CAREER: Interface Formation in Laser Processed Thermoelectric Materials

该学院早期职业发展（CAREER）资助整合了先进的材料和制造技术，以创建下一代能源设备。能源材料和设备的先进制造具有改变能源效率格局的潜力。超过50%的能源被浪费在热能上。热电装置将温度变化转换为电压变化，将热量直接转换为电能，可以显著提高能源效率并实现分布式发电。为了将这些材料投入广泛使用，需要一种能够实现有效材料工程和集成以及可定制设备设计的制造方法。增材制造，特别是基于激光的增材制造，提出了一种能够实现广泛的热电设备制造的潜在解决方案。然而，人们对增材制造中的激光加工（材料在此期间快速熔化和重新固化）如何影响热电材料的结构和性能知之甚少。该研究项目旨在揭示快速熔化和凝固与由此产生的纳米，微米和介观尺度结构之间的关系，并了解这些结构对热电材料的热和电性能的影响。该研究与教育和推广方法相结合，该方法使用材料科学，制造和能源工程作为平台，以扩大和多样化工程劳动力，并为未来的劳动力创造教育和专业发展经验，这些劳动力能够在技术设计，开发，本项目研究激光加工产生的界面如何改变热电材料的传输特性。该项目将研究激光诱导熔化和固化产生的界面密度是否会导致热导率降低和热电功率因数增加。激光加工参数决定了温度梯度的时间和空间变化，这些梯度决定了界面形成的时间、地点和时间。这些界面的大小、密度和位置决定了它们将如何影响能量载体传输。研究方法是通过实验和计算研究工艺-结构-性能关系，通过（1）实验表征多尺度结构和性能，以及（2）模拟随时间变化的三维温度梯度沿着形成微结构晶体形态。该项目的重点是以晶粒、位错、相分离和点缺陷的形式存在的界面。这项工作使激光加工工程师接口（并因此控制能量载体传输），并且它将激光粉末床熔合从主要限于金属的制造技术推进到包括半导体的制造技术-为新的，该奖项反映了NSF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。

This Faculty Early Career Development (CAREER) grant integrates advanced materials and manufacturing techniques to create next-generation energy devices. Advanced manufacturing of energy materials and devices has the potential to transform the energy efficiency landscape. Over fifty percent of energy resources are wasted as heat. Thermoelectric device, which convert a temperature change to a voltage change, convert heat directly into electricity, and can dramatically improve energy efficiency and enable distributed electricity generation. To put these materials into widespread use, a manufacturing approach that enables effective materials engineering and integration as well as customizable device design is needed. Additive manufacturing, particularly laser-based additive manufacturing, presents a potential solution to enable widespread thermoelectric device fabrication. Very little is known, however, about how laser processing in Additive Manufacturing (during which materials rapidly melt and re-solidify) impacts thermoelectric materials' structure and properties. This research project aims to uncover the relationship between rapid melting and solidification and the resulting nano-, micro-, and meso-scale structures, and understand the impact of these structures on thermal and electrical properties of thermoelectric materials. The research is integrated with an educational and outreach approach that uses materials science, manufacturing, and energy engineering as a platform to broaden and diversify the engineering workforce and create educational and professional development experiences for a future workforce that is equipped to prosper in technology design, development, and deployment.This project investigates how the interfaces created by laser processing alter the transport properties of thermoelectric materials. The project will examine whether the interface density resulting from laser-induced melting and solidification causes the thermal conductivity to decrease and the thermoelectric power factor to increase. Laser processing parameters determine the temporal and spatial variation of the temperature gradients, and these gradients determine what, where, and when interfaces form. The size, density, and location of those interfaces determine how they will impact energy carrier transport. The research approach is to experimentally and computationally investigate the process-structure-property relationship by (1) experimentally characterizing the multi-scale structures and properties and (2) modeling the time-varying, three dimensional temperature gradients along with the formation of microstructural crystalline morphologies. The project focuses on interfaces in the form of grains, dislocations, phase segregation, and point defects. This work enables laser processing to engineer interfaces (and thus control energy carrier transport) in semiconductor materials, and it advances laser powder bed fusion from a manufacturing technology limited mostly to metals to one that includes semiconductors–paving the way for additive manufacturing of new, multifunctional structures.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.