Non-equilibrium Phase Discovery in Finite-sized Systems

非技术总结发现性能更好的新材料是技术进步的驱动力。一个可能有大量此类改进的领域是，在正常条件下不能稳定形成的系统。在这种情况下，“正常条件”和“稳定的”意味着热力学平衡，这是一种科学的方式，说某事不会随着时间的推移而改变，因为它处于热、机械、化学和辐射平衡中。通过避免平衡，可以获得新的材料构型，并且这些新构型可能具有新的和更好的性能。在这个项目中，将通过创建如此小的材料系统来避免平衡，这些材料系统以肉眼看不到的尺寸存在。通过直接从气相中凝聚尺寸为几纳米(1x10^-9m)的固体颗粒，并保持纳米颗粒之间的隔离，通常不结合在一起的元素可以被迫混合，从而对这些材料系统的物理性质产生巨大影响。通过这种方式，可以发现和开发新的磁性材料，对能量转换产生潜在的深远影响，以改进电机、发电机、数据存储，甚至生物医学设备。此外，还将更好地理解材料在非常、非常小的系统中的行为和结构形成。该项目还侧重于培养下一代科学家。该项目将支持一名研究生，在与国际合作伙伴合作的同时，学习先进的材料制造、表征和建模技术。该项目还为社区本科生转读四年制科学或工程(即STEM)学位课程提供支持，目的是为过渡到大学环境提供便利。最后，该项目将与现有的教师研究经验计划合作，为社区大学或高中理科教师及其学生提供纳米技术方面的教育机会。技术总结这个项目将探索非平衡材料领域，通过创建孤立的、有限大小的系统来避免整体平衡。这将通过使用惰性气体冷凝来创建纳米级的纳米颗粒来实现，这些纳米颗粒将彼此分离。围绕通常不相容的体系，有望形成新的固溶体合金和新的有序结构(即金属间化合物)。此外，通过控制纳米颗粒的尺寸，可以探索与尺寸相关的相形成，为温度-组成相图增加了另一个轴。惰性气体冷凝是一种理想的方法，可以在大的组成空间内形成各种纳米材料，并极好地控制它们的尺寸。特别是，在小的纳米颗粒尺寸时，会形成完全或延长的固溶体，对磁性行为有很大的影响。在这里，重点将集中在Fe和Co与4d和5d过渡金属(如W和Mo)合金化，其中广泛的固溶体形成可以对磁性行为产生深远影响，以及铜、银和Au，它们不相容，但可能有形成非平衡金属间化合物的倾向。这些研究将与意大利热那亚大学的研究人员合作进行计算研究。从这个项目中获得的知识将扩大对纳米级合金和结构形成的理解，以及开发用于能量转换系统、数据存储和生物医学应用的新材料。最终，这个项目提供了一条探索被整体平衡隐藏的未被发现的结构的世界的途径。该项目还为一名研究生和一名社区本科生转读四年制科学或工程(即STEM)学位课程提供支持，目的是为过渡到大学提供便利。最后，该项目将与现有的教师研究经验计划合作，为社区大学或高中科学教师以及随后的学生提供纳米技术教育机会。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYThe discovery of new materials with improved properties is a driver for technological advancement. An area potentially abundant with such improvements are systems that under normal conditions, cannot be formed stably. In this context, "normal conditions” and “stably” mean thermodynamic equilibrium, which is a scientific way of saying something will not change over time because it is in thermal, mechanical, chemical and radiative balance. By avoiding equilibrium, new configurations of materials can be accessed, and these new configurations may having new and better properties. In this project, equilibrium will be avoided by creating systems of material that are so small, they exist at a size invisible to the human eye. By condensing solid particles directly from a gas phase, with dimensions of a few nanometers, (1 x 10^-9 m) and maintaining isolation between the nanoparticles, elements which normally don’t go together, can be forced into mixing, thereby producing dramatic effects on the physical properties of these material systems. In this way, new magnetic materials can be discovered and developed, with potentially profound impacts on energy conversion to improve motors, generators, data storage, and even biomedical devices. Furthermore, a better understanding of materials behavior and structure formation in very, very small systems will result. This project is also focused on training the next generation of scientist. This project will support a graduate student who will learn advanced materials fabrication, characterization, and modeling techniques, while working with international partners. The project also provides support for an undergraduate community college student transferring to a four-year science or engineering (i.e., STEM) degree program, with the goal to ease the transition to the university environment. Finally, this project will partner with an existing Research Experience for Teachers Program, providing educational opportunities in nanotechnology for community college or high school science teachers as well as their students. TECHNICAL SUMMARYThis project will explore the field of non-equilibrium materials, by avoiding bulk equilibrium by creating isolated, finite-sized systems. This will be accomplished by using inert gas condensation to create nanoparticles on the order of nanometers, which will be isolated from one another. Focusing on normally immiscible systems, novel solid solution alloys and new ordered structures (i.e., intermetallic compounds) are expected to form. In addition, by controlling the size of the nanoparticles, the size-dependent phase formation can be explored, adding another axis to the temperature-composition phase diagram. Inert gas condensation is an ideal method of forming a wide variety of nanomaterials over large composition space, with excellent control over their size. In particular, at small nanoparticle sizes, complete or extended solid solution formation occurs, with strong effects on the magnetic behavior. Here, the focus will be on Fe and Co alloyed with 4d and 5d transition metals such as W and Mo, where extensive solid solution formation can have profound effects on the magnetic behavior, as well as Cu, Ag, and Au, with which they are immiscible but may have the propensity to form non-equilibrium intermetallic compounds. These investigations will be done in collaboration with computational studies by researchers at the University of Genoa, Italy. The knowledge gained from this project will expand the understanding of alloy and structure formation at the nanoscale, as well as develop new materials for energy conversion systems, data storage, and biomedical applications. Ultimately, this project provides a pathway to explore a world of undiscovered structures hidden by bulk equilibria. The project also provides support for a graduate student and an undergraduate community college student transferring to a four-year science or engineering (i.e., STEM) degree program, with the goal to ease the transition to the university. Finally, this project will partner with an existing Research Experience for Teacher program, providing nanotechnology educational opportunities for community college or high school science teachers and subsequently their students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.