Unlocking the Potential of Zintl Compounds for Thermoelectrics

在美国国家科学基金会材料研究部固态和材料化学项目的支持下，首席研究员和她在加州大学戴维斯分校的研究小组合成并表征了新的Zintl化合物。锌相是由金属元素组成的化合物，但具有半导体的性质。这种材料具有潜在的优良热电性能。更便宜的热电材料可以将废热转化为可用的电力，减少我们对化石燃料的依赖，从而改变世界的能源格局。材料的能量转换效率要求像金属一样的低电阻率和像绝缘体一样的低导热性。Zintl相的组成和结构的独特组合可以产生特殊的热电性能，可以通过系统取代单个元素进一步优化。该项目开发了新的结构，并优化了高效热电材料的性能。在此奖项期间，为研究生开设了一门新的课程，重点是弹性，心理健康和福祉。该项目还培养了年轻科学家在结构确定和性能测量以及热电设计和优化方面的能力。研究生和本科生的科学和社会技能是通过研讨会、专题讨论会和个性化指导来发展的。第2部分：技术概述：需要高效的热电材料来影响能量转换技术。该项目得到了美国国家科学基金会材料研究部固态和材料化学项目的支持，通过通量和直接合成提供了新的Zintl相化合物，并以发现新的热电材料为目标描述了它们的特性。具有良好性质的化合物可以进一步优化其热电效率，为科学界提供新的研究方向。目标包括合成尚未被研究的新化合物，例如Zintl相的形态优化。合成了二维（层状）和一维（链状）相，并对其性质进行了表征。这些新相的性质将通过异价和同价取代得到增强，以获得更好的热电行为。研究生和本科生学习一套物理表征技术，以及如何将结构和相组成与电子和热输运性质联系起来。与加州大学戴维斯分校研究生部合作，在该奖项的时间框架内教授和评估心理健康和科学弹性课程。研究生和本科生可以通过研讨会、专题讨论会和指导来发展他们的科学和社会技能。这项研究将在全国会议上传播，研究结果将发表在同行评议的期刊上。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

PART 1: NON-TECHNICAL SUMMARY With support from the Solid State and Materials Chemistry program in NSF’s Division of Materials Research, the principal investigator and her research group at the University of California Davis synthesize and characterize new Zintl compounds. Zintl phases are compounds composed of metallic elements but have the properties of a semiconductor. This type of material has potentially excellent thermoelectric properties. Less expensive thermoelectric materials could alter the world’s energy landscape by converting waste heat into usable electricity and reducing our dependence on fossil fuels. The energy conversion efficiency of a material requires low electrical resistivity like a metal and low thermal conductivity as in an insulator. The unique combination of composition and structure of Zintl phases can give rise to exceptional thermoelectric properties that can be further optimized by systematic substitution of individual elements. This project develops new structures and optimizes properties toward high efficiency thermoelectric materials. A new course for graduate students focused on resiliency, mental health and well-being is developed and assessed during the time of this award. This project also trains young scientists in structure determination and property measurements along with thermoelectric design and optimization. Graduate and undergraduate students’ scientific and social skills are developed through workshops, symposiums, and individualized mentoring. PART 2: TECHNICAL SUMMARY Efficient thermoelectric materials are required to impact energy conversion technologies. This project, with support from the Solid State and Materials Chemistry program in NSF’s Division of Materials Research, provides new Zintl phase compounds via flux and direct synthesis and characterizes their properties with a goal of discovering new thermoelectric materials. Compounds with promising properties are then further optimized for their thermoelectric efficiency and provide new directions of research for the scientific community. Goals include the the synthesis of new compounds that have not yet been investigated and, e.g. morphological optimization of Zintl phases. Two-dimensional (layered) and one-dimensional (chain) containing phases are synthesized and their properties characterized. The properties of these new phases will be enhanced with alio- and iso-valent substitution towards better thermoelectric behavior. Graduate and undergraduate students learn a suite of physical characterization techniques and how to correlate structure and phase composition with electronic and thermal transport properties. In collaboration with the UC Davis graduate division, a mental wellness and scientific resiliency course is taught and assessed during the timeframe of this award. Graduate and undergraduate students can develop their scientific and social skills through workshops, symposiums, and mentorship. The research will be disseminated at national meetings and findings published in peer-reviewed journals.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.