CAREER: Aerosol Droplet Combustion Synthesis of Nonequilibrium Nanoscale Materials

摘要--这是燃烧气溶胶合成制备复杂的纳米陶瓷材料的一项基础性探索。在燃烧气溶胶合成中，陶瓷前驱体溶解或分散在可燃载体中；当该载体雾化成高温火焰时，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能够产生化学复杂的结晶材料，而不需要进一步的热处理。首先要研究的材料是氧化钇稳定的氧化锆，因为它可用作热障、涂层、催化剂和催化剂载体。考虑了一系列的氧化钛成分，以确定这种表面原子浓度较高的纳米材料是否表现出与传统稳定氧化锆相同的相行为转变。讨论的合成问题包括控制反应气溶胶液滴的大小，通过凝聚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气的蒸发和随后的冷凝形成颗粒。关键问题是将纳米粒子的团聚降至最低的能力，以及控制其化学成分的能力。由纳米陶瓷固化而成的先进陶瓷材料有可能提供比大颗粒陶瓷更好的机械、光学和电子性能。潜在的应用包括阻挡层、催化剂、结构材料和超导线芯。教育工作包括利用互动学习开发一门气溶胶科学课程，并与波士顿科学博物馆合作开发一个实践解释模块，将纳米尺度世界作为介于原子和宏观制度之间的领域加以阐述。

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.