Synthesis and Characterization of New Zintl Phases for Thermoelectric Applications

非技术总结：先进材料的发展被广泛认为是新兴技术背后的关键因素之一，这些技术有可能实现可持续发展的环境，并为我们的星球提供充足的清洁能源。本提案的重点是合成和表征具有热电应用潜力的Zintl相。Zintl相是一类已经显示出重大前景的化合物，通过将这些材料制成的设备的效率提高一倍，改变了能量转换的格局。这一提议具有更广泛的影响，与下一代科学家的培训有关，使他们能够在未来几十年解决材料转化的需求。该提案支持少数族裔和女性在最初阶段(高中到大学（ACS SEED计划）和大学到研究生院（数学和物理科学本科生研究参与者指导计划，MURPPS），同时培训研究生从事科学事业。学生与喷气推进实验室的科学家合作，了解并提高热电应用材料的效率。学生通过实践训练、探索和向更广泛的科学界传播研究成果，发展科学、社会和专业技能。材料合成和结构-性能相关性的基础训练为热能到电能转换的发展和与技术相一致的多学科研究的进步提供了重要的基础。这项研究将在国内和国际会议上发表，研究结果将发表在同行评议期刊上。技术概述：热电材料将热直接转化为电，反之亦然。在材料研究部固态和材料化学项目的支持下，该项目专注于合成新的Zintl相，结合过渡金属和富含地球元素，以达到费米能级（通过部分填充d轨道）的高密度态（DOS），从而获得高塞贝克效应（功率因子）和高zT。相将通过熔剂、冶金路线和火花等离子烧结合成为单晶、高纯度粉末和颗粒。利用一系列物理表征技术，包括单晶和粉末x射线衍射，扫描电镜，元素波色散微探针，平行电和磁测量，结构和相组成将与电子和热输运性质相关。该项目的最终目标是发现具有高zT的新材料，用于将废热直接转化为电能。基于最近在Zintl相中显示的高zT的结果，本建议将合成策略与物理和化学性质的表征紧密联系起来，从而为指导这些热电系统的改进提供有效的反馈。

NON-TECHNICAL SUMMARY:The development of advanced materials is widely recognized as one of the key elements behind emerging technologies that can potentially achieve a sustainable environment and provide adequate, clean energy for our planet. This proposal is focused on the synthesis and characterization of Zintl phases with potential for thermoelectric applications. Zintl phases are a class of compounds that have already shown significant promise, changing the landscape of energy conversion by doubling the efficiencies of devices made with these materials. This proposal has broader impacts associated with training of the next generation of scientists, enabling them to tackle transforming materials needs over the next several decades. This proposal supports minorities and women at the initial stages (high school to college (ACS SEED program) and college to graduate school (Mentorships for Undergraduate Research Participants in Mathematical and Physical Sciences, MURPPS), along with training graduate students for scientific careers. Students collaborate with scientists at the Jet Propulsion Laboratory to understand and enhance the efficiencies for materials with promise for thermoelectric applications. Students develop scientific, social, and professional skills through hands-on training, exploration, and dissemination of research to the broader scientific community. Fundamental training in materials synthesis and structure-property correlations provides an important foundation for the development of thermal to electrical energy conversion and the advancement of multidisciplinary research aligned with technology. The research will be presented at national and international meetings and the findings published in peer-review journals.TECHNICAL SUMMARY:Thermoelectric materials convert heat directly into electricity or vice versa. With support of the Solid State and Materials Chemistry program in the Division of Materials Research, this project focuses on the synthesis of new Zintl phases, incorporating transition metals and earth abundant elements in order to target a high density of states (DOS) at the Fermi level (through partially filled d orbitals) to obtain high Seebeck effect (Power factor) and therefore high zT. Phases will be synthesized as single crystals, high purity powders and pellets via flux, metallurgical routes, and spark plasma sintering. Utilizing a suite of physical characterization techniques including single crystal and powder X-ray diffraction, SEM, elemental wave dispersive microprobe, parallel electrical and magnetic measurements, the structure and phase composition will be correlated with electronic and thermal transport properties. The ultimate goal of this project is to discover new materials with high zT for the direct conversion of waste heat into electricity. Building upon recent results of demonstrated high zT in Zintl phases, this proposal closely links synthetic strategies with characterization of physical and chemical properties, thus providing efficient feedback to guide improvement of these thermoelectric systems.