Synthesis of Zintl Phases for Thermoelectric Applications

用于热电应用的 Zintl 相的合成

• 批准号: 1100313
• 负责人: Susan Kauzlarich
• 金额: $ 50万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1100313&HistoricalAwards=false
• 关键词: Synthesis; Zintl; Phases; Thermoelectric; Applications

TECHNICAL SUMMARY: This project, supported by the Solid State and Materials Chemistry program focuses on the synthesis of new Zintl phases, incorporating transition metals in order to target a high density of states (DOS) at the Fermi level (through partially filled d orbitals) to obtain high Seebeck coefficient (Power factor) and therefore high zT. Nanostructuring will be employed to further reduce the thermal conductivity. Phases will be synthesized via flux and metallurgical routes. Utilizing a suite of physical characterization techniques including single crystal and powder X-ray diffraction, SEM and TEM, elemental wave dispersive microprobe and ICP-MS analysis, parallel electrical and magnetic measurements, the structure and phase composition will be correlated with electronic and thermal transport properties. The ultimate goal of the 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.NON-TECHNICAL SUMMARY: Thermoelectric devices for power generation convert thermal energy directly into electrical energy, require minimal maintenance, and can be operated over a large temperature range (room temperature to 1000 degrees C). Thermoelectric materials are described by a figure of merit, zT, which relates to how well a material converts heat flow to electricity - the higher the value, the greater the efficiency. Recent discoveries of Zintl phases with zT of 1.0 or greater highlight the importance of continued exploration of new materials. A Zintl phase is a compound which contains both cations such as alkali, alkaline earth, and rare earth elements which donate electrons to polyanionic units composed of main group elements such as those from groups 13, 14, and 15 of the periodic table. These types of compounds naturally provide low thermal conductivity which is a requirement for thermoelectric devices. With higher zT, the potential for solid-state power generation from waste heat recovery provides a framework for investigating new Zintl phase materials with stability and optimal properties at high temperatures (300 degrees C). This project supports minorities and women at the initial stages (high school to college and college to graduate school), along with training graduate student for scientific careers. Students develop scientific, social, and professional skills through hands-on training, exploration, and dissemination of research to the broader scientific community. The topics under study include materials synthesis and property measurements, fundamental training in materials synthesis and structure-property correlations, providing 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. Additionally, the PI supports students through the ACS SEED program (high school), MURPPS (undergraduate), and AGEP (graduate) programs focused on increasing underrepresented groups in science on campus. The ChemWiki will be employed to enhance student learning through writing and critical evaluation.

技术摘要：该项目由固态和材料化学计划支持，重点是合成新的 Zintl 相，并掺入过渡金属，以实现费米能级的高态密度 (DOS)（通过部分填充的 d 轨道）获得高塞贝克系数（功率因数），从而获得高 zT。将采用纳米结构来进一步降低导热率。各相将通过熔剂和冶金途径合成。利用一系列物理表征技术，包括单晶和粉末 X 射线衍射、SEM 和 TEM、元素波色散微探针和 ICP-MS 分析、并行电学和磁学测量，结构和相组成将与电子和热传输相关联特性。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 Zintl 相中高 zT 的最新结果，该提案将合成策略与物理和化学性质的表征紧密联系起来，从而提供有效的反馈来指导这些热电系统的改进。非技术摘要：用于发电的热电装置将热能转化为热能。将能量直接转化为电能，需要最少的维护，并且可以在很大的温度范围内运行（室温至 1000 摄氏度）。热电材料用品质因数 zT 来描述，它与材料将热流转化为电能的能力有关 - 值越高，效率越高。最近发现的 zT 为 1.0 或更高的 Zintl 相凸显了继续探索新材料的重要性。 Zintl相是含有阳离子例如碱金属、碱土金属和稀土元素的化合物，其向由主族元素例如周期表第13、14和15族元素组成的聚阴离子单元提供电子。这些类型的化合物自然提供低导热率，这是热电装置的要求。凭借更高的 zT，利用废热回收进行固态发电的潜力为研究在高温（300 摄氏度）下具有稳定性和最佳性能的新型 Zintl 相材料提供了一个框架。该项目在初始阶段（高中到大学、大学到研究生院）为少数族裔和妇女提供支持，并培训研究生从事科学职业。学生通过实践培训、探索和向更广泛的科学界传播研究成果来培养科学、社会和专业技能。研究课题包括材料合成和性能测量、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以及与技术相关的多学科研究的进步提供重要基础。该研究将在国内和国际会议上展示，研究结果将在同行评审期刊上发表。此外，PI 还通过 ACS SEED 计划（高中）、MURPPS（本科生）和 AGEP（研究生）计划为学生提供支持，这些计划致力于增加校园科学领域中代表性不足的群体。 ChemWiki 将用于通过写作和批判性评估来增强学生的学习。