Rational Design of Thermoelectric Materials and Material Processing Approaches Based on Microwave Processing of Silicides

基于硅化物微波加工的热电材料及材料加工方法的合理设计

• 批准号: 1522513
• 负责人: Daryoosh Vashaee
• 金额: $ 42.5万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-10-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1522513&HistoricalAwards=false
• 关键词: Rational; Design; Thermoelectric; Materials; Material

Thermoelectric materials are materials that can produce an electric current when two sides of the material are exposed to different temperatures or vice-versa (i.e., supplying an electric voltage and current to a thermoelectric material can change the temperature of its surfaces). Thermoelectric materials are a promising technology for a range of application from electric power generation to heating and cooling. Most electric power today is produced from processes where fuel is burned to produce heat that turns water into steam that is then used to turn electric power generators, and low temperature steam is exhausted as waste. Such processes are relatively inefficient, converting only about 30 to 40 percent of the fuel's energy into useful electric power. Thermoelectric materials could be used to convert this wasted thermal energy into useful electric power. The team will design and construct high efficiency thermoelectric materials and devices from composite materials constructed from combinations of amorphous (i.e., non-crystalline, molecularly disordered) and crystalline materials that can maximize the material's electrical conductivity while minimizing the material's thermal conductivity, an ideal combination for effective thermoelectricity. The project will have broad educational impacts through both development of nanotechnology related university-level coursework and through the direct involvement of underrepresented students in the research.The primary focus of the work will be on the use of composite silicide (i.e., materials that combine silicon with other elements such as metals) to create highly efficient thermoelectrics. The target of more efficient thermoelectric materials is to achieve a large thermoelectric effect so that large amounts of electric power can be generated from relatively small temperature differences between waste heat sources and the environment. This project is a computationally guided material design effort which encompasses both theoretical and experimental aspects of amorphous based materials. The program addresses the multi-mode transport of charge carriers in extended and localized states, along with phonon transport properties in disordered multi-component amorphous structures. It is expected that new material structures based on amorphous-crystalline composites of silicide alloys developed in this work should result in significant nonlinear enhancement of the thermoelectric power factor, along with the reduction of the thermal conductivity of the materials. This research concept is a nanoscale effect that happens only if the energy distribution function of the carriers does not relax to that of the bulk material in the crystallites. This state requires crystallite sizes of sub-10 nm in most thermoelectric materials, which is often difficult to reach with the existing material processing methods. This project will develop a new material synthesis method based on field decrystallization in a microwave cavity that can produce non-equilibrium silicide materials. The effect of hydrogenation on thermoelectric properties will be investigated for the first time, and the scalability of the material growth technique will be demonstrated

热电材料是当材料的两面暴露在不同的温度下或反之亦然时可以产生电流的材料（即，向热电材料提供电压和电流可以改变其表面的温度）。热电材料是一种很有前途的技术，从发电到加热和冷却。今天的大多数电力都是通过燃烧燃料来产生热量，将水转化为蒸汽，然后用来驱动发电机，低温蒸汽作为废物被排出。这种过程效率相对较低，只能将大约30%到40%的燃料能量转化为有用的电能。热电材料可用于将这些浪费的热能转化为有用的电能。该团队将设计和构建高效热电材料和器件，这些材料是由非晶（即非晶，分子无序）和晶体材料组合而成的复合材料，可以最大化材料的导电性，同时最小化材料的导热性，这是有效热电的理想组合。该项目将通过开发与纳米技术相关的大学课程，以及通过让代表性不足的学生直接参与研究，对教育产生广泛的影响。这项工作的主要重点将是使用复合硅化物（即将硅与其他元素（如金属）结合在一起的材料）来制造高效的热电材料。更高效的热电材料的目标是实现大的热电效应，以便从废热源和环境之间相对较小的温差中产生大量的电力。这个项目是一个计算指导的材料设计工作，包括非晶基材料的理论和实验方面。该程序解决了扩展和局部状态下载流子的多模输运，以及无序多组分非晶结构中的声子输运性质。期望在本工作中开发的基于硅化合金非晶复合材料的新材料结构将导致热电功率因子的显著非线性增强，以及材料导热系数的降低。这个研究概念是一种纳米级效应，只有当载流子的能量分布函数不松弛到晶体中大块材料的能量分布函数时才会发生。在大多数热电材料中，这种状态要求晶体尺寸小于10 nm，而现有的材料加工方法往往难以达到这一水平。本项目将开发一种基于微波腔场脱晶的新型材料合成方法，可制备非平衡硅化物材料。氢化对热电性能的影响将首次被研究，并将证明材料生长技术的可扩展性