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

9803851 DeGuire在过去的几年里，文献中已经描述了几种在各种固体衬底上从低温(100℃)的水溶液中沉积陶瓷薄膜的技术。PI的工作重点是在单晶硅和玻璃等衬底上利用有机自组装单分子膜(SAM)作为诱导和控制衬底上氧化膜形成的一种手段。这个GALI项目的目标是详细了解在含和不含自组装膜的衬底上从水溶液中形成薄膜的机理。特别是，在各种技术感兴趣的成膜系统中，将评估固体在衬底上的异相成核与胶体颗粒在衬底上组装的相对重要性。该项目被细分为几个领域：1)从水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x射线散射测量，以监测颗粒的形成和生长随时间的变化；2)研究陶瓷颗粒与衬底表面之间的相互作用，以及这些相互作用对薄膜微结构的影响。DLVO理论将被用来估算陶瓷颗粒与基板之间的作用力。这些计算将与使用原子力显微镜(AFM)直接测量这些力进行比较。原子力显微镜还将用于观察薄膜生长，从其最早的原位阶段，到薄膜表面形貌的非原位观察；3)将这一基本认识与自组装膜的一些独特能力相结合的实验，以优化特定应用的生长速度和/或薄膜微结构。从水溶液中沉积%的薄膜是气相和化学前驱体技术的潜在替代技术。较低的加工温度最大限度地减少了与基片-薄膜互扩散和热膨胀失配相关的问题。然而，从水溶液中加工的材料的微观结构和性能的控制程度没有气相技术那么大。这个项目通过使用SAMS来解决这个问题。这个Goali项目的行业合作者是卡特彼勒技术中心。合作包括人员交流(CWRU在卡特彼勒工作的人员，CWRU在CWRU工作的工业科学家)，对卡特彼勒设备进行的测试，以及担任研究生联合顾问的工业科学家。除了卡特彼勒，德国斯图加特的Max-Planck-Institut毛皮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这个项目。每一次合作都带来了拟议研究不可或缺的设施和专业知识，并提供了各种工作环境，将为参与该项目的学生研究人员扩大研究经验的教育价值。该项目由材料研究部的陶瓷项目和数学和物理科学局的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. ***