Chemical analysis of acidic silicon etch solutions: I. Titrimetric determination of HNO3, HF, and H2SiF6

The chemical etching of silicon using HF-HNO₃ mixtures is a widely used process in the processing of silicon wafers for microelectronic or photovoltaic applications. The control of the etch bath composition is the necessary condition for an effective bath utilization, for the replenishment of the consumed acids, and to maintain a certain etch rate. The present paper describes two methods for the total analysis of the individual etch bath constituents HF, HNO₃, and H₂SiF₆. Both methods start with an aqueous acid-base titration determining the total acid concentration and the concentration of H₂SiF₆. The first method is an acid-base titration using a 0.1 mol L⁻¹ methanolic solution of cyclohexylamine (CHA) as non-aqueous titrant to determine the content of nitric acid. Then, the amount of hydrofluoric acid is calculated from the difference between the total acid and nitric acid content. The second method is based on the determination of the total fluoride concentration using a fluoride ion-selective electrode (F-ISE). The content of hydrofluoric acid is obtained from the difference between the total fluoride content and the amount of fluoride bound as H₂SiF₆. The amount of nitric acid results finally calculated as difference to the total acid content.     

Adsorption of poly(ethylene glycol)s on mercury/aqueous solution interface 1. Kinetics of PEG 8000 adsorption

In order to study the influence of the adsorption of fulvic compounds on voltammetric signals and to understand better the adsorption of these compounds on hydrophobic natural water interfaces, adsorption studies of macromolecules such as poly(ethylene glycol) (HO(CH₂CH₂O)_n) with molecular weight of 8000 were done on the mercury/water interface by a.c. voltammetry at the potential of zero charge. The maximum surface concentration, adsorption equilibrium constant and adsorption rate constant have been determined from the global adsorption mechanism, controlled by two determining steps: diffusion and kinetics of adsorption at the interface.     

过氧化物模拟酶在介体型生物传感器方面应用初探

meso-四(4-磺基苯)卟啉锰(Ⅲ)作为过氧化物模拟酶可催化H_2O_2与K_4Fe(CN)_6反应。电流响应与H_2O_2浓度在3.0×10~(-4)～1.0×10~(-3)mol/L范围内呈线性关系。重现性和回收率良好。抗坏血酸和DL-半胱氨酸干扰严重。     

长余辉发光玻璃SrAl2O4∶Dy, Eu的制备与发光性能研究

在低熔点破璃中掺杂一定量的长余辉发光粉制备了性能优良的长余辉发光玻璃。在保证发光玻璃均匀透明的基础上，发光性能随发光粉掺杂量的增加而增强，尽量降低假烧温度和减少保温时间可以保持良好的发光性能，在还原气氛制备的发光玻璃性能优于在空气中制备的。煅烧工艺对发光玻璃的微观结构有显著的影响。     

Mg-Nd-Zr-Zn合金的制备及钕对合金组织性能的影响

在RJ-2溶剂和Be的联合保护下制备了Mg-Nd-Zr-Zn系合金. 通过对合金组织的分析, 以及Nd对组织性能影响的研究, 试制出了Nd添加量合理的Mg-Nd-Zr-Zn合金. 经过测试, 认为Nd添加量的增加提高了合金的250 ℃高温抗拉强度, 当Nd添加量超过2.8%时, 合金的高温强化作用不十分显著. Mg-Nd-Zr-Zn合金在250 ℃时的拉伸断裂方式主要是韧性断裂.     

AB5型球形合金粉的表面处理研究

由雾化（Gas－atomization）技术制备的AB5型球形合金粉，作为镍氢电池负极材料具有很多优点：粉粒呈球状便于在多孔基片内装填；耐压耐磨性好；抗碱能力强且不易解胶．但它的电化学初活性差，难于活化．有碍电池中的应用．采用适宜的氧化剂（铜盐水溶液）处理，使球粒表面形成一个富铜、富镍亚层，显著地改善了合金粉的电化学活性．经处理的MlNi3.8CO0.5Mn0.3Al0.4球形合金粉，仅3次充放电循环其放电量便可达到240mA·h·g-1；而未经处理的同一合金粉即便经6次充放电循环其放电量也只有103mA·h·g-1．     

裸玻碳电极伏安测定甲氰咪胍

提出了裸ＧＣＥ不需任何处理测定甲氰咪胍的方法，浓度在３×１０＾－７－６×１０＾－５ｇ／ｍＬ，范围内与峰电流呈线性关系，ＲＳＤ为２．２％，回收率为９６％－１０２％。该方法操作简便快速，大多数金属离子和多种有机生化物质不干扰测定，方法用于片剂和加标尿样中甲氰咪胍的测定与药典方法对照，获得满意结果，并对电极反应进行了初步探讨。     

冠醚型电极对局部麻醉药响应功能的研究

用二苯并24-冠-8作为活性物质、邻苯二甲酸二(2-乙基)己酯为增塑剂制得PVC膜电极。电极对局麻药丁卡因、普鲁卡因和利多卡因具有能斯特响应,用于局麻药针剂的测定取得满意的结果。     

蒙脱石修饰碳糊电极测定氨基酸的研究：Ⅱ.酪氨酸的测定

本文报道蒙脱石修饰碳糊电极测定酪氨酸，在０．００１ｍｏｌ／Ｌ ＫＣｌ－ＨＣｌ（ｐＨ＝２．０）溶液中开路富集，介质交换后微分脉冲阳极溶出伏安法测定，在０．５－２．５μｇ／ｍｌ范围内有线性，检测限为６３ｎｇ／ｍｌ。可避免其他氨基酸，微量元素和常量金属元素的干扰，直接用于氨基酸药物样品的分析，获得了满意的结果，还对酪氨酸在电极上的反应机理进行了探讨。