GOALI Collaborative Research: Intrinsically Minimal Thermal Conductivity in I-V-VI2 Thermoelectric Semiconductors

CBET-0754029 Morelli这项工作的目标是为开发基于I-V-VI2化合物的新型热电半导体奠定科学基础。这类化合物本质上是晶体材料中晶格导热系数最低的。低的晶格热导率是产生高热电优值的主要因素之一；ii)本方案的PI设计了一种制备具有非常低的载流子浓度和高迁移率的AgSbTe2的方法。该项目是BSST作为行业合作伙伴的一个目标。与世界上最大的热电材料用户BSST合作，将确保对所生产的任何新材料的商业潜力进行快速评估。智力价值这项研究将集中于对这类半导体的晶格和电子性质的严格实验研究。以Ag/Sb有序度为独立参数，测量了从4K到熔点的晶格热导率。这些数据将被解释为UmkLapp和正常的声子散射过程，这些过程将不使用可调整的弛豫时间，以及键的非谐性。详细的能带结构和费米面信息将从Shubnikov-DeHaas测量中收集到。初步的第一性原理计算表明，AgSbTe2实际上可能是半金属的，其确切的能带结构又是Ag/Sb有序量的函数。完整的电磁场、热电和热磁性质将被测量到熔点，并用于确定迁移率和电子散射机制。广泛影响增强的热电材料将实现一种将太阳能转换为电能的廉价方法，还将使传统热机(如汽车发电厂)浪费的一小部分热转化为可用能源成为可能。因此，这是一项潜在的变革性研究，有望减少我们对化石燃料的依赖，并不仅对科技界，而且对整个社会产生重大的积极影响。与BSST的合作将确保新的热电材料迅速可用于评估其商业潜力。BSST将向研究团队反馈有关工程标准和新材料在真实发电机中的实际性能的重要信息。在教育领域，该项目将为研究生提供广泛的材料合成和表征技术方面的培训。此外，研究成果将被纳入皮？S正在开发的热运输和热电领域的课程。这项研究解决的能源效率和使用这一更广泛问题的重要性将被纳入这两个机构成熟的推广计划中。该项目由化学、生物工程、环境和运输系统(CBET)分部的热传输过程(TTP)计划和工业创新与合作伙伴(IIP)分部的学术联系机会(GOALI)计划联合资助。

CBET-0754029MorelliThe goal of this work is to lay the scientific groundwork to develop a new class of thermoelectric semiconductors based on I-V-VI2 compounds. This class of compounds possesses intrinsically the lowest lattice thermal conductivity possible in a crystalline material. Low lattice thermal conductivity is one of the prime factors in producing a high thermoelectric figure of merit; and ii) the PIs of this proposal have devised a method for preparing AgSbTe2 with very low carrier concentrations and high mobilities. The program is a GOALI with BSST as an industrial partner. Partnership with BSST, the world's largest user of thermoelectric materials, will ensure a rapid evaluation of the commercial potential of any new material produced. Intellectual MeritThis research will focus on rigorous experimental studies of the lattice and electronic properties of this class of semiconductors. The lattice thermal conductivity will be measured from 4 K to the melting point, with the Ag/Sb ordering as independent parameter. The data will be interpreted in terms of Umklapp and Normal phonon scattering processes, which will be derived without using adjustable relaxation times, and of the bond anharmonicity. Detailed band structure and Fermi surface information will be gleaned from Shubnikov-deHaas measurements. Preliminary first principle calculations show that AgSbTe2 may actually be a semimetal, and that its exact band structure is a function again of the amount of Ag/Sb ordering. The full galvanomagnetic, thermoelectric and thermomagnetic properties will be measured up to the melting point, and used to determine mobilities and electron scattering mechanisms. Broad ImpactEnhanced thermoelectric materials will enable an inexpensive method for converting solar thermal energy into electricity, and also will make possible the conversion of a fraction of the heat wasted by conventional heat engines, such as automotive power plants, into usable power. This is thus potentially transformative research that promises to reduce our reliance on fossil fuels, and to have a significant positive impact not only on the science and technology community, but on society in general. The partnership with BSST will ensure that the new thermoelectric materials are rapidly available for evaluation of their commercial potential. BSST will feed important information back to the research team about engineering criteria and the actual performance of the new materials in real electrical power generators. In the realm of education, this project will provide training for graduate students in a broad array of materials synthesis and characterization techniques. Additionally, results of the research will be incorporated into classes being developed by the PI?s in the areas of thermal transport and thermoelectricity. The significance of the broader issue of energy efficiency and usage that this research addresses will be integrated into the well established outreach programs at both institutions. Finally, the involvement of an industrial partner will give the students real-world experience into the engineering of transformative technological products and insight into the world of the energy industry.This project is jointly funded by the Thermal Transport Processes (TTP) Program, of the Chemical, Bioengineering, Environmental, and Transport Systems (CBET) Division, and by the Grant Opportunities for Academic Liaison with Industry (GOALI) Program, of the Industrial Innovation & Partnerships (IIP) Division, all within the Directorate for Engineering (ENG).