Reflectance spectral studies of spark plasma sintered tungsten carbide pellet

We report the first spectral reflectance of tungsten carbide (WC) as potential solar selective absorber. We developed an optical measurement system for visible to mid-infrared spectroscopy, covering the range of 0.1-2.5 eV, to evaluate the solar selectivity. A polycrystalline WC was prepared using spark plasma sintering method. The measured spectral reflectance of WC exhibits a low-energy plasma excitation around 0.6 eV corresponding to the cutoff energy of sunlight, consistent with ab initio calculations, thus making it preferable for the solar selective absorber. We also discuss effects of the sample quality on the spectral reflectance.