Functionalization of SiC-based materials by a selective YBa2Cu3O7-δ coating via sol–gel route in order to optimize their optical properties

• A highly pure YBa2Cu3O7-δ oxide can be synthesized using sol–gel method.
• YBa2Cu3O7-δ oxygen stoichiometry and microstructure act on the spectral selectivity.
• Homogenous YBa2Cu3O7-δ coating is obtained on SiC substrate by dip-coating.
• The YBa2Cu3O7-δ film selectivity can be improved by decreasing its surface roughness.

SiC-based materials are good candidates for the application as solar receivers except concerning their optical properties. Indeed, considering the use at high temperature, materials used as solar receivers have to efficiently absorb the visible-near infrared waves (corresponding to solar spectral range) and simultaneously reflect the mid and far-infrared rays but SiC is absorbent in all the whole visible-infrared spectral domain. In this challenging work, a suitable YBa2Cu3O7-δ oxide which can present appropriate optical properties is studied. It was synthesized following a sol–gel route and it was obtained with a high level of purity. YBa2Cu3O7-δ pellets were realized and heat treated at different temperatures revealing that the higher the heat treatment is, the better the oxygen stoichiometry (7-δ) is and the smoothest the surface is. This directly acts on the YBa2Cu3O7-δ optical properties. Considering these results, an YBa2Cu3O7-δ coating was realized on SiC pellets by dip-coating. A homogenous and covering layer of about 10 μm was obtained presenting very promising optical properties which were predominant in the FIR-MIR range whereas absorptance was increased in NIR-visible range.