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

非晶态材料可能具有与晶态或纳米晶态相同材料根本不同的电学和热学性质。尽管非晶态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传输仍然是一个争议点。非晶态材料缺乏长程和短程有序性，导致结构和能量输运之间复杂的相互作用。在这个项目中，将开发一种以非晶-晶态纳米复合材料形式的大块非晶结构的新型电子材料，并对其热学和电学性能进行定制。这项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。在开展研究工作的同时，还将实施一项教育计划，在高年级本科课程中纳入和发展一项新的教学举措，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，并提供高级热电材料研究的资源网站。俄克拉荷马州路易斯·斯托克斯少数民族参与联盟(OK-LSAMP)和多元文化工程计划(MEP)计划中的可用资源将用于扩大少数族裔学生的参与和招收高中生。这项研究计划解决了对非晶态材料中电荷和声子传输的物理描述的基本需求，表征了它们的结构相关性，并应用这种理解来增强非晶态材料的热电性能和非晶态晶体纳米复合材料的更复杂结构。尤其是在载流子能量由于连续通过具有不同平衡载流子能量分布的材料区域而保持非平衡态的区域。我们将讨论无序多组分非晶-晶体纳米复合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，有许多悬而未决的科学问题。深入了解这类非晶态材料中的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。在理论研究的同时，将开发一种有效的、可扩展的自上而下合成此类结构的方法。材料在单个横模微波腔中进行处理，这为以相当快速和方便的方式创造非晶态材料的新状态提供了一条非凡的途径。脱结晶过程只需将固体材料置于腔内的强E或H场中即可。该方法导致这种结构的原位形成，这是传统的块状加工方法不可能实现的。这种独特的能力为工程非平衡结构开辟了一片新的天地。

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.