Near-field radiative heat transfer enhancement using natural hyperbolic material

Hyperbolic materials have been newly discovered that can enhance near-field radiative transfer. Multi-layer and three-dimensional hyperbolic materials require challenging fabrication techniques. From a practical point of view, natural hyperbolic materials serve better in applications requiring near-field radiative transfer enhancement. In this study, we investigate enhancement of near-field radiative transfer using natural hyperbolic material - calcite, and compare with that from (also natural) polar dielectric materials, SiC, where phonon polaritons are responsible for enhanced near-field heat transfer. Spectral analyses of enhanced near-field radiative transfer from hyperbolic modes in hyperbolic materials and surface phonon polaritons in polar dielectric materials are carried out and compared, which determine the origin and amount of near-field radiative transfer enhancement in these materials. (C) 2018 Elsevier Ltd. All rights reserved.