Characterization of the diffusion process in oxide glasses based on the correlation between electric conduction and dielectric relaxation

Electric conduction was correlated with dielectric relaxation for many ionically and electronically conducting oxide glasses. On the basis of this correlation, the carrier-diffusion process occurring in the glasses was identified. Of the three types of diffusion processes (localized diffusion process, non-localized diffusion process I and non-localized diffusion process II) one or more were found in each glass. The diffusion process shifted from one type to another with varying glass composition in certain series of glasses. The conditions of preparation of the glasses were found to influence the diffusion processes in these glasses. These facts are discussed in terms of the ‘microstructure’ of glass.     

锰锌铁氧体材料的制备研究新进展

介绍了目前国内外制备锰锌铁氧体材料的主要方法及研究进展,包括传统的干法工艺(陶瓷工艺)和湿法工艺等,同时指出了各种制备方法的优缺点.认为煅烧条件的控制及产品粒径的分布是影响材料磁性能的关键,湿法工艺中的溶胶-凝胶法和水热法是今后研究的主要方向.     

Numerical design of Metal‐Organic Vapour Phase Epitaxy process for gallium nitride epitaxial growth

The paper presents the results of numerical simulations and experimental measurements of the epitaxial growth of gallium nitride in Metal Organic Vapor Phase Epitaxy within a AIX‐200/4RF‐S reactor. The aim was to develop optimal process conditions for obtaining the most homogeneous crystal layer. Since there are many factors influencing the chemical reactions on the crystal growth area such as: temperature, pressure, gas composition or reactor geometry, it is difficult to design an optimal process. In this study various process pressures and hydrogen volumetric flow rates have been considered. Due to the fact that it is not economically viable to test every combination of possible process conditions experimentally, detailed 3D modeling has been used to get an overview of the influence of process parameters. Numerical simulations increased the understanding of the epitaxial process by calculating the heat and mass transfer distribution during the growth of gallium nitride. Appropriate chemical reactions were included in the numerical model which allowed for the calculation of the growth rate of the substrate. The results obtained have been applied to optimize homogeneity of GaN film thickness and its growth rate.     

Fine-patterning on glass substrates by the sol-gel method

A novel process has been developed to form fine patterns on glass substrates. The process consists of the following steps: (1) coating of gel film on a substrate, (2) patterning on the gel film, and (3) heat-treatment. The key point in this process is the control of hardening of the gel films by the addition of organic polymers such as polyethylene glycol (PEG). The addition of PEG increased the viscosity of the coating solutions and delayed the gelation time, but had little effect on the optical properties of the resultant heat-treated glass films. The newly developed process is expected to be applicable to the formation of the optical devices such as diffraction gratings and pre-groovesof optical memory disks.     

应用于生物荧光检测的微流控芯片的研究

主要描述了用SU-8胶制造微流控芯片模具的方法,并在此基础上成功制备微流控芯片.讨论了其制备工艺流程,主要包括有前烘、中烘、光刻、显影等因素对模具的影响,提出了一个可供参考的模具制作工艺流程,并对抗粘层工艺进行了讨论,最终成功制作出模具.研究了用浇铸工艺制作PDMS微流控芯片的方法,利用聚焦的原理,实现粒径12微米左右待检测微球的单通和荧光检测,该芯片同时可以用于其它方面的生物检测.     

沉淀法制备纳米ZrO2粉末过程中团聚体形成与控制的研究

依据沉淀过程的动力学分析,研究了沉淀法制备纳米ZrO2粉末团聚体的形成机理及控制技术.实验结果表明:在沉淀反映过程中,当晶粒聚集形成胶粒的初始聚集过程成为控制过程时,粉末的团聚体形成于沉淀反映过程;当胶粒聚集形成三维网络状更大聚集体的二次聚集过程成为控制过程时,团聚体形成于干燥煅烧过程.沉淀过程中,同时引入合适的胶体保护剂和络合剂可以控制初始和二次聚集过程,从根本上控制了胶粒的聚集特征,因而控制了粉末的团聚状态.     

Kinetic Nature of the Process of Microindentation into Alkali Halide Crystals

The investigation of the dependence of indentor intrusion depth on the time of load application and temperature for the alkali-halide crystals KCl, LiF, NaCl has been carried out. The dependence of indentor intrusion velocity logarithm lg ḣ in microhardness H appears to be linear in the investigated interval of loading times and temperatures. The data obtained may prove the thermofluctuational character of the microindentation process. — The activation energy of microindentation process almost coincides with the activation energies of the sublimation process.     

Synthesis of dense polycrystalline GaN of high purity by the chemical vapor reaction process

A process for producing high-purity, dense polycrystalline gallium nitride is proposed. Dense polycrystalline gallium nitride was produced by the reaction of ammonia, gallium metal, and a halide source in a quartz boat containing metallic gallium. The process is called the chemical vapor reaction process. The hard crust-like pieces of polycrystalline GaN obtained are of high purity, can be used as source material for single-crystal growth by the ammonothermal technique, sublimation, sputtering, and pulse laser deposition.     

NaCl(OH-)色心晶体制备中的固态缺陷化学反应

采用提拉法生长单晶,通过附加金属着色、淬火、室温和液氮温度光聚集等过程,制备了NaCl：(F2^ )H色心激光晶体。研究了NaCl(OH)晶体中色心形成的固态化学反应,结果表明在附加着色过程中发生了热形成、热聚集、热结合和可逆反应,在淬火过程中发生了热分解和可逆反应,在光聚集过程中,发生了光聚集反应、异构化反应和可逆反应。     

N型TOPCon晶硅太阳能电池光注入退火增效的研究

N型隧穿氧化层钝化接触(Tunnel Oxide Passivating Contacts,TOPCon)太阳能电池完成印刷烧结后,再经过光注入,效率有明显提升,主要表现在Voc(开路电压)及FF(填充因子)的提升.其机理在于通过温度和光照强度调节费米能级变化,控制H总量及价态来提高钝化性能.钝化膜层的质量、硅基体掺杂...     

染料敏化太阳电池工艺参数的优化

染料敏化纳晶TiO2薄膜太阳电池的性能受TiO2浆料组成、薄膜厚度、烧结工艺、染料浸渍时间、导电玻璃类型以及电极处理工艺等因素影响是很明显的.通过对上述各工艺参数的研究,探讨了它们对电池性能的影响规律,获得了最佳的工艺参数组合.     

Key experiments in highly viscous liquids

The flow of highly viscous liquids is still a theoretical no-man's-land, with many contradictory theories competing for the explanation of the flow process. On the other hand, a rapid experimental development, in particular in the field of broadband dielectric spectroscopy, supplies more and more information on the nature of the highly viscous flow. The flow process itself (the so-called primary or alpha-process) seems to be intimately related to faster precursor processes, which appear either as part of the wing of the flow process itself or as a secondary relaxation peak, the “Johari-Goldstein” peak, often five orders of magnitude faster than the primary process. An aging experiment shows that the secondary process occurs between strongly asymmetric states, with an energy difference of about 4 k_BT. The paper describes some of these key experiments and their possible theoretical interpretation.     

Berechnung der Übersättigung bei der Kristallisation von InAs aus der Gasphase

It is proved that under experimental conditions for the growing of InAs crystals from the vapour phase the partial supersaturation of indium monoiodide corresponding to the difference of partial pressure of InJ_(g) in the source and in the crystallisation zones, can serve as a quantitative process parameter granting predictions on process development and results in a wide range of ruling conditions. Experiments confirmed the conclusions postulated on the base of quantitative analysis of the transport process. The analysis enables to controll the process parameters of crystal growth by chemical transport.     

基于神经网络和遗传算法的铸锭晶体硅质量控制及工艺优化

铸锭晶体硅是太阳能级晶硅材料的重要来源之一,为了进一步降低硅片成本,需要在保证晶体质量的同时发展大尺寸铸锭晶硅。影响铸造晶体硅质量的热场控制核心参数包括晶体生长速度与生长界面温度梯度之比V/G、壁面热流q、生长界面高度差Δh和硅熔体内部温差ΔT等。针对铸锭晶体硅生长过程中的质量控制问题,本研究基于人工神经网络(ANN)模型对晶体生长过程建立了工艺控制优化方法,利用实验测量数据和数值仿真模拟结果构建铸锭晶体硅生长过程的工艺控制数据集,以底部隔热笼开口和侧、顶加热器功率比作为主要工艺控制参数,V/G、|q|、|Δh|和ΔT为优化目标,建立用于研究晶体生长工艺控制参数和热场参数之间映射关系的神经网络模型。使用训练完成的模型分析底部隔热笼开口及侧、顶加热器功率比对晶体生长过程热场的影响规律,并采用遗传算法(GA)对铸锭晶体硅生长过程的工艺控制参数以提高晶体质量为目标进行优化,最后结合实际生产中的检测图像讨论了V/G对晶体质量的影响。研究表明晶体生长中期的V/G沿横向变化较平缓,对应缺陷较少且分布均匀,因此增大V/G在横向上的均匀度也是提高晶体质量的一个重要因素。     

Chemical processes in glass polishing

Chemical processes which occur during glass polishing are reviewed within the context of current mechanical models for the polishing process. The central chemical process which occurs is the interaction of both the glass surface and the polishing particle with water. A detailed mechanico-chemical model for the polishing process is proposed.     

多孔硅形成机理的逆结晶学模型

本文概述了多孔硅形成机理和现有模型.通过观察和分析多晶多孔硅化学腐蚀机理提出了一个新模型:多孔硅形成机理的逆结晶学模型.这个模型指出多晶多孔硅均匀形貌具有自选择性,而此自选择性受结晶学原理控制.此模型的提出对研究晶体生长有用.     

Influence of decomposition parameters on agglomeration process and total soda content in precipitated Al(OH)3

Grain size composition of precipitated Al(OH)₃ is dependent on the mechanism of decomposition process of the caustic solution which determines crystal growth process, agglomeration process and secondary nucleation. Because the literature data shows that the growth rate is very low, the agglomeration process plays an important role in increasing the initial particle size. On the other hand, the agglomeration process enables the inclusion of impurities by the grain boundary of sticking Al(OH)₃ particles, above all, the inclusion of soda Na₂O.

In this paper we investigate the influence of caustic soda concentration Na₂O_(c), that is the supersaturation of the solution, seed charge and seed grain size on the agglomeration and secondary nucleation processes and total soda content in precipitated Al(OH)₃. The results have shown that the factor which causes the increase of the agglomeration process also causes the increase of total soda content in precipitated Al(OH)₃.     

Investigation of the Crystallization Process in the Verneuil Techniques

The stability of the process of crystallization in the Verneuil techniques is analyzed, taking into account the geometrical shape of the molten layer surface and specific features of the heat and mass transfer typical for this method of crystal growth. The process is stable for crystal radii below the capillarity constant.     

Solid mechanics and material strength studies on the melt growth of bulk single crystals

Microdefects such as dislocations and macrocracking should be controlled during the crystal growth process to obtain high-quality bulk single crystals. Solid mechanics and material strength studies on the single crystals are of importance to solve the problems related to the generation and multiplication of dislocations and the cracking of single crystals. The present paper reviews such research activities that comprise the thermal stress analysis during crystal growth process, the dislocation density estimation during crystal growth process, and the cracking of single crystal due to thermal stress.     

Enhanced Automatic Diameter Control System of Czochralski-grown Crystals

The automatic diameter control system with two ways of the crystal diameter determination is described. The correction of temperature oscillations during the growth process is applied in the describing system. Also, it allows to estimate the crystal quality already during the growth process. The control system is intended for the growth of crystals with different physical properties.