激光实时全息干涉法测量甘氨酸水溶液扩散系数

本文利用激光实时全息干涉技术 ,测量了甘氨酸水溶液的扩散系数。首先测定了 2 98.15K下蔗糖水溶液的扩散系数 ,取得了较好的结果 (总相对误差为 0 .84 % ) ,证明了装置的准确性。进而用该装置对不同浓度下的甘氨酸水溶液进行测定 ,得到了不同浓度甘氨酸水溶液在不同位置的扩散系数及每一浓度下的平均扩散系数 ,并对结果进行了分析和讨论     

激光全息干涉法测量维生素B6的扩散系数

为了研究维生素B6的扩散行为,采用了激光全息干涉法,得到了298.15K时不同浓度维生素B6在水溶液和生理盐水中的扩散系数。结果表明,维生素B6在水溶液中的扩散系数随着溶质浓度的增大一直下降,而在生理盐水中则呈现先上升后下降的趋势。这对维生素B6的医学应用具有重要的参考价值。     

L-抗坏血酸水溶液扩散系数的全息干涉法测量

设计并建立了一套用于液相扩散系数测定的激光实时全息干涉及液相扩散模拟系统。测定了25℃0.33mol/LKCl水溶液的扩散系数,结果与文献值非常接近,证明了仪器的准确性。进而利用该装置测定了不同浓度(0.0100、0.0287、0.0542、0.0822、0.1007mol/L)的L 抗坏血酸水溶液的扩散系数,得到了不同浓度L 抗坏血酸水溶液在不同位置的扩散系数以及每一浓度的平均扩散系数为13.5552、12.5230、11.4577、10.5606、10.0148×10-6cm2/s。     

锌在磷化铟单晶中扩散行为的研究

本文采用 Zn_3P_2作扩散源进行真空闭管扩散,对锌在 InP 单晶中的扩散行为作了研究。通过实验给出了扩散系数与温度的关系,并得到了锌在InP 单晶中的激活能。通过实验发现:在相同扩散温度下表面受主浓度随结深加大而减少。采用空位随时间变化的模型解释了这一实验结果,研究了高阻衬底片 p-n 结显示时出现双线的问题。     

微波辐射下L-丙氨酸消旋反应研究与优化

微波辐射下的L-丙氨酸消旋反应是一种新的工业化生产方法,具有环保的优点。本文应用单因素轮换试验法考察了反应的影响因素,而后通过响应面分析法对各影响因素进行优化,确定了在微波辐射下,以560W的微波输出功率,用1.2mol/L氢氧化钠水溶液替代乙酸作为反应溶剂,用0.14摩尔比的水杨醛为催化剂,L-丙氨酸可以快速消旋。得出消旋反应随微波辐射功率的提高而加快。同时也讨论了微波作用下L-丙氨酸的消旋反应机理。     

质子在a-SiO2中的扩散机制

半导体电子器件中质子的扩散会导致器件性能下降。然而，迄今为止关于质子在氧化物中的扩散机制目前尚未完全清楚。本文从原子层面研究了质子在a-SiO2中的扩散行为。采用从头计算分子动力学模拟方法，计算得到了质子在a-SiO2中的扩散系数和活化能。同时，观察到了质子扩散路径。研究发现，质子主要是通过与a-SiO2中的氧原子形成和解离化合键的形式进行扩散。本文提出了质子在a-SiO2中扩散的2种方式：跳跃扩散和旋转扩散，并分别计算了这2种扩散方式所需要的势垒。     

一种改进的各向异性扩散超声图像去噪算法

针对传统的各向异性扩散算法中扩散系数函数的平滑效果不好,扩散过程中扩散门限K的选取依靠经验确定,扩散过程对图像细节保护不足的问题,提出了一种改进的各向异性扩散算法。介绍了几种当前比较典型的各向异性扩散去噪算法;在典型算法分析的基础上提出了一种基于自适应中值滤波的改进扩散模型;根据扩散系数应满足的3个条件及经典的扩散系数函数,提出了改进的扩散模型中的改进扩散系数函数;提出了一种扩散门限K的自适应选取的方法。通过在改进的扩散模型中使用改进的扩散系数函数并结合扩散门限K的自适应选取,对超声图像进行去噪。实验结果表明,所提算法优于PM模型、Catte模型、王常虹算法等,去噪后图像的FOM值比PM模型高出3.34%,PSNR值比PM模型高出0.250 6。该算法在去除散斑噪声的同时有效保护了图像的细节及边缘,有助于医务人员对患病区域的准确诊断。     

温度梯度下磷在硅中的扩散

在单晶硅本身存在温度梯度条件下，实验观察到施主杂质磷在硅中的扩散系数比在恒温扩散炉条件下的扩散系数大得多。文中对这种异常扩散现象进行了讨论。     

扩展电阻分析对砷在硅中本征扩散系数的研究

本文扼要叙述了扩展电阻分析用以测量较低浓度砷的剖面的有效性,进而研究了较低浓度砷在硅中的扩散问题.由于通过快速热退火对样品进行预处理,排除了辐照损伤对扩散系数测定的影响,从而测得砷在硅中本来意义下,即替位扩散意义下的本征扩散系数.如所预期,这组数据比国外直至目前所测得的数据要低.浓度剖面的实验数据由非线性扩散方程的数值解进行拟合.结果表明:SUPREM III所采用的模型在较高浓度区扩散系数随浓度递增速率较小,Hu理论仍然和本实验(?)较符合.本文还求得了扣除辐照损伤增强扩散效应后,砷在硅中的激活能为4.42eV     

有色噪声的扩散过程模型

研究使用基于随机微分方程的扩散过程模型产生有色噪声.首先给出Markov扩散过程的平稳分布,该分布给出了扩散过程模型中的漂移系数、扩散系数和有色噪声概率密度分布之间的关系;选择扩散过程模型中的扩散系数为x的一次幂,其系数决定了所生成噪声的相关特性;数值算法使用Milstein高阶法.以三元独立积构造的G-分布雷达杂波为例进行仿真分析,验证所提出方法的准确性和有效性.     

Defect Modulation in Cobalt Manganese Oxide Sheets for Stable and High-Energy Aqueous Aluminum-Ion Batteries

Rechargeable aqueous Al-ion batteries (AIBs) are promising low-cost, safe, and high energy density systems for large-scale energy storage. However, the strong electrostatic interaction between the Al³⁺ and the host material, usually leads to sluggish Al³⁺ diffusion kinetics and severe structure collapse of the cathode material. Consequently, aqueous AIBs currently suffer from low energy density as well as inferior rate capability and cycling stability. Here, defective cobalt manganese oxide nanosheets are reported as cathode material for aqueous AIBs to improve both reaction kinetics and stability, delivering a record high energy density of 685 Wh kg⁻¹ (based on the masses of the cathode and anode) and a reversible capacity of 585 mAh g⁻¹ at 100 mA g⁻¹ with a retention of 78% after 300 cycles. The impressive energy density and cycling stability are due to a synergistic effect between the substituted cobalt atoms and the manganese vacancies, which improve the structural stability and promote both electron conductivity and ion diffusion. When applied in aqueous Zn-ion batteries, a high specific energy of 390 Wh kg⁻¹ at 100 mA g⁻¹ is realized while retaining 84% initial capacity over 1000 cycles. The study offers a new pathway to building next-generation high-energy aqueous rechargeable metal batteries.     

Crystallization of Vaterite Nanowires by the Cooperative Interaction of Tailor‐Made Nucleation Surfaces and Polyelectrolytes

The concepts of template‐induced crystallization on self‐assembled monolayers (SAMs) and the use of polymer additives are combined into a new strategy, where, through the cooperative interaction of a SAM matrix involved in the nucleation process, poly(acrylic acid), a dissolved polyelectrolyte, and the dissolved ions, hierarchically ordered mineral structures are formed. The adsorption of poly(acrylic acid) to the SAM is monitored using a quartz microbalance. Transmission electron microscopy measurements on samples that are taken from polyacrylate solution in short intervals after the start of the reaction reveals that nanometer‐sized particles pre‐formed in solution are being attached to the polymer template. These CaCO₃ nanoparticles are still amorphous 20 min after the start of the mineralization process; the transformation from the amorphous to the crystalline phase takes place within the first 60 min of the reaction. The morphologies of the crystalline products exhibit characteristic differences from those that are obtained in crystallization experiments on self‐assembled monolayers without the polyelectrolyte. This model of cooperative formation of vaterite nanowires represents an alternative to current models of structure formation, where two‐phase systems (e.g., microemulsions or foams) act as a structure‐directing interface, or the mineralization process is caused by the diffusion of a hydrolyzable component from a non‐aqueous into an aqueous phase.     

Manufacturing of solder bumps with Cu/Ta/Cu as under bumpmetallurgy

This study investigated the feasibility of the multilayer Cu/Ta/Cu under bump metallurgy (UBM), deposited on AlN/Si where AlN is a thin film. An interdiffusion study found that Ta is an appropriate diffusion barrier layer for the investigated solder bump structure. The temperature profiles and the flux compositions for solder reflow were also investigated. The flux activators investigated include succinic acid, adipic acid, stearic acid, dimethylamine hydrochloride, and diethylamine hydrochloride. Among these, succinic acid was the most appropriate in terms of wetting and cleaning     

The Measurement of Ion Diffusion in Epoxy Molding Compounds by Dynamic Secondary Ion Mass Spectroscopy

The primary focus of this research was the measurement of ion diffusion in a common epoxy molding compound used to encapsulate microelectronic devices. Ion diffusion measurements were made by exposing the encapsulant materials to aqueous solutions of 2M sodium chloride, and making measurements by Dynamic Secondary Ion Mass Spectrometry. The diffusion dependency of temperature exposure of the encapsulants to aqueous salt solutions at 75 $^{circ}$C, 85 $^{circ}$C, 100 $^{circ}$C, 125 $^{circ}$C, 150 $^{circ}$C and 175 $^{circ}$C and post-mold curing for 2, 4, 6, and 8 h at 175 $^{circ}$C was evaluated. The ion diffusion was found to depend on the glass transition temperature of the encapsulant. The rate of ion diffusion above the glass transition temperature of the encapsulant was faster than predicted by an Arrhenius plot of the diffusion coefficient as a function of temperature below the glass transition temperature. Post-mold curing of the encapsulant decreased the diffusion of chloride ions in the encapsulant. Ion diffusion was shown to be slower than moisture diffusion in the encapsulant by approximately nine orders of magnitude.      

Nanoporous Alumina Membranes as Diffusion Controlling Systems

This work describes the use of nanoporous alumina membranes for the diffusion of crystal violet molecules, encapsulated in the micelles of sodium dodecylsulfate (SDS), through pores ranging between 20 and 200 nm in diameter. The encapsulation of the crystal violet in SDS micelles is necessary in order to enlarge the size of the molecules to such an extent that the pore size becomes a speed‐controlling function. Superior results were obtained when the membrane‐containing capsule is placed into a water‐filled beaker, and carefully moved by means of a “tipping bridge” in order to prevent diffusion problems in the capsule. Free crystal violet was liberated following diffusion due to the low SDS concentration in the aqueous solution, which was far below the critical micelle concentration (CMC). Micelle formation and encapsulation of crystal violet is shown by UV‐visible and fluorescence spectroscopies. The experiments described herein serve as an exploratory test for developing novel drug delivery systems.     

High-Power and Ultrastable Aqueous Calcium-Ion Batteries Enabled by Small Organic Molecular Crystal Anodes

Calcium ion batteries (CIBs) are pursued as potentially low-cost and safe alternatives to current Li-ion batteries due to the high abundance of calcium element. However, the large and divalent nature of Ca²⁺ leads to strong interaction with intercalation hosts, sluggish ion diffusion kinetics and low power output. Herein, a small molecular organic anode is reported, tetracarboxylic diimide (PTCDI), involving carbonyl enolization (CO↔C O⁻) in aqueous electrolytes, which bypasses the diffusion difficulties in intercalation-type electrodes and avoid capacity sacrifice for polymer organic electrodes, thus manifesting rapid and high Ca storage capacities. In an aqueous Ca-ion cell, the PTCDI presents a reversible capacity of 112 mAh g⁻¹, a high-capacity retention of 80% after 1000 cycles and a high-power capability at 5 A g⁻¹, which rival the state-of-the-art anode materials in CIBs. Experiments and simulations reveal that Ca ions are diffusing along the a axis tunnel to enolize carbonyl groups without being entrapped in the aromatic carbon layers. The feasibility of PTCDI anodes in practical CIBs is demonstrated by coupling with cost-effective Prussian blue analogous cathodes and CaCl₂ aqueous electrolyte. The appreciable Ca storage performance of small molecular crystals will spur the development of green organic CIBs.     

Anomalous acid diffusion in a triphenylene molecular resist with melamine crosslinker

Next generation lithography will require next generation resists. Molecular resists, based on small non-polymeric molecules, promise improvements in line width roughness and resolution control for high resolution lithographic patterns. However, these materials are generally not sensitive enough for commercial application. We have investigated the application of a common chemical amplification scheme to molecular resists. The triphenylene derivative C5/C0 (symmetrical 2,6,11-trihydroxy-3,7,11-tris(pentyloxy)triphenylene), mixed with the crosslinker hexamethoxymethyl melamine and the photoacid generator triphenylsulfonium triflate shows a substantial sensitivity enhancement, requiring a dose of only 5 μC/cm² compared with the pure triphenylene sensitivity of 6500 μC/cm² at 20 keV. Previous work has indicated that the acid diffusion length of the photoacid generator used here is around 350 nm and that the diffusion length decreases with film thickness. However, in this molecular resist system anomalous levels of acid diffusion were observed, indicating that previous results for polymeric systems may not hold true for these new materials. Initial results indicate that the acid diffusion length in this system may be on the order of microns. Furthermore, there is some evidence that the excessive diffusion is occurring in the surface layers of the resist or at the air: resist interface itself.     

An Aqueous Mg2+-Based Dual-Ion Battery with High Power Density

Rechargeable Mg batteries promise low-cost, safe, and high-energy alternatives to Li-ion batteries. However, the high polarization strength of Mg²⁺ leads to its strong interaction with electrode materials and electrolyte molecules, resulting in sluggish Mg²⁺ dissociation and diffusion as well as insufficient power density and cycling stability. Here an aqueous Mg²⁺-based dual-ion battery is reported to bypass the penalties of slow dissociation and solid-state diffusion. This battery chemistry utilizes fast redox reactions on the polymer electrodes, i.e., anion (de)doping on the polyaniline (PANI) cathode and (de)enolization upon incorporating Mg²⁺ on the polyimide anode. The kinetically favored and stable electrodes depend on designing a saturated aqueous electrolyte of 4.5 m Mg(NO₃)₂. The concentrated electrolyte suppresses the irreversible deprotonation reaction of the PANI cathode to enable excellent stability (a lifespan of over 10 000 cycles) and rate performance (33% capacity retention at 500 C) and avoids the anodic parasitic reaction of nitrate reduction to deliver the stable polyimide anode (86.2% capacity retention after 6000 cycles). The resultant full Mg²⁺-based dual-ion battery shows a high specific power of 10 826 W kg⁻¹, competitive with electrochemical supercapacitors. The electrolyte and electrode chemistries elucidated in this study provide an alternative approach to developing better-performing Mg-based batteries.