Microtopographical studies of prism faces of potassium dihydrogen phosphate crystals

Surface structures on prism faces of potassium dihydrogen phosphate crystals grown from aqueous solutions and also by gel method are described and illustrated. Density of growth centres increases as the supersaturation of the mother liquor is increased. Gel grown crystals predominantly show rectangular growth hillocks on their prism faces. In the needle shaped crystals further nucleation extends predominantly along theC axis than at right angles to it. Influence of misoriented guest microcrystals on the growth of the prism faces is described.     

渥拉斯顿棱镜在不同方式组合下的光路特性分析

分析了具有相同结构角的两个渥拉斯顿棱镜在不同方式组合下的光路特性。给出了分束角与结构角的关系表达式,同时也给出了分束角与结构角的关系曲线。使用He Ne激光器(波长λ=633nm)对两个结构角S=27°的渥拉斯顿棱镜在四种不同组合方式下的光路进行了测试。结果表明,测试结果与理论计算完全相符。     

棱镜夹具设计

阐述了夹具设计的意义和加工方法的选择原则。介绍了夹具上盘的加工方法和对夹具设计的要求 ,并通过对半五角棱镜和斯米特屋脊棱镜的夹具设计实例 ,讨论了一般夹具的设计思想、依据和步聚     

Ion Optical Methods - Means to Improve Performance of Mass Spectrometers Designed for Isotopic or Chemical Analysis

Abstract

To improve performances of mass spectrometers dedicated to isotopic or chemical analysis, the methods of the ion optics are to be used. To apply the transfer matrix method of ion optics in mass spectrometer design, the matrix elements of various mass analyzers as Wien filters and crossed field sectors, of energy analyzers as electric prisms, were presented. These elements result from ion trajectory calculations representing solutions of the Euler–Lagrange equations. The basic parameters of an unconventional double focusing mass spectrometer were calculated and compared with those of classical design instruments.     

Synthesis and properties of ZnO hexagonal prisms synthesized on MgO-coated Si (111) substrates

ZnO hexagonal prisms have grown on MgO-coated Si (111) substrates by chemical vapor deposition. The process has two steps : the preparation of MgO-coated Si (111) substrates and the preparation of uniform ZnO hexagonal prisms. Some nucleation sites are provided on the Si substrates by the MgO layers, which have the capability to improve the growth of ZnO prisms in the heteroepitaxy. The prisms are single crystals with a preferential growth along the c axis and they are well-faceted at both the end and side surfaces. Room-temperature photoluminescence measurement of these ZnO prisms have shown a strong ultraviolet (UV) emission band centered at 393 nm and a weak green emission band centered at 507 nm, which may be provide an improvement in novel ultraviolet light-emitting devices. In addition, a possible mechanism for the prism growth is proposed based on the analysis by electron microscopy.     

焊接结构应力场计算中的一类五面体可变节点等参单元

本文应用三维有限元理论，构造了一类五面体６～１５节点等参单元的形函数，提出了在五面体单元内的Ｇａｕｓｓ积分处理方法，建立了相应的单元刚度矩阵。这类单元的节点可以在６～１５之间任意选择。将其与ＳＡＰ５中的六面体８～２１节点等参单元匹配，计算了对接板接头的理论应力集中系数。经与有关文献结果比较表明：这类单元适合于计算焊接结构的应力场，并且具有良好的精度。     

单色仪定标曲线的非线性拟合简

采用两种方案对WDF棱镜单色仪的定标曲线进行非线性拟合。通过实验找出棱镜的折射率与TT鼓轮的关系,得到利用科希公式拟合定标曲线的可行性方案;利用高阶多项式对定标曲线进行拟合,运用统计的方法探讨不同的拟合阶数对拟合结果的影响,并得到了最佳的拟合阶数和高精度的拟合结果。     

三棱镜在分光计载物台上摆放位置的研究

讨论在反射法测量三棱镜顶角的实验中,三棱镜在分光计载物台上摆放位置对测量的影响,并提出三棱镜在载物台上的最佳摆放位置。     

六棱柱状多晶γ-Al2O3的制备、表征及其形成机制研究

以AlCl₃·6H₂O为前驱物,在氨水介质中用水热法制备了具有新颖形貌特征的六棱柱状多晶γ-Al₂O₃颗粒。采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)及N₂物理吸脱附等方法对所制备的γ-Al₂O₃颗粒进行了表征,并对其形貌形成机制进行了分析。结果表明,铝前驱物在氨水介质中通过水热处理后,经焙烧可以形成形貌规整的六棱柱状γ-Al₂O₃颗粒,其边长与长度分别约为0.3 μm和2.5 μm。TEM图片显示,六棱柱颗粒是由尺寸在10 nm左右的粒子聚集而成,因而具有多晶γ相特征。所制备的γ-Al₂O₃材料具有发达的孔隙结构,比表面积为274 cm²/g,孔容为0.51 cm³/g,孔径集中分布在5.5 nm周围。研究发现,γ-Al₂O₃六棱柱形貌的形成机制与AlOOH二次粒子在NH₄⁺正电荷作用下发生的最稳态排列形式具有密切的关联。     

Switchable photonic crystal for polymer dispersed liquid crystal

Single-prism systems are used to fabricate electrically switchable Photonic Crystal (PhC) structures in Polymer Dispersed Liquid Crystal (PDLC) films. The optical configuration is simple, stable and repeatable. A good agreement between theoretical and experimental results is obtained for the PhC structures. Hexagonal far-field diffraction patterns and electrical switching characteristics are also investigated. The smallest droplets of liquid crystals are 10 nm in diameter. The switching voltage can be decreased to 13.3 V/μm.