CAREER: Structure-Property Relationships of Nanocrystalline Oxide Films for Gas Sensors

可靠的化学传感器的研究和开发与各种燃烧过程对空气污染和燃料燃烧效率的高度控制的需求相平行，以及对涉及易燃和有毒气体的家庭和工业活动中的安全的日益关注。开发灵敏、选择性和耐用的气体传感器的主要障碍之一是缺乏对这些设备操作所涉及的基本过程以及这些过程与传感材料的微观结构和组成之间的关系的充分了解。这一学院早期职业发展项目将专注于纳米晶氧化锡材料，这是一个用作化学传感器的模型系统，以获得对结构-性能关系的基本了解。计划进行系统的实验，以研究：(1)高温下气体环境中反应过程中的微观结构不稳定性和晶体缺陷(如晶体剪切面、晶界和掺杂)的演变；(2)单个缺陷(晶体剪切面、孪晶界和特殊晶界)和界面的原子结构和电子特征；(3)高温下不同气体气氛中微结构、形貌和化学成分信息与电学测量的关系。纳米氧化锡薄膜的研究将利用空间分辨显微镜和光谱技术，并结合在各种模拟气体环境中的阻抗测量来进行。具体地说，这种先进的显微技术将与样品的热和化学前处理相结合，使用一种专门设计的设备来模拟气体传感器在使用中遇到的环境。通过该研究项目的过程，国际晶体物理研究所计划探索用于晶体物理学生教育和培训的商业软件模拟程序。此外，还将建立一个可通过网络访问的虚拟显微镜数据库，以获取图像、晶体结构效果图和演示现场电子显微镜观察的视频剪辑/片段。开发灵敏、选择性和耐用的气体传感器的主要障碍之一是缺乏对这些设备操作所涉及的基本过程以及这些过程与传感材料的微观结构和组成之间的关系的充分了解。该学院早期职业发展项目关于模型气敏材料氧化锡的结构和化学的结果将用于解释该材料的电学性能和传感性能，并将为如何量身定做具有优化的微结构和理想的传感性能的固态化学传感器提供指导。拟议的研究涉及利用和开发一些先进的工具，如图像模拟、结构建模和电子显微镜。该教育计划的长期目标是开发非传统和创新的教学技术，为毕业生提供在现代科学和工程领域蓬勃发展所需的智力、创造性和科学理解。这些方法的目的是确保学生为未来的科学和工业环境做好充分的准备。

9875405PanThe 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.