CAREER: Material Design and Research Oriented Multidisciplinary Education: Amorphous to Nanocrystalline Electronic Materials with Applications to Thermoelectrics

基于非晶的材料可以具有与相同材料的晶体或纳米晶形式根本不同的电学和热学性质。尽管非晶材料已经找到了应用，并继续为现代技术带来希望，但这些材料中的电荷载流子和声子传输仍然是一个争议点。非晶材料中缺乏长程有序和短程有序，导致结构和能量输运之间复杂的相互作用。在该项目中，将开发基于非晶-结晶纳米复合材料形式的大块非晶结构的新型电子材料，并定制其热和电性能。该应用将集中在热电材料上，但其结果有望产生适用于其他功能材料的新科学，包括光学和磁性材料。与研究工作并行的是，将实施一项教育计划，该计划将在高年级本科课程中纳入和开发一项新的教学计划，让本科生参与研究，促进学生的国际合作研究，向公众展示能源材料领域，并为先进的热电材料研究提供资源网站。俄克拉荷马州路易斯·斯托克斯少数民族参与联盟的可用资源（OK-LSAMP）和多元文化工程计划（MEP）计划将用于扩大少数民族学生的参与和高中生的招聘。该研究计划解决了对非晶基材料中电荷和声子输运的物理描述的基本需求，表征其结构依赖性，以及将这种理解应用于增强无定形和更复杂结构的无定形-结晶纳米复合材料的热电性能。重点将特别是在政权的载流子能量保持在非平衡状态，由于连续通过材料域具有不同的平衡能量分布的载流子。将讨论无序多组分非晶-结晶纳米复合材料结构中扩展态和局域态电荷载流子的多模输运。这是一个新的科学问题，有许多尚未解决的科学问题。对这种非晶基材料中载流子和声子输运的进一步理解将直接影响其材料设计，并为电子应用提供新的材料结构。与理论研究平行，将开发一种有效的和可扩展的自上而下的方法来合成这种结构。该材料在单横模微波腔中进行处理，这提供了一种非凡的途径，以相当快速和方便的方式创造出新的非晶材料状态。去结晶过程仅仅通过使固体材料在腔中经受强E或H场而发生。该方法导致原位形成这样的结构，这是不可能通过传统的整体处理方法。这种独特的能力为工程非平衡结构开辟了新的前景。

Amorphous based materials can possess fundamentally different electrical and thermal properties than crystalline or nanocrystalline forms of the same material. Although, amorphous materials have found applications and continue to show promise for modern technologies, charge carrier and phonon transport in these materials remain a point of dispute. The lack of long- and short-range order in amorphous materials leads to complicated interplay between structure and energy transport. In this project a novel class of electronic materials based on bulk amorphous structures in the form of amorphous-crystalline nanocomposites will be developed and their thermal and electrical properties will be tailored. The application will be focused on thermoelectric materials, but the results are expected to produce new science applicable to other functional materials including optical and magnetic materials. Parallel to the research endeavors, an educational plan will be implemented which incorporates and develops a new teaching initiative in the upper-division undergraduate curriculum, involves undergraduates in research, promotes student international collaborative research, exposes the field of energy materials to the general public, and provides a resource web-site for advanced thermoelectric material studies. The available resources in the Oklahoma Louis Stokes Alliance for Minority Participation (OK-LSAMP) and Multicultural Engineering Program (MEP) programs will be used for expanding the participation of minority students and the recruitment of high school students.This research plan addresses the essential need for a physical description of charge and phonon transport in amorphous based materials, characterization of their structural dependencies, and application of this understanding to enhance the thermoelectric performance of amorphous and the more complex structure of amorphous-crystalline nanocomposite materials. The focus will be especially in the regime where the carriers energy remains at non-equilibrium state due to the consecutive passage through material domains with different equilibrium energy distribution of carriers. The multi-mode transport of charge carriers in extended and localized states in disordered multi component amorphous-crystalline nanocomposite structures will be addressed. This is a new scientific problem with many unresolved scientific questions. Further understanding of charge carrier and phonon transport in such amorphous based materials will directly impact their material design and offer novel material structures for electronic applications. Parallel to theoretical studies, an efficient and scalable top-down approach for synthesizing such structures will be developed. The material is processed in a single transversal mode microwave cavity that provides an extraordinary route to create a new state of amorphous materials in a rather quick and convenient way. The decrystallization process happens by merely subjecting the solid material to a strong E or H field in the cavity. The method results in in-situ formation of such structures, which is not possible by conventional bulk processing methods. This unique capability opens a new landscape for engineering non-equilibrium structures.