The research and development of reliable chemical sensors parallels the demand for a high degree of control over air pollution and fuel combustion efficiency for a variety of combustion processes, and increasing concern over safety in homes and in industrial activities involving flammable and poisonous gases. One of the main obstacles in the development of sensitive, selective and durable gas sensors has been the lack of adequate understanding of the fundamental processes involved in the operation of these devices and the relationships between these processes and the microstructure and composition of the sensing materials. This Faculty Early CAREER Development project will focus on nanocrystalline tin oxide materials, a model system for use as chemical sensors, to obtain fundamental understanding of the structure-property relationships. Systematic experiments are planned to investigate: (1) microstructural instabilities and crystal defect (e.g., crystallographic shear planes, grain boundaries, and dopants) evolution during the reaction process in the gaseous environment at elevated temperatures; (2) the atomic structure and electronic characteristics of individual defects (crystallographic shear planes, twin boundaries, and special grain boundaries) and interfaces; (3) correlation of microstructure, morphology, and chemical composition information with electrical measurements in different gaseous atmospheres at elevated temperatures. The studies on nanocrystalline tin oxide films will be conducted by spatially resolved microscopy and spectroscopy techniques in combination with impedance measurements within various simulated gaseous environments. Specifically, such advanced microscopy techniques will be combined with the thermal and chemical pre-treatment of specimens using a specially designed apparatus which simulates the environment the gas sensors encounter in use. Through the course of the research project the PI plans to explore the commercial software simulation programs for use in students education and training in crystal physics. In addition, a virtual microscopy database will be established, accessible via the Web, for images, renderings of crystal structures, and video clips/segments demonstrating the in-situ electron microscope observations.
One of the main obstacles in the development of sensitive, selective and durable gas sensors has been the lack of adequate understanding of the fundamental processes involved in the operation of these devices and the relationships between these processes and the microstructure and composition of the sensing materials. The results from this Faculty Early CAREER Development project about the structure and chemistry of tin oxide, a model gas sensing material, will be used to interpret the electrical properties and sensing performance of that material and will provide guidance on how to tailor solid state chemical sensors, which have optimized microstructure and desirable sensing properties. The proposed research involves the utilization and development of a number of advanced tools, such as image simulations, structural modeling, and electron microscopy. The long-term goal of the educational plan is to develop non-traditional and innovative pedagogical techniques that will provide graduates with the intellectual, creative, and scientific understanding needed to prosper in the modern scientific and engineering fields. These approaches are aimed to ensure that the students are adequately prepared for the scientific and industrial environment of the future.
