物理气相传输法生长氧化锌晶体

以高纯氧化锌粉为升华源,采用物理气相传输法(PVT)法在1500℃下生长出了ZnO多晶体,生长速率达0.24 mm/h.样品XRD测试和拉曼分析表明,无籽晶自发成核生长的ZnO多晶体不仅具有六方纤锌矿结构,而且具有c轴方向择优生长特征.实验结果表明了PVT法可以进行大尺寸ZnO晶体的生长,并且可以达到0.2 mm/h以上的生长速率.     

凝胶-燃烧-熔盐法制备Ca2-xAl2SiO7∶Dyx3+白光荧光粉

采用凝胶-燃烧-熔盐法合成了Ca2-xAl2SiO7∶Dyx3+(x =0.01、0.02、0.03、0.04、0.05)白光荧光粉,探讨了Dy3的掺杂量对荧光粉发光性能的影响,通过X射线衍射仪、扫描电子显微镜和荧光光谱仪对样品进行了测试表征.结果表明:所得Ca1.97Al2SiO7∶Dy0.033+样品为四方钙铝黄长石结构,平均粒径在0.9～1 μm之间;该样品的激发光谱由一组尖锐的激发峰组成,对应于Dy3+的6H15/2→6P3/2(321 nm)、6H15/2→6P7/2(345 nm)、6H15/2→6P5/2(363nm)、6H15/2→4F7/2(384 nm)、6H15/2→4G11/2(425 nm)、6H15/2→4I15/2(452 nm)和6H15/2→4F9/2(470 nm)跃迁,发射光谱由位于477 nm的蓝光发射和580 nm的黄光发射组成,对应于Dy3+的49F/2→6q5/2(477 nm) 和4 F9/2→6H13/2(580nm)跃迁,其CIE1931色坐标为(x=0.3017,y =0.3011),接近于理想的白光(x=0.333,y=0.333);当Dy3+掺杂量大于0.03时出现浓度猝灭,这主要是电偶极-电偶极的相互作用引起的.     

Out-of-plane shear flow effects on fast magnetic reconnection in a two-dimensional hybrid simulation model

The effects of out-of-plane shear flows on fast magnetic reconnection are numerically investigated by a twodimensional(2D)hybrid model in an initial Harris sheet equilibrium with flows.The equilibrium and driven shear flows out of the 2D reconnection plane with symmetric and antisymmetric profiles respectively are used in the simulation.It is found that the out-of-plane flows with shears in-plane can change the quadrupolar structure of the out-of-plane magnetic field and,therefore,modify the growth rate of magnetic reconnection.Furthermore,the driven flow varying along the anti-parallel magnetic field can either enhance or reduce the reconnection rate as the direction of flow changes.Secondary islands are also generated in the process with converting the initial X-point into an O-point.     

Numerical study on discharge characteristics influenced by secondary electron emission in capacitive RF argon glow discharges by fluid modeling

A one-dimensional(1D) fluid model of capacitive RF argon glow discharges between two parallel-plate electrodes at low pressure is employed. The influence of the secondary electron emission on the plasma characteristics in the discharges is investigated numerically by the model. The results show that as the secondary electron emission coefficient increases,the cycle-averaged electric field has almost no change; the cycle-averaged electron temperature in the bulk plasma almost does not change, but it increases in the two sheath regions; the cycle-averaged ionization rate, electron density, electron current density, ion current density, and total current density all increase. Also, the cycle-averaged secondary electron fluxes on the surfaces of the electrodes increase as the secondary electron emission coefficient increases. The evolutions of the electron flux, the secondary electron flux and the ion flux on the powered electrode increase as the secondary electron emission coefficient increases. The cycle-averaged electron pressure heating, electron Ohmic heating, electron heating, and ion heating in the two sheath regions increase as the secondary electron emission coefficient increases. The cycle-averaged electron energy loss increases with increasing secondary electron emission coefficient.     

含有圆孔平板电极结构的双凸液体透镜的设计与分析

基于平行平板电极的变焦液体透镜的有关研究,通过应用介电泳效应,提出了一种含有圆孔平板电极结构的双凸液体透镜模型,是一种新型的三层液体透镜结构.利用Comsol,Matlab和Zemax软件仿真分析了该模型在不同电压下的面型变化与成像光路,得出其变焦范围为22.6—15.9 mm,并对制备的器件进行具体的实验分析,获得了不同电压下双凸液体透镜的液滴上下界面面型和该透镜的变焦范围23.8—17.5 mm,与仿真结果基本一致,而且其成像分辨率可达到45.255 lp/mm.结果表明,所提出的这种新型三层液体结构的双凸液体透镜具有结构简单、易于实现的特点,而且具备良好的成像质量.     

强流脉冲离子束辐照双层靶能量沉积的数值模拟

利用拟合实验测得的TEMP Ⅱ型加速器磁绝缘二极管电压波形及其焦点附近束流密度曲线,建立了Gauss分布模型.采用Monte Carlo方法研究了强流脉冲离子束与铝材镀有不同厚度金膜的双层靶(金膜与铝材合称为双层靶)之间的相互作用,模拟了能量沉积的演化过程和随不同金膜厚度的变化情况.对脉冲离子束强化薄膜粘结性进行了探讨. 关键词： 强流脉冲离子束 双层靶 能量沉积 Monte Carlo方法     

Numerical Study on Characteristics of Argon Radio-Frequency Glow Discharge with Varying gas Pressure

A one-dimensional fluid simulation on argon rf glow discharge with varying linearly gas pressure from 1 Torr to 100 Tort is performed. The model based on mass conservation equations for electron and ion under diffusion and mobility approximation, and the electron energy conservation equation is solved numerically by finite volume method. The numerical results show that a uniform plasma with high density can be obtained from rf glow discharge with varying gas pressure, and the density of plasma becomes higher as the gas pressure varies from 1 Tort to 100 Tort. It is also shown that in the range of the gas pressure from 1 Tort to 100 Tort with the slower rate of varying gas pressure, higher density of plasma can be obtained.     

Effect of Thermionic Emission on Dust-Acoustic Solitons in a Dust-Electron Plasma

The effects of thermionic emission on dust-acoustic solitons with a very small but finite amplitude in a dustelectron plasma are studied using the reductive perturbation technique. The self-consistent variation of dust charge is taken into account. It is shown that the thermionic emission could significantly increase the dust positive charge. The dependences of the phase velocity, amplitude, and width of such solitons on the dust temperature and the dust work function of dust material are plotted and discussed.     

PdAg/MIL-101(Fe)催化NaBH4水解制氢

将PdAg纳米颗粒负载到MIL-101(Fe)上作为硼氢化钠水解制氢的催化剂。采用XRD、TEM、HRTEM、XPS、SEM和EDS等方法对催化剂PdAg/MIL-101(Fe)的结构进行了表征。PdAg/MIL-101(Fe)在硼氢化钠水解制氢中表现出较高的催化活性,在温和的条件下水解制氢最大速率为2.60 L·min^–1·g_cat.^–1。详细研究了反应温度、催化剂用量、氢氧化钠和硼氢化钠浓度对该催化反应的影响规律。结果发现,制氢速率很大程度上依赖于反应温度,随着反应温度的升高,制氢速率明显增加,制氢的表观活化能为54.89 kJ·mol^–1。该催化剂重用性能好,5次循环后仍能保持活性。     

含铕配合物的有机电致发光器件的光伏效应

自从1986年Ｔａｎｇ发表了双层有机电致发光器件有光伏效应[1]以来,人们就一直对有机器件的光伏效应有浓厚的兴趣,特别是近年来有大量的文章报道有机器件的光伏效应。在这些报道中,使用材料中有用聚苯乙炔及其衍生物的[2,3],有用Ｃ60做电子受体的[4],但这些研究都与电致发光无关,仅研究了光电转换特性,我们研究组首次报道了电子给体发光,电子受体稀土配合物不发光的有机光伏器件[5]。本文就是在此基础上进一步研究铕配合物ＯＥＬ器件的光伏效应。铕配合物ＯＥＬ器件不仅仅有利于利用配体三重态能量、提高能量转换效率的潜力,而且中心离…