Ceramic Thin Films From Aqueous Solutions: Studies of the Deposition Mechanism

小行星9803851 在过去的几年中，文献中已经描述了几种用于在低温（100 ℃）下从水溶液在各种固体基底上沉积陶瓷薄膜的技术。 PI的工作集中在有机自组装单分子层（SAMs）的生物启发使用上，如单晶硅和玻璃，作为诱导和控制氧化膜在基底上形成的手段。 这个GOALI项目的目标是获得详细的了解的机制，膜形成从水溶液中，基板上有和没有自组装膜。 特别是，相对于组装的胶体颗粒在基板上的固体上的非均质成核的相对重要性，将评估在各种成膜系统的技术利益。 该项目分为几个方面：1）从水源溶液中形成陶瓷颗粒的热力学和动力学研究。 将采用的研究工具包括溶液过饱和度的热力学计算，结合沉积介质的小角度X射线散射测量，以监测随时间变化的颗粒形成和生长; 2）陶瓷颗粒与基体表面相互作用的研究，以及这些相互作用对薄膜微观结构的影响。 DLVO理论将被用来估计陶瓷颗粒和基板之间的力。 计算结果将与使用原子力显微镜（AFM）直接测量这些力进行比较。 AFM还将用于观察薄膜生长，从原位的最早阶段到薄膜表面形貌的非原位观察; 3）将这种基本理解与SAM的一些独特能力相结合的实验，以优化特定应用的生长速率和/或薄膜微结构。 从水溶液中沉积薄膜是气相和化学前体技术的潜在替代品。 低处理温度使与衬底-膜相互扩散和热膨胀失配相关的问题最小化。 然而，从水溶液加工的材料的微观结构的控制程度以及因此的性能不如从气相技术加工的材料的控制程度大。 本项目通过使用SAMS解决这一问题。 该GOALI项目的工业合作伙伴是卡特彼勒技术中心。 合作包括人员交流（CWRU人员在卡特彼勒工作，工业科学家在CWRU工作），在卡特彼勒设备上进行测试，以及工业科学家担任研究生的联合顾问。 除卡特彼勒外，德国斯图加特的马克斯-普朗克金属研究所和田纳西州橡树岭的橡树岭国家实验室也参与了该项目。 每次合作带来的设施和专业知识是不可或缺的拟议研究，并提供了各种工作环境，将扩大研究经验的教育价值，为学生研究人员参与该项目。 该项目由材料研究部陶瓷计划和数学和物理科学理事会多学科活动办公室共同资助。 ***

9803851 DeGuire In the last several years, several techniques have been described in the literature for depositing ceramic thin films from aqueous solutions at low temperatures (100 C) on various solid substrates. Work by the PI has focused on the bioinspired use of organic self assembled monolayers (SAMs), on substrates such as single-crystal silicon and glass, as a means of inducing and controlling the formation of oxide films on the substrate. The objective of this GOALI project is to obtain a detailed understanding of the mechanism by which films form from aqueous solutions, on substrates with and without SAMs. In particular, the relative importance of heterogeneous nucleation of solid on the substrate, versus assembly of colloidal particles on the substrate, will be assessed in a variety of film-forming systems of technological interest. The project is subdivided into several areas: 1) Studies of the thermodynamics and kinetics of the formation of ceramic particles from the aqueous source solutions. The research tools to be applied include thermodynamic calculations of the degree of supersaturation of the solutions, in combination with small-angle x-ray scattering measurements of the deposition media to monitor the formation and growth of particles as a function of time; 2) Studies of the interactions between ceramic particles and the substrate surfaces, and the influences of those interactions on the films' microstructures. DLVO theory will be used to estimate the forces between ceramic particles and the substrates. The calculations will be compared to direct measurement of these forces using the atomic force microscope (AFM). The AFM will also be used to observe film growth, from its earliest stages in situ, to ex-situ observations of the films' surface topographies; 3) Experiments combining this fundamental understanding with some of the unique capabilities of SAMs to optimize growth rates and/or film microstructures for specific applicatio ns. %%% Thin film deposition from aqueous solution are potential alternatives to vapor-phase and chemical-precursor techniques. The low processing temperature minimize problems related to substrate-film interdiffusion and thermal expansion mismatch. However, the degree of control of the microstructure and thus the properties of the materials processed from aqueous solutions is not as great as from vapor-phase techniques. This project addresses that issue by the use of SAMS. The industrial collaborator in this GOALI project is Caterpillar Technical Center. The collaboration includes personnel exchange (CWRU people working at Caterpillar, the industrial scientist working at CWRU), tests being performed on equipment at Caterpillar, as well as the industrial scientist serving as a co-advisor to the graduate students. In addition to Caterpillar, the Max-Planck-Institut fur Metallforschung in Stuttgart, Germany and Oak Ridge National Laboratory in Oak Ridge, Tennessee are participating in this project. Each collaboration brings facilities and expertise that are integral to the proposed research, and offers a variety of working environments that will expand the educational value of the research experience for the student researchers involved with the project. This project is co-funded by the Ceramics Program of the Division of Materials Research and the Office of Multidisciplinary Activities of the Mathematical and Physical Sciences Directorate. ***