Radiative Thermal Transport with Nanowire-Based Uniaxial Electromagnetic Metamaterials
Technical Report,01 Dec 2016,30 Nov 2019
ARIZONA STATE UNIVERSITY Tempe United States
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This YIP project aims to obtain a deep fundamental understanding of radiative heat transfer between nanowire metamaterials from both theoretical and experimental studies. Over the 3-year duration, significant progress has been made. In particular, silicon-cored tungsten nanowires have been successfully fabricated and characterized, which exhibited excellent spectral selectivity with enhanced absorption within solar spectrum and low infrared thermal emission. By developing a lab-scale test platform, the solar-to-heat efficiency of these selective nanowire structures have been carefully measured to confirm the effect of spectral selectivity in enhanced thermal energy conversion. On the other hand, effective uniaxial materials properties i.e.,electric permittivity and magnetic permeability of metallic nanowire structures have been retrieved from far-field optical responses to successfully capture the effect of artificial magnetic resonance. With fluctuational electrodynamics calculation, the artificial magnetic resonance from the nanowires is theoretically demonstrated to greatly affect the near-field radiative heat transfer. Lastly, in order to experimentally study the near-field radiative heat transfer, a plate-plate thermal metrology is developed to study that between planar samples. Polystyrene nanoparticles were first used to create 215nm vacuum gaps between mm-scale aluminum thin film samples, which demonstrated more than 6 times enhancement over far-field blackbody limit between these metallic surfaces previously known as bad emitters. With patterned SU8 polymer posts, capacitance measurement was implemented to determine the gap distance in-situ during the near-field experiment for heavily doped silicon, which exhibits more than 11 times super-blackbody radiation heat transfer.
- Miscellaneous Materials
- Electricity and Magnetism