattice and the enhanced mobility of a two dimensional electron gas at a GaInAs -InP heterojunction grown by LP-MO CVD. LP MO CVD material has been used for GaInAsPInP, DH lasers emitting at 1.3 um and 1.5 um. These devices exhibit a low threshold current, a slightly higher than liquid phase epitaxy devices and a high differential quantum efficiency of 60%. Fundamental transverse mode oscillation has been achieved up to a power outpout of 10 mW. Threshold currents as low as 200 mA dc have been measured for devices with a stripe width of 9 um and a cavity length of 300 um for emission at 1.5 um. Values of T in the range 64–80 C have been obtained. Preliminary life testing has been carried out at room temperature on a few laser diodes (λ = 1.5μm). Operation at constant current for severalthousand hours has been achieved with no change in the threshold current.     

Transport properties of thermoelectric materials for coolers

The Seebeck coefficient, thermal conductivity, electrical conductivity and Hall coefficient of cooler grade, p-and n-type ternary alloys of Bi₂Te₃-Sb₂Te₃-Sb₂Se₃ were measured between 10 and 300 K. Between 300 K and about 150 K the temperature dependence of the transport properties can be explained by assuming nondegeneracy and a lattice scattering mechanism. The difference between the temperature dependence of the Hall effect in n-and p-type alloys can be explained by the presence of sub-bands of light and heavy holes in the valence band of p-type alloys.     

Characterization of a rapid thermal anneal TiNxOy/TiSi2 contact barrier

In this paper, the physical and electrical properties of a TiN_xO_y/TiSi₂ dual layer contact barrier are reported. The TiN_xO_y/TiSi₂ barrier was formed by rapidly annealing a Ti thin film on Si in an N₂ ambient. During this process, the Ti film surface reacts with N₂ to form a TiN_xO_y skin layer and the bulk of the Ti film reacts with Si to form an underlying TiSi₂ layer. The influences of rapid thermal anneal (RTA) conditions on the TiN_xO_y layer were investigated by varying the RTA temperature from 600 to 1100° C and cycle duration from 30 to 100 s. It is found that the resulting TiN_xO_y and TiSi₂ layer thicknesses are dependent on RTA temperature and the starting Ti thickness. For a starting Ti thickness of 500Å, 150Å thick TiN_xO_y and 800Å thick TiSi₂ are obtained after an RTA at 900° C for 30 s. The TiN_xO_y thickness is limited by a fast diffusion of Si into Ti to form TiSi₂. When a Ti film is deposited on SiO₂, Ti starts to react with SiO₂ from 600° C and a significant reduction of the SiO₂ thickness is observed after an RTA at 900° C. The resulting layer is composed of a surface TiN_xO_y layer followed by a complex layer of titanium oxide and titanium suicide. In addition, when Ti is depos-ited on TiSi₂, thicker TiN_xO_y and TiSi₂ layers are obtained after RTA. This is because the TiSi₂ layer retards the diffusion of Si from the underlying substrate into the Ti layer. NMOSFETs were fabricated using the TiN_xO_y/TiSi₂ as a contact barrier formed by RTA at 900° C for 30 s and a significant reduction of contact resistance was obtained. In addition, electromigration test at a high current density indicated that a significant improvement in mean time to failure (MTF) has been obtained with the barrier.     

基于InP衬底的晶格失配In0.68Ga0.32As的MOCVD生长及其特性研究

采用MOCVD生长技术在InP衬底上成功实现了晶格失配的3μm In0.68 Ga0.32As薄膜生长.通过As组分的改变,利用张应变和压应变交替补偿的InAsxP1-x应变缓冲层结构来释放由于晶格失配所产生的应力,在InP衬底上得到了与In0.68Ga0.32 As晶格匹配的InAsxP1-x“虚拟”衬底,通过对缓冲层厚度的优化,使应力能够在“虚拟”衬底上完全豫弛.通过原子力显微镜(AFM)、高分辨XRD、透射电镜(TEM)和光致发光(PL)等测试分析表明,这种释放应力的方法能够有效提高In0.68 Ga0.32 As外延层的晶体质量.     

The effect of Tl2Te3 on the properties of the solid solution (Sb2Te3)0.75.(Bi2Te3)0.25

The effect on transport properties of the addition of 0.5-5% Tl₂Te₃ to p-type solid solutions of antimony and bismuth tellurides was studied. It was found that the addition of Tl₂Te₃ caused a lessening of the increase of hole concentration as low temperatures were approached, resulting in a slower decrease of the Seebeck coefficient with a decrease in temperature. In partial fulfillment of M.Sc. degree, Hebrew University, Jerusalem. Permanent address, Dept. of Inorganic and Analytical Chemistry, Hebrew University, Jerusalem.     

Processing of large YBa2 Cu3Ox domains for levitation applications by a Nd1+x Ba2−x Cu3 Oy-Seeded melt-growth technique

YBa₂Cu₃O_x domains for levitation applications have been produced by a seeding technology that includes Nd_1+x Ba_2−x Cu₃O_y seeds and melt-processing technologies such as conventional melt-textured growth, melt-texturing with PtO₂ and Y₂BaCuO₅ additions, and the new solid-liquid-melt-growth technology. Large domains (∼20 mm) with high levitation forces (F₁ up to 8.2 N) have been produced. The reproducibility of the results is good, and the capability of producing a large number of pellets in a single batch indicates good potential for the production of large amounts of this material.