Radiative Thermal Rectification between SiC and SiO2

TL;DR

This paper investigates radiative thermal rectification between SiC and SiO2 using fluctuation electrodynamics, revealing significant near-field effects and temperature-dependent rectification influenced by surface polariton behavior.

Contribution

It provides the first detailed analysis of thermal rectification between SiC and SiO2 considering near-field effects and temperature variations using experimental optical data.

Findings

Rectification is stronger at smaller separation distances.

Larger temperature differences lead to increased rectification.

Surface polariton weakening in SiC at higher temperatures enhances rectification.

Abstract

By means of fluctuationnal electrodynamics, we calculate radiative heat flux between two pla-nar materials respectively made of SiC and SiO2. More specifically, we focus on a first (direct) situation where one of the two materials (for example SiC) is at ambient temperature whereas the second material is at a higher one, then we study a second (reverse) situation where the material temperatures are inverted. When the two fluxes corresponding to the two situations are different, the materials are said to exhibit a thermal rectification, a property with potential applications in thermal regulation. Rectification variations with temperature and separation distance are here reported. Calculations are performed using material optical data experimentally determined by Fourier transform emission spectrometry of heated materials between ambient temperature (around 300 K) and 1480 K. It is shown that rectification is much more important in the near-field domain, i.e. at separation distances smaller than the thermal wavelength. In addition, we see that the larger is the temperature difference, the larger is rectification. Large rectification is finally interpreted due to a weakening of the SiC surface polariton when temperature increases, a weakening which affects much less SiO2 resonances.