Tunable Super-Planckian Near-field Radiative Heat Transfer with Thermochromic Metamaterials

在零开氏度以上的有限温度下的材料可以在与具有受黑体限制的热通量的常规热辐射相关的长距离上发射传播电磁波，以及在距离远小于特征热波长时辐射热通量可能超过黑体限制的数量级的附近发射衰减波。本计画主要研究可调近场热致变色材料的辐射热输运，其颜色随温度变化。该项目可能影响许多潜在的能源应用，包括微电子的热管理和固态热电发电的能量转换。它还将为基于辐射的近场设备铺平道路，用于主动热控制，热电路和热计算机。研究成果将通过期刊出版物、会议报告和课程教学传播。PI将为下一代劳动力培训研究人员和领导者，强调代表性不足的群体的更广泛参与。研究生将学习多个学科的基础知识和技能。亚利桑那州立大学富尔顿本科生研究计划为本科生提供了一个很好的机会，参与PI实验室的研究活动。该研究项目旨在通过亚利桑那州立大学的各种项目，促进对可调近场辐射热传输的基本理解，该研究基于不同的物理机制，利用热致变色超材料跨越纳米真空间隙，超普朗克热通量超过黑体极限。二氧化钒作为一种独特的热致变色材料，当温度超过68°C时，会发生绝缘体-金属相变。理论计算的基础上结合薄膜单轴波光学波动电动力学以及严格的耦合波分析的基础上的数值模拟将实施预测光谱和总辐射热通量与不同的热致变色纳米结构。先进的纳米制造方法，包括薄膜沉积，深紫外光刻和电子束光刻将用于制造所设计的热致变色纳米结构，而独特的技术，如温度依赖的红外光谱将被用来表征所制造的样品的辐射热性能。新的近场热计量，可以实现低至100 nm的真空间隙将被用于近场辐射热传递的实验研究，以了解不同的物理机制如何使不同的热致变色纳米结构的相变时的可调热通量。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进行评估，被认为值得支持。

Materials at finite temperature above zero Kelvin can emit propagating electromagnetic waves over long distances related to conventional thermal radiation with heat flux limited by blackbodies, as well as decaying waves in close proximity where radiative heat flux could exceed the blackbody limit by orders of magnitude when the distance is much smaller than the characteristic thermal wavelength. This project studies tunable near-field radiative thermal transport with thermochromic materials whose color changes with temperature. The project could impact many potential energy applications including thermal management of microelectronics and energy conversion in solid-state thermopower generation. It will also pave the way to radiation-based near-field devices for active heat control, thermal circuits and thermal computers. The research outcomes will be disseminated through journal publications, conference presentations and course teaching. The PI will train researchers and leaders for the next generation of work force, emphasizing on broader participation of underrepresented groups. Graduate students will learn the fundamentals and skills of multiple disciplines. The Arizona State Fulton Undergraduate Research Initiative program offers a great opportunity for undergraduate students to participate in the research activities in the PI’s lab. The PI will engage local K-12 students and reach out to local public and society through various programs at ASU.This research project aims to advance the fundamental understanding in tunable near-field radiative thermal transport with thermochromic metamaterials across nanometric vacuum gaps based on different physical mechanisms with super-Planckian heat flux exceeding the blackbody limit. Vanadium dioxide as one unique thermochromic material could experience insulator-to-metal phase transition when its temperature increases beyond 68°C. Theoretical calculations based on fluctuational electrodynamics incorporated with thin-film uniaxial wave optics as well as numerical modeling based on rigorous coupled-wave analysis will be implemented to predict the spectral and total radiative heat flux with different thermochromic nanostructures. Advanced nanofabrication methods including thin-film deposition, deep-UV lithography and electron-beam lithography will be used to fabricate the designed thermochromic nanostructures, while unique techniques such as temperature-dependent infrared spectroscopy will be employed to characterize the radiative thermal properties of fabricated samples. Novel near-field thermal metrology that could achieve down to 100-nm vacuum gaps will be utilized for the experimental study of near-field radiative heat transfer to understand how different physical mechanisms enable the tunable heat flux upon phase transition of different thermochromic nanostructures. Potential applications such as near-field radiative thermal rectification and switching will be experimentally demonstrated.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.