ZnO纳米棒在Si衬底上外延生长研究

运用热蒸发ZnO粉末法,以金做催化剂,分别在Si(100)和Si(111)两种基片上外延生长了ZnO纳米棒(样品分别标为1#和2#).通过X射线衍射(XRD)和扫描电子显微镜(SEM)分析,结合ZnO与Si的晶格结构特征,从理论上得出了两个样品的晶格匹配关系.1#样品:[0001]ZnO∥[114]Si,[0001]ZnO∥[1-1-4]Si,[0001]ZnO∥[11-4]Si,[0001]ZnO∥[1-14]Si,失配度为1.54;;2#样品:[0001]ZnO∥[111]Si,[21-1-0]ZnO∥[11-0]Si,[1-21-0]ZnO∥[1-01]Si ,[1-1-20]ZnO∥[011-]Si,失配度为18.12;.研究表明Si衬底对ZnO纳米棒生长方向具有调控作用.     

BaY2F8晶体生长基元与结晶机理的探讨

本文通过对BaY2F8晶体结构的分析,从晶体的生长基元为负离子配位多面体理论出发,对自然冷却条件下BaY2F8晶体自发结晶习性进行了研究,提出了以Ba2+为中心的近八配位十二面体和以Y3+为中心的近八配位十二面体是晶体生长的基元.并根据自发结晶的BaY2F8的XRD,说明了BaY2F8晶体的{200}、{130}、{021}、{330}、{-111}、{111}、{221}、{002}等面族比较发育的原因.本文证实了仲维卓的负离子配位多面体理论对BaY2F8晶体生长的适用性,并对探索新的BaY2F8单晶生长方法有参考作用.     

饲料中补充晶体蛋氨酸和羟基蛋氨酸钙对罗氏沼虾幼虾生长性能的影响

饲料中添加30%鱼粉为对照组饲料和6组试验饲料(分别替代对照组中16.67%、33.33%和50.00%的鱼粉,同一鱼粉替代水平的2组分别添加晶体蛋氨酸和羟基蛋氨酸钙,使其蛋氨酸含量与对照组一致)喂养罗氏沼虾(初始体重为(0.29±0.04) g )10周,研究不同鱼粉替代水平下,分别添加晶体蛋氨酸和羟基蛋氨酸钙对罗氏沼虾幼虾生长性能和血清生化指标的影响.结果表明：复合蛋白源替代对照组16.67%鱼粉并补充羟基蛋氨酸钙组的增重率、特定生长率、蛋白质效率和饲料系数同对照组无显著差异(P>0.05);同一鱼粉替代水平下,羟基蛋氨酸钙组的增重率、特定生长率和蛋白质效率均显著高于晶体蛋氨酸组(P<0.05).血清生化组成的分析结果表明：血清总蛋白含量各处理组之间差异显著(P<0.05),对照组血清谷草转氨酶和谷丙转氨酶活力显著低于其他各组(P<0.05),其中同一替代水平下,饲料中添加羟基蛋氨酸钙组谷草转氨酶和谷丙转氨酶活力低于添加晶体蛋氨酸组.由此可见,与晶体蛋氨酸相比,羟基蛋氨酸钙能更有效提高罗氏沼虾生长性能和饲料利用效率.     

Compositional, structural, optical and electrical characterization of CulnTe2 grown by the tellurization of stoichiometric Cu and in in the liquid phase

A new method to grow single crystals with stoichiometry close to 1:1:2 of CuInTe₂, an important member of the Cu-III-VI₂ family of semiconductors is described. This consists of tellurization in the liquid phase of stoichiometric Cu and In and later solidification under directional freezing. It is found from energy dispersive spectroscopy that the ingots obtained with the evaporation temperature (T_t) of Te at 590 and 635°C were very close to the ideal stoichiometry 1:1:2. Samples of all ingots obtained with T_t between 530 and 690°C, as studied by x-ray and differential thermal analysis, were of single phase having chalcopyrite structure and p-type conductivity. Optical and electrical characterization of different ingots were made. The acceptor ionization energy E_A and the density of states effective mass m _p ^* of the holes are estimated from the temperature dependence of the hole concentration p in samples of different ingots. m _p ^* = (0.78 ± 0.02) m_e agrees quite well with the reported value. From a combined analysis of the variation of E_A with p^1/3 and the knowledge of molecularity and valence stoichiometry of each sample, it is established that the shallow acceptor level observed in different samples with E_A (0) ⋍ 30 meV is due to V_In.     

Penta‐Twinned Copper Nanorods: Facile Synthesis via Seed‐Mediated Growth and Their Tunable Plasmonic Properties

The use of seed‐mediated growth as a versatile approach to the synthesis of penta‐twinned Cu nanorods with uniform diameters and controllable aspect ratios is reported. The success of this approach relies on our recent synthesis of uniform Pd decahedra, with sizes in the range of 6–20 nm. The Pd decahedral seeds can direct the heterogeneous nucleation and growth of Cu along the fivefold axis to produce nanorods with uniform diameters defined by the lateral dimension of the original seeds. Due to a large mismatch in the lattice constants between Cu and Pd (7.1%), the deposited Cu is forced to grow along one side of the Pd decahedral seed, generating a nanorod with an asymmetric distribution of Cu, with the Pd seed situated at one of the two ends. According to extinction spectra, the as‐obtained Cu nanorods can be stored in water under the ambient conditions for at least six months without noticeable degradation. This excellent stability allows us to systematically investigate the size‐dependent surface plasmon resonance properties of the penta‐twinned Cu nanorods. With the nanorod transverse modes positioned at 560 nm, the longitudinal modes can be readily tuned from the visible to the near‐infrared region by controlling the aspect ratio.     

雷达可靠性增长

提出雷达可靠性的增长应从提高“三化”和抗恶劣环境设计入手 ,加强环境应力筛选和可靠性增长管理的试验。     

Monolayer MoS2 Dendrites on a Symmetry‐Disparate SrTiO3 (001) Substrate: Formation Mechanism and Interface Interaction

Dendritic patterns generated in non‐equilibrium growth processes are prevalent in nature while their formation mechanisms are far from fully understood. Here, we report a coverage‐dependent fractal degree evolution of monolayer 2H‐MoS₂ dendrites synthesized on a symmetry‐disparate substrate of SrTiO₃ (001). Surprisingly, various characterizations have revealed that the monolayer dendrites featured with orthogonal backbones are single crystalline, possessing both peculiar adlayer‐substrate interaction and abnormal indirect bandgap on SrTiO₃ (001). Further theoretical calculations indicate that a prominent diffusion anisotropy of monomer precursors, combined with the disparate adlayer‐substrate symmetry, determine the diffusion‐limited aggregation of MoS₂ towards dendritic shapes. This work provides brand‐new insights in the morphological engineering of two‐dimensional atomic crystals, and contributes greatly to an in‐depth understanding of the detailed dynamics in non‐equilibrium crystal growth.     

利用水平热壁CVD法生长的3C-SiC/Si的均匀性

利用新改进的水平低压热壁CVD设备,改变生长时的压力和H2流速,在50mm的Si(100)和(111)衬底上获得了3C-SiC外延膜,并对外延膜的结构均匀性、电学均匀性和厚度均匀性进行了分析.X射线衍射图中出现了强的3C-SiC的特征峰,其中3C-SiC的(200)和(111)峰的半高宽分别为0.41°和0.21°.3C-SiC外延膜方块电阻的均匀性最好可达2.15%.厚度均匀性可达±5.7%(σ/mean值).     

A Simple Hydrothermal Method for the Growth of ZnO Crystals

ZnO microstructures have been grown from zinc chloride (ZnCl₂) and ammonia solution at 100 °C for 1 – 24 hours. X‐ray diffraction, scanning electron microscope and field‐emission scanning microscope were utilized to investigate the structural properties and morphology of the ZnO crystals. Structural investigations show that phase‐pure hexagonal structure ZnO has been successfully synthesized, and the hexagonal structure ZnO can be achieved in solutions with an appropriate range of concentrations. Under our experimental conditions, several different morphologies of ZnO structures were obtained, including flower‐like and bar flower‐like. The relationship between the morphology and experimental conditions are discussed.     

Stationary states of crystal growth in three dimensions

A new Markov process describing crystal growth in three dimensions is introduced. States of the process are configurations of the crystal surface, which has a terrace-edge-kink structure. The states are continuous along edges but discrete across edges, in accordance with the very different rates for the two types of captures of particles. Stationary distributions, describing steady crystal growth, are found in general. To our knowledge, these are the first examples of stationary distributions for layered crystal growth in three dimensions. The steady growth rate and other quantities are obtained explicitly for two interacting edges. For many interacting edges, growth behavior is determined (a) in various asymptotic regimes including thermodynamic limits, (b) via simulations, and (c) using series (cluster) expansions in the slope of the surface, the first three coefficients being computed. The theoretical growth rates show a marked dependence on surface dimensions. This may contribute to the size dependence and dispersion in the observed growth rate of small crystals.