CAREER: Overcoming the trade-off between thermopower and conductivity in transition metal oxides

职业生涯：克服过渡金属氧化物热电势和电导率之间的权衡

• 批准号: 2340234
• 负责人: Dongkyu Lee
• 金额: $ 61.92万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-09-01 至 2029-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2340234&HistoricalAwards=false
• 关键词: CAREER; Overcoming; trade; off; between

Nontechnical DescriptionNearly two-thirds of the total energy generated by humanity is wasted as heat. In the face of growing concerns about climate change, efficient recycling of waste heat is an urgent significant scientific challenge. The thermoelectric (TE) conversion process transforms waste heat into usable electric power, providing a promising source of clean and sustainable energy. The efficiency of this process depends on the intrinsic properties of materials, particularly thermopower and electrical conductivity. Yet, current oxide material systems and engineering designs face challenges in achieving favorable TE properties. The discovery of new materials with good TE properties and designs to take advantage of them is therefore crucial for the development of high-performance TE devices. This project focuses on transition metal oxides, which are promising TE materials due to their non-toxic nature, abundance, and stability at high temperatures. This project aims to establish a novel approach for achieving large thermopower and high conductivity in transition metal oxides. This approach combines a new oxide heterostructure with columnar microstructures and vertical interfaces, along with the addition of metal nanoparticles. The PI is committed to elevating public awareness of the pivotal role of materials science and fostering the growth of future materials scientists and engineers. Towards this end, the PI plans to provide lectures and science demonstrations on oxides to high school students and teachers. Furthermore, hands-on research training and mentorship opportunities are provided for underrepresented undergraduate and graduate students to spark interest in materials science engineering studies and related careers.Technical DescriptionTo meet the growing demand for high-temperature TE devices capable of converting waste heat into electricity, it is indispensable to discover transition metal oxides (TMOs) with large thermopower and high electrical conductivity, enabling a substantial power factor. Nevertheless, due to the inherent trade-off relationship between enhancing conductivity and thermopower, achieving TMOs with simultaneously high values of both properties remains a formidable challenge. The overarching goal of this project is to overcome this trade-off by establishing a completely new approach that combines two emerging strategies: vertical strain and the unique redox defect chemistry of TMOs. The PI plans to explore the relationships between strain, redox defects, and TE properties in TMOs by synthesizing vertically aligned nanocomposites composed of two different perovskites through pulsed laser deposition in combination with the exsolution of metal nanoparticles. In perovskite materials with A-site deficiencies, metal exsolution occurs during reduction, leading to an energy filtering effect that enhances thermopower while preserving conductivity with minimal deterioration. Simultaneously, by maximizing tensile strain along the vertical interface in vertically aligned nanocomposites, the concentration of oxygen vacancies in electron-doped perovskites significantly increases, leading to an enhancement of conductivity. The fundamental knowledge gained on the relationships between strain, redox defects, and TE properties in this project provides unprecedented design freedom and facilitates the development of oxide TE materials with superior properties. In addition, this project benefits from the use of cutting-edge techniques in national laboratory user facilities, enhancing the precision and depth of the investigations. The innovative approach in this project can serve as a versatile architecture capable of accommodating a diverse array of functional properties, leading to advancements in a wide range of energy and electronic applications, ultimately benefiting the public.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.

非技术描述人类产生的总能量中近三分之二被浪费为热量。面对人们日益关注的气候变化，有效回收废热是一项紧迫的重大科学挑战。热电（TE）转换过程将废热转化为可用的电力，提供了一种有前景的清洁和可持续能源。该过程的效率取决于材料的固有特性，特别是热电性和电导率。然而，当前的氧化物材料系统和工程设计在实现良好的 TE 性能方面面临着挑战。因此，发现具有良好 TE 性能的新材料以及利用它们的设计对于高性能 TE 器件的开发至关重要。该项目重点研究过渡金属氧化物，由于其无毒性质、丰富性和高温稳定性，它们是有前途的 TE 材料。该项目旨在建立一种新方法来实现过渡金属氧化物的大热电势和高电导率。这种方法将新型氧化物异质结构与柱状微结构和垂直界面相结合，并添加了金属纳米颗粒。 PI 致力于提高公众对材料科学关键作用的认识，并促进未来材料科学家和工程师的成长。为此，PI 计划为高中生和教师提供有关氧化物的讲座和科学演示。此外，还为代表性不足的本科生和研究生提供实践研究培训和指导机会，以激发他们对材料科学工程研究和相关职业的兴趣。技术说明为了满足对能够将废热转化为电能的高温 TE 设备不断增长的需求，寻找具有大热电势和高电导率、实现高功率因数的过渡金属氧化物（TMO）是必不可少的。然而，由于增强电导率和热电势之间固有的权衡关系，实现同时具有两种特性的高值的 TMO 仍然是一个艰巨的挑战。该项目的总体目标是通过建立一种全新的方法来克服这种权衡，该方法结合了两种新兴策略：垂直应变和 TMO 独特的氧化还原缺陷化学。该项目负责人计划通过脉冲激光沉积结合金属纳米颗粒的溶出，合成由两种不同钙钛矿组成的垂直排列纳米复合材料，探索 TMO 中应变、氧化还原缺陷和 TE 性能之间的关系。在具有 A 位缺陷的钙钛矿材料中，还原过程中会发生金属脱溶，从而产生能量过滤效应，增强热电势，同时保持导电性，同时将恶化程度降至最低。同时，通过最大化垂直排列的纳米复合材料中沿垂直界面的拉伸应变，电子掺杂钙钛矿中氧空位的浓度显着增加，从而导致电导率增强。在该项目中获得的关于应变、氧化还原缺陷和 TE 性能之间关系的基础知识提供了前所未有的设计自由度，并促进了具有优异性能的氧化物 TE 材料的开发。此外，该项目受益于国家实验室用户设施中尖端技术的使用，提高了调查的精度和深度。该项目的创新方法可以作为一种多功能架构，能够容纳多种功能特性，从而促进广泛的能源和电子应用的进步，最终使公众受益。该奖项反映了 NSF 的法定使命，并被视为值得通过使用基金会的智力优点和更广泛的影响审查标准进行评估来支持。