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

CBET-0754023 Heremans这项工作的目标是为开发基于I-V-VI 2化合物的新型热电半导体奠定科学基础。 这类化合物本质上具有晶体材料中可能的最低晶格热导率。低晶格热导率是产生高热电品质因数的主要因素之一;以及ii）本提案的PI已经设计了一种用于制备具有非常低的载流子浓度和高迁移率的AgSbTe 2的方法。 该计划是一个目标与BSST作为工业合作伙伴。 与世界上最大的热电材料用户BSST的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。 智力优点这项研究将集中在这类半导体的晶格和电子特性的严格实验研究。 晶格热导率将从4 K到熔点测量，Ag/Sb有序作为独立参数。这些数据将被解释Umklapp和正常声子散射过程，这将是不使用可调弛豫时间，和债券的非谐性。 详细的能带结构和费米面信息将收集从舒布尼科夫-德哈斯测量。 初步的第一性原理计算表明，AgSbTe 2实际上可能是一种半金属，其确切的能带结构是Ag/Sb有序量的函数。完整的电磁，热电和热磁特性将被测量到熔点，并用于确定迁移率和电子散射机制。 增强型热电材料将使一种廉价的方法将太阳热能转化为电能，也将使传统热机（如汽车发电厂）浪费的一小部分热量转化为可用的电力成为可能。 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，不仅对科学技术界，而且对整个社会产生重大的积极影响。与BSST的合作伙伴关系将确保新的热电材料能够迅速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的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，研究结果将被纳入正在开发的类PI？在热传输和热电领域。这项研究所涉及的能源效率和使用的更广泛问题的重要性将被纳入这两个机构的既定推广计划。 最后，工业合作伙伴的参与将为学生提供变革性技术产品工程的真实经验，并深入了解能源行业的世界。该项目由化学，生物工程，环境和运输系统（CBET）部门的热传输过程（TTP）计划共同资助，以及工业创新伙伴关系（IIP）部门的学术与工业联络（GOALI）计划的资助机会&，所有这些都在工程局（ENG）内。

CBET-0754023HeremansThe 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).