Robust optical properties of Re_0.5Sr_0.5CoO_3−δ (Re = Nd, Eu, Gd) ceramics for high temperature solar absorber applications

The efficiency of concentrated solar power (CSP) systems depends highly on the operating temperature. Currently, challenge remains on developing a solar absorber that not only possesses good optical performance but also excellent thermal stability at high temperature in air. Herein, the optical properties of Re_0.5Sr_0.5CoO_3−δ (Re = Nd, Eu, Gd, ReSC-5) ceramics were investigated to evaluate their potential application as high temperature solar absorbers. Results showed that the reflectance spectra of ReSC-5 exhibited low reflectance values in the 0.3–2.5 μm wavelength range and high reflectance values in the wavelength range of 2.5–15 μm (infrared range). The spectral selectivity of ReSC-5 (2.3–2.9) is higher than that of SiC ceramic (1.0). Besides, the ReSC-5 ceramics showed low radiation temperature at high temperature and robust optical properties even underwent heat treatment at 800 °C for 9 h in air. These results suggest that the ReSC-5 ceramics are promising candidate for high temperature solar absorbers.