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

非晶基材料可以具有与晶体或纳米晶体形式的相同材料根本不同的电学和热性能。尽管非晶材料已经找到了应用，并继续显示出现代技术的前景，但这些材料中的电荷载流子和声子输运仍然是一个争议点。由于非晶材料缺乏长程和短程有序，导致其结构与能量输运之间的相互作用十分复杂。在这个项目中，一种基于非晶纳米复合材料形式的非晶体结构的新型电子材料将被开发出来，它们的热学和电学性能将被定制。虽然主要应用于热电材料，但也有望在光学材料、磁性材料等其他功能材料上产生新的科学成果。在研究工作的同时，将实施一项教育计划，在高年级本科课程中纳入并发展新的教学倡议，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，并提供先进热电材料研究的资源网站。俄克拉何马州路易斯·斯托克斯少数民族参与联盟（OK-LSAMP）和多元文化工程项目（MEP）的现有资源将用于扩大少数民族学生的参与和高中学生的招募。本研究计划解决了非晶基材料中电荷和声子输运的物理描述，它们的结构依赖关系的表征，以及应用这种理解来提高非晶和更复杂结构的非晶纳米复合材料的热电性能的基本需求。特别关注由于载流子连续通过具有不同载流子平衡能量分布的物质域而使载流子能量保持在非平衡状态的区域。研究了无序多组分非晶纳米复合材料结构中扩展态和局域态载流子的多模输运。这是一个新的科学问题，有许多尚未解决的科学问题。进一步了解这种非晶基材料中的电荷载流子和声子输运将直接影响其材料设计，并为电子应用提供新的材料结构。与理论研究并行，将开发一种高效且可扩展的自顶向下合成这种结构的方法。该材料是在单横模微波腔中加工的，这为快速方便地形成非晶材料的新状态提供了一条非凡的途径。脱晶过程只需将固体材料置于腔内强E或H场即可发生。这种方法可以在原位形成这种结构，这是传统的批量加工方法无法做到的。这种独特的性能为非平衡结构的工程研究开辟了新的领域。

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.