The application of the concept of reaction layer to the study of electrode processes coupled with the second-order chemical reactions at microelectrodes under steady-state conditions

Under steady-state conditions, the current equations of the second-order EC, ECE and DISPI reactions at microdisk, microspherical and microring electrodes are derived with the aid of the concept of the reaction layer. The conditions under which these equations would be valid are also discussed. Using these equations, methods to determine the kinetic parameters for the second-order EC, ECE and DISPI reactions are presented. The reduction of 2,6-diphenyl-pyrylium cation and oxidation of triphenylamine were investigated as examples of the second-order EC and ECE reactions.     

双电层相互重叠时蒙脱胶体表面阴离子的负吸附

本文用Ag-AgCl电极判断平衡,测定双电层处于不同重叠程度下肢体表面阴离子的负吸附量Γ.结果表明,胶体表面双电层相互重叠程度可由两胶体表面间的中点电位φd与外Helmhotz面处的电位φd之比表征;阴离子负吸附随双电层重叠程度和电解质浓度的增加而显著减小.     

Processing and characterization of Pb(Mg,Nb)O3-PbTiO3 thin films from metal alkoxide-derived gels

The sol-gel processing is one of promising methods to fabricate well-derived integrated thin films at relatively low temperature. Ferroelectric niobates films do afford the possibilities for adding the values by the hybridization with semiconductor and/or electro-optic systems. The molecular level designing of the precursor solution was stressed as well as the control of key processing factors. The advantages of this sol-gel have been extended to prepare the ferroelectric Pb(Mg, Nb)O₃-PbTiO₃ solid solution films integrated on Si wafers. The crystallization of the films with desired crystal structure could be promoted by the controlled partial hydrolysis of designed alkoxide solution in the intermediate state and the pre-heated treatment of alkoxide-derived films in flow of water vapor and oxygen gas mixture.     

Electric conductivity in a fibrous porous medium with thin but polarized double layers

The electric conduction in the fibrous medium constructed by a homogeneous array of parallel, identical, charged, circular cylinders having an arbitrary zeta potential filled with the solution of a symmetrically charged electrolyte is analytically examined. The thickness of the electric double layers surrounding the dielectric cylinders is assumed to be small relative to the radius of each cylinder and to the gap width between two neighboring cylinders, but the polarization of the mobile ions in the diffuse layers is allowed. The effect of interactions among individual cylinders is taken into explicit account by employing a unit cell model. The appropriate equations of conservation of electrochemical potential energies of ionic species are solved for each cell, in which a cylinder is envisaged to be surrounded by a coaxial cylindrical shell of the fluid solution. Analytical expressions for the effective electric conductivity are obtained in closed forms as functions of the porosity of the fiber matrix and other characteristics of the porous system. Comparisons of the results of the cell model with different conditions at the outer boundary of the cell are made. Under an otherwise identical condition, the electric conductivity in a porous medium composed of an array of parallel cylinders in the transverse direction is smaller than that of a suspension of spheres. The effect of interactions among the cylinders or spheres on the effective conductivity can be quite significant under appropriate conditions.     

软光刻技术制备液晶显示用定向层

以偶氮聚合物光致表面起伏光栅为模板,制备聚二甲基硅氧烷(PDMS)弹性印章,再以可溶性聚酰亚胺(PI)为“墨水”,在石英玻璃上压印出具有规则起伏结构的PI薄膜.由此制备的PI薄膜显示出很好的使液晶分子定向排列的效果.此方法成本低、效率高,是一种实用的液晶定向层薄膜制备方法.     

The electrochemical interface between copper(111) and aqueous electrolytes

The electrochemical double layer between Cu(111) electrodes and aqueous electrolytes (F⁻ and SO²⁻₄ at various pH values) was studied by means of linear scan voltammetry and ac impedance measurements. It is found that electrochemisorption of oxygen species proceeds on the Cu(111) surface in the potential regions more negative than the electrodissolution potential of copper. The adsorption-desorption kinetics are analysed; the anodic and cathodic symmetry coefficients are found to be equal (α = β = 0.3), and the standard rate constant is k° = 4 × 10⁻¹⁰cm s⁻¹.     

四元交互体系Li+, Mg2+/SO42-, B4O72-—H2O25℃溶解度和溶液物化性质的研究

研究了Li⁺,Mg²+/SO₄^2-,B₄O₇^2-—H₂O四元交互体系25℃时的溶解度和溶液的密度及折光率.四种原始组份未发生脱水作用,体系中也没有复盐或固溶体形成.体系25℃溶解度等温线由五段组成,有四个结晶区,分别对应于四种原始组份,其中以MgB₄O₇·9H₂O的结晶区最大.溶解度等温线上有两个零变量点,其一为MgB₄O₇·9H₂O,MgSO₄·7H₂O,Li₂SO₄·H₂O三盐共饱点,另一为MgB₄O₇·9H₂O,Li₂B₄O₇·3H₂O,Li₂SO₄·H₂O三盐不相称共饱点.     

有机铵盐对FC-SAA表面活性及溶度的影响

测定了一系列有机铵盐与一种全氟烷磺酸盐１：１混合体系水 溶液的表面张力，由此研究有机铵盐对碳氟表面活性剂表面活性及溶度的影响，导出应用于此种混合体系的Ｇｉｂｂｓ吸附公式，并讨论了混合体系中两表面活性组分的表面分子相互作用和表面层的结构。