CAREER: Aerosol Droplet Combustion Synthesis of Nonequilibrium Nanoscale Materials

这是燃烧气溶胶合成生成化学复杂的纳米级陶瓷材料的基础探索。在燃烧气溶胶合成中，陶瓷前体溶解或分散在可燃载体中；当这种载体被雾化到高温火焰中时，每个液滴都可以成为纳米级陶瓷颗粒合成的“微反应器”。高温、放热的液滴燃烧反应可以生成化学复杂的结晶材料，而无需进一步热处理。首先要检查的材料是氧化钇稳定氧化锆，因为它适用于热障、涂层、催化剂和催化剂载体。考虑了一系列氧化钇成分，以确定纳米级材料是否具有高浓度的表面原子，表现出与传统稳定氧化锆相同的相转变行为。研究的合成问题包括控制反应气溶胶液滴的大小，通过冷凝相反应和反应液滴内的成核形成颗粒，以及通过陶瓷化合物蒸汽的汽化和随后的冷凝形成颗粒。关键问题是最小化纳米级颗粒团聚的能力和控制其化学成分的能力。由纳米级陶瓷固化而成的先进陶瓷材料有潜力提供比大粒度陶瓷更好的机械、光学和电子性能。潜在的应用包括屏障涂层、催化剂、结构材料和超导线芯。教育方面的努力包括开发一门使用互动学习的气溶胶科学课程，并与波士顿科学博物馆合作，开发一个动手解释模块，将纳米世界作为原子和宏观制度之间的领域。

Abstract - Helble This is a fundamental exploration of combustion aerosol synthesis to generate chemically complex nanoscale ceramic materials. In combustion aerosol synthesis, ceramic precursors are dissolved or dispersed in a combustible carrier; when this carrier is atomized into a high-temperature flame, each droplet can become a "microreactor" for nanoscale ceramic particle synthesis. The high temperature, exothermic droplet combustion reactions enable the generation of chemically complex, crystalline materials without need for further heat treatment. The first material to be examined is yttria-stabilized zirconia because of its applicability as a thermal barrier, coating, catalyst, and catalyst support. A range of yttria compositions is considered to determine whether the nanoscale material, with its high concentration of surface atoms, shows the same transitions in phase behavior as does conventional stabilized zirconia. Synthesis issues explored include the control of reacting aerosol droplet size, particle formation through the condensed-phase reaction and nucleation within the reacting droplet, and particle formation through the vaporization and subsequent condensation of ceramic compound vapors. Key issues are the ability to minimize agglomeration of nanoscale particles and the ability to control their chemical composition. Advanced ceramic materials consolidated from nanometer-scale ceramics have the potential to provide improved mechanical, optical, and electronic behavior over their larger-grained counterparts. Potential applications include barrier coatings, catalysts, structural materials, and cores of superconducting wires. Educational efforts include development of an aerosol science course using interactive learning and, in conjunction with the Boston Museum of Science, development of a hands-on interpretive module addressing the nanoscale world as a realm between atomic and macroscopic regimes.