硝基甲烷中爆轰波绕射的实验研究和数值模拟

叙述了对硝基甲烷中拐角分别为６０、９０、１２０三种情形的爆轰波绕射现象进行的实验研究。实验上观测到爆轰波绕过９０、１２０拐角时有未反应的死区，而且拐角增大时死区变大，绕射爆轰波可以近似地按爆心在拐角顶点附近变化的散心爆轰波看待。从数值模拟和理论分析得出，爆轰波绕射时硝基甲烷的化学反应不同于正常爆轰，拐角顶点附近各处反应速率不同，出现部分反应区和未反应区。     

非平衡磁控溅射沉积类石墨膜及其摩擦磨损性能研究

利用全封闭非平衡磁控溅射技术制备了高硬度类石墨膜，对不同工艺所制备的薄膜进行了微观分析，测定了薄膜的厚度、膜基结合强度和硬度，并考察了薄膜的摩擦学性能和腐蚀性能．结果表明：采用全封闭非平衡磁控溅射方法制备的以sp^2杂化为主的类石墨膜具有高硬度、低摩擦系数和良好的抗磨及抗腐蚀性能；摩擦系数随载荷的增大而减小，而磨损率同硬度呈反比关系；加入适量Cr可软化薄膜，提高膜基结合强度，从而优化薄膜的性能．     

Influence of Reactive Compatibilizer on the Morphology,Rheological, and Mechanical Properties of Recycled Poly(Ethylene Terephthalate)/Polyamide 6 Blends

Recycled poly(ethylene terephthalate) (R-PET) and virgin polyamide 6 (PA6) blends compatibilized with glycidyl methacrylate grafted poly(ethylene-octene) (POE-g-GMA) were melt blended. The morphological, rheological and mechanical properties of the prepared blends were investigated by scanning electron microscopy, rheology, and an electromechanical testing instrument, respectively. All of the blends showed a droplet dispersion type morphology, and the PA6 particle size decreased with increase in the POE-g-GMA concentration. The storage modulus (G′), loss modulus (G′′), and complex viscosity (η*) of the blends significantly increased at low frequency with the addition of POE-g-GMA. In addition, ‘‘Cole-Cole’’ plots showed that the elasticity of the blends was also increased by raising the compatibilizer dosage. It was also found that 10 wt% of POE-g-GMA caused 88.46 and 171.05% increments in Charpy impact strength and elongation at break with only a 21.66% decrement in tensile strength.     

Time-dependent quantum wave packet and quasiclassical trajectory studies of the Au(2S) + H2(X1∑+g) → AuH(X1∑+g) + H(2S) reaction

The time-dependent quantum wave packet (TDWP) and quasiclassical trajectory calculations (QCT) are carried out for the Au(²S) + H₂(X¹∑⁺_g) → AuH(X¹∑⁺_g) + H(²S) reaction on a global potential energy surface. The reaction probabilities at a series of J values, integral cross sections (ICSs) and differential cross sections of the title reaction are calculated by the TDWP method. For reaction probabilities, there are a mass of sharp oscillations at low collision energy, which can be attributed to resonances supported by the potential well. Due to the endothermicity of the title reaction, the total ICS shows a threshold about 1.53 eV. In order to further investigate the reactive mechanism, the lifetime of complex is calculated by QCT method. At the low collision energy, most intermediate complexes are long lived, which implies that the reaction is governed by indirect reactive mechanism. With the collision energy increasing, the direct reactive mechanism occupies the dominant position. Due to the change of the reactive mechanism, the angular distribution shifts toward the forward direction with collision energy increasing. The isotopic variant, Au + D₂→AuD + D reaction, is also calculated by TDWP method. The calculated reaction probabilities and ICSs show that the isotope effect reduces the reactivity.     

Low-voltage blue light emission from n-ZnO/p-GaN heterojunction formed by RF magnetron sputtering method

High quality n-ZnO/p-GaN heterojunction was fabricated by growing highly crystalline ZnO epitaxial films on commercial p-type GaN substrates via radio frequency (RF) magnetron sputtering. Low-voltage blue light emitting diode with a turn-on voltage of ∼2.5 V from the n-ZnO/p-GaN heterojunction was demonstrated. The diode gives a bright blue light emission located at ∼460 nm and a low threshold voltage of 2.7 V for emission. Based on the results of the photoluminescence (PL) and electroluminescence (EL) spectra, the origins of the EL emissions were studied in the light of energy band diagrams of ZnO–GaN heterojunction, and may attribute to the radiative recombination of the holes in p-GaN and the electrons injected from n-ZnO, which almost happened on the side of p-GaN layer. These results may have important implications for developing short wavelength optoelectronic devices.     

高速率沉积磁控溅射技术制备Ge点的退火生长研究

采用磁控溅射技术在Si衬底上以350?C沉积14 nm的非晶Ge薄膜,通过退火改变系统生长热能,实现了低维Ge/Si点的生长.利用原子力显微镜(AFM)和拉曼(Raman)光谱所获得的形貌和声子振动信息,对Ge点的形成机理和演变规律进行了研究.实验结果表明:在675?C退火30 min后,非晶Ge薄膜转变为密度高达8.5×109cm-2的Ge点.通过Ostwald熟化理论、表面扩散模型和对激活能的计算,很好地解释了退火过程中,Ge原子在Si表面迁移、最终形成纳米点的行为.研究结果表明用高速沉积磁控溅射配合热退火制备Ge/Si纳米点的方法,可为自组织量子点生长实验提供一定的理论支撑.     

N2流量对N掺杂MgZnO薄膜结构和性能的影响

利用射频磁控溅射方法,使用Mg_{0. 04}Zn_0.96O 陶瓷靶材,选用不同流量比的氮气和氩气混和气体作为溅射气体,在石英基片上生长N掺杂Mg_xZn_1-xO合金薄膜。研究了氮流量比对薄膜组分、结构、形貌、电学性质和拉曼光谱的影响。结果显示：随着溅射气氛中氮流量比的增加,薄膜中Mg含量增加,薄膜表面颗粒尺寸减小,结晶质量变差,电阻率逐渐增大,导电类型发生转变。在氮流量比为20%时,获得了最好的p型导电薄膜。另外,随着氮流量比的增加,拉曼光谱中与N_O相关的位于272 cm^-1、642 cm^-1左右的振动峰逐渐增强,表明N_O的浓度随着氮流量比的加大而有所增加。     

不同氧气含量下镍铬系平板集热器选择性吸收薄膜的制备和性能表征

采用双极脉冲磁控溅射系统,在不同氧气含量的氩氧混合气体中制备了单层镍-铬金属-电介质复合光谱选择性吸收薄膜。采用X射线衍射仪(XRD)、激光共焦显微拉曼光谱仪、椭偏仪和紫外-可见-近红外分光光度计分别对薄膜的物相结构和光学特性进行了表征。结果表明:实验获得了由金属镍和镍、铬的氧化物(NiO、Cr2O3)组成的复合膜,薄膜对300~1 200 nm波段的太阳光有较强的吸收,而对波长大于1 200 nm的太阳光则吸收较弱,具有良好的光谱选择性,可用作高效太阳光谱选择性吸收涂层。     

双注磁控注入电子枪

为了增加回旋管的功率,采用双注磁控注入电子枪产生相对论电子注。与双阳极磁控注入电子枪相比,双注磁控注入电子枪产生双束电子注,在不影响电子注质量的基础上,增加电子枪的电流;电子枪产生相同电流时,双注磁控注入电子枪电子注电流小,电子注电子之间的空间电荷效应小,能够降低电子注的速度零散,提高电子注的质量。采用MAGIC软件数值模拟双注磁控注入电子枪,设计出一支大束流、低速度零散的双注磁控注入电子枪。     

磁控溅射制备微球表面金属Mo涂层的研究

利用磁控溅射制备了各种工艺参数不同的微球表面金属Mo涂层样品,并通过白光干涉仪和扫描电子显微镜对样品的表面及剖面进行了系统的测试分析。分别探究了溅射工作气压和沉积制备时间对微球表面Mo涂层表面形貌以及结晶质量的影响规律。结果表明通过优化工艺参数可制备微球直径约为800μm、涂层厚度为3.5μm到14.1μm、厚度均匀性良好的微球表面Mo涂层。Mo涂层中的晶粒呈现出柱状结构致密堆积在一起,且随涂层的厚度增加晶粒间空隙增大。