Formability and properties of self-standing clay film by montmorillonite with different interlayer cations

Influences of exchangeable interlayer cations were investigated on self-standing film formability, film morphology, and properties of the clay films such as flexibility and gas barrier property. Ion-exchanged montmorillonite samples were prepared by a cation exchange from naturally bearing cation, mostly Na⁺, to Li⁺, Mg²⁺, Ca²⁺, Al³⁺, and Fe^{2+, 3+}. Self-standing films were prepared from aqueous colloidal dispersions of these montmorillonite samples with no additives. The montmorillonite samples with monovalent or divalent cation formed flat self-standing films while the Al-montmorillonite sample produced a distorted film. The Fe-montmorillonite sample formed many separated reddish-brown rod-shaped pieces. Clay film microstructures were different with interlayer cations. The films with monovalent interlayer cations were constructed by the stacking of units with delicately waved thin clay sheets in the whole film, but other films show different morphologies between the upper side and lower side; the upper side is laminated with thin sheets; the lower side is laminated with large thick sheets.The self-standing films’ flexibility and gas barrier property differed according to the interlayer cations. These properties were good in cases of samples with monovalent cations. The innumerable short wave and sheet thinness are considered to foster good flexibility and gas barrier properties. The differences in film formability and properties of the films are attributable to different swellability among samples with different interlayer cations. The montmorillonite samples with monovalent cations swell sufficiently by water, but those with polyvalent cations swell poorly. In the latter case, clay crystals aggregate in water, then the aggregate grows into large particles, creating a film with large particles.     

薄膜电容直流耐压测试仪的原理与实现

介绍了薄膜电容分选机中直流耐压测试仪的开发背景与意义,阐述了直流耐压测试的原理与结构,对高压条件下的充电过程、放电过程,回路控制、检测和抗干扰技术等主要设计思想与理论进行详细说明。另外还对客户工厂中的应用情况以及存在问题做了简单概括。     

ZrO2薄膜微结构及其抗激光损伤特性研究

通过分析ZrO2薄膜电子束沉积时氧压、衬底转动及温度对薄膜相结构、晶粒尺寸和粗糙度的影响,对ZrO2薄膜微结构特性与抗激光诱导损伤性能的关系进行了研究.ZrO2薄膜衬底无转动沉积时晶体以四方相为主,而转动沉积时形成具有较高激光损伤阈值的单斜相结构.薄膜晶粒尺寸和粗糙度均随氧压的升高而减小,四方相受氧压影响变化明显高于单斜相,氧压的继续升高使多晶形态向非晶形态逐渐转变.多晶结构的损伤阈值随着晶粒尺寸的减小而增高,薄膜表面粗糙度随着沉积温度的升高略有增加,且多晶结构的损伤阈值明显要高于非晶结构,ZrO2薄膜损伤阈值(E)与粗糙度(σ)基本符合关系:Eσα=β(α=1.41,β=2.25).     

带电磁屏蔽膜的刚挠结合印制板脱膜改善

高频高速挠性或刚挠结合印制电路板为抑制电磁干扰和减少信号传输损耗,在板面贴合电磁屏蔽膜.目前按传统工艺加工,刚挠结合印制板压合后出现电磁屏蔽膜掉膜而致品质不良,无法满足品质需求.本文通过对电磁屏蔽膜使用多种方案进行研究,有效地改善电磁屏蔽膜在制作过程中出现掉膜问题,为后续带电磁屏蔽膜刚挠结合印制板提供加工技术基础.     

In-situ and ex-situ ZnO nanorod growth on ZnO homo-buffer layers

Vertically well-aligned ZnO nanorods were fabricated in-situ and ex-situ on ZnO homo-buffer layers using catalyst-free metal-organic chemical vapor deposition. Field-emission electron microscopy measurements demonstrated that the nanorods were well aligned and had a uniform diameter of 70–100 nm depending on the growth temperature, irrespective of growth conditions, in-situ and ex-situ. X-ray diffraction measurements demonstrated that the ZnO nanorods and the ZnO buffer layers had a wurtzite structure, and that the crystal quality of the nanorods grown on a smooth surface was better than that of the nanorods grown on a rough surface. Field-emission transmission electron microscopy measurements revealed the presence of a disordered layer at the interface of the nanorod and the buffer layer.     

Encapsulation of dye molecules into mesoporous polymer resin and mesoporous polymer-silica films by an evaporation-induced self-assembly method

Polymer resin and polymer-silica films with highly ordered mesostructure have been used as host materials to encapsulate DCM (4-(dicyanomethylene) -2-methyl-6-(4-dimethylaminostyryl)-4h-pyran), a kind of fluorescent dye, through evaporation-induced self-assembly method (EISA). After encapsulation, the composites show significant blue-shift in photoluminescence (PL) spectra. Particularly, by changing the excitation wavelength, the samples show different emission bands. These phenomena are related to the mesostructure and the positions of DCM molecules in the host.     

Elucidating surface properties of dry-etched ZnO using H2/CH4 and H2/CH4/Ar plasma

This paper reports a study of reactive ion etching (RIE) of n-ZnO in H₂/CH₄ and H₂/CH₄/Ar gas mixtures. Variables in the experiment were gas flow ratios, radio-frequency (rf) plasma power, and total pressure. Structural and electrical parameters of the etched surfaces and films were determined. Both the highest surface roughness and highest etching rate of ZnO films were obtained with a maximum rf power of 300 W, but at different gas flow ratios and working pressures. These results were expected because increasing the rf power increased the bond-breaking efficiency of ZnO. The highest degree of surface roughness was a result of pure physical etching by H₂ gas without mixed CH₄ gas. The highest etching rate was obtained from physical etching of H₂/Ar species associated with chemical reaction of CH₄ species. Additionally, the H₂/CH₄/Ar plasma treatment drastically decreased the specific contact and sheet resistance of the ZnO films. These results indicated that etching the ZnO film had roughened the surface and reduced its resistivity to ohmic contact, supporting the application of a roughened transparent contact layer (TCL) in light-emitting diodes (LEDs).     

核果类水果干物质含量近红外无损检测研究

以桃、李及杏果实为材料,研究其干物质含量的近红外漫反射无损检测模型的建立方法。研究发现,桃、李及杏果实干物质预测模型的决定系数(r_P~2)分别为0.901、0.909及0.923,预测均方根误差(RMSEP)分别为0.365、0.401及0.465,相对分析误差(RPD_P)分别达2.9、3.2及3.1以上。结果表明,近红外漫反射光谱可用于准确、快速、无损定量3种水果中干物质含量。     

垂直纵槽管强化膜状冷凝换热研究

用数值方法对饱和蒸汽在纵槽管表面的冷凝换热性能进行了研究。以发展段为主要研究对象,对模型进行了适当的简化,建立了液膜的基本方程,并与二维导热方程耦合,用Runge-Kutta法和有限元法解方程,通过迭代,分别得到了传热量以及最大液膜厚度与坐标z的关系式。最后用文中的分析方法,研究了制冷剂R-113在余弦形纵槽管上的冷凝,并与文献中的实验值做了对比。结果表明,纵槽管的长度(无除液盘时)或除液盘间距应小于最大有效管长,以便纵槽管在温差较大时仍具有较好的换热效果;在温差较小时,数值分析结果与文献中的实验数据吻合较好,证明本文的分析方法具有可行性。     

The influence of the AlN film texture on the wet chemical etching

The influence of the aluminum nitride (AlN) film texture on the chemical etching in KOH solution was invested. The AlN films with the different texture and crystal quality were prepared by sputtering. It is found that the chemical etching behaviors, including the etch rate, the activation energy, the surface morphology and the anisotropy, are strongly dependent on the film texture. There is a faster etching in the case of mixed (1 0 0) and (0 0 2) texture and a lower rate in the case of only (0 0 2) texture. The etch rate also decreases with the crystal quality. The sample with the only (0 0 2) texture forms discontinuous column structure after etching and exhibits lower porosity compared to that of the mixed (1 0 0) and (0 0 2) texture. Due to the strong anisotropy of the AlN wurtzite structure, the morphology of the film deposited at 700 °C shows the homogeneous pyramid shape after etching. The cross-section micrographs of etching patterns indicate that the anisotropy of the chemical etching is improved with the improving of the crystal quality.