Optical properties of bulk high-entropy diborides for solar energy applications

So far, the studies regarding innovative High-Entropy Borides (HEBs), which belong to more general class of Ultra-high temperature ceramics (UHTCs), have been entirely confined their fabrication or characterization from microstructural, mechanical and oxidation resistance viewpoints. In this work, optical properties two members HEBs, i.e. (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2 (Hf0.2Nb0.2Ta0.2Mo0.2Ti0.2)B2, are evaluated for first time assess possible utilization in thermal solar energy field. The bulk samples (96.5 % 97.4 dense, respectively) obtained as single-phase products by Spark Plasma Sintering (1950 °C/20 min/20 MPa) starting powders previously synthesized Self-propagating High-temperature Synthesis (SHS). characterization, whose results discussed comparing HEBs individual borides, shows that they characterized intrinsic spectral selectivity low emittance, resulting therefore interesting high-temperature absorbers applications.