Surface-modified Sm_0.5Sr_0.5CoO₃ by magnetron-sputtering and atmospheric treatments for spectrally selective applications

We investigated the optical properties of CuO-modified Sm_0.5Sr_0.5CoO_3-δ ceramics as possible candidate materials for solar absorbing applications. Bulk composite materials were successfully prepared by a facile and cost-effective solid-state reaction method and subsequent magnetron sputtering. The solar absorbance and spectral selectivity properties were evaluated using room-temperature hemispherical reflectance spectra measured from the ultraviolet to the mid-infrared region for samples with different composition, thickness, and surface roughness. The effect of annealing at different temperatures in air or oxygen was also investigated. The experimental results showed that a composite of Sm_0.5Sr_0.5CoO₃ and Cu (100 nm) ceramic annealed at 600 °C in air for 1 h had a solar absorbance comparable to that of the most advanced solar absorber materials, such as silicon carbide, with a higher spectral selectivity. Our material also exhibits better solar-selective absorption properties and higher solar selectivity (2.69) than that of smooth, unmodified Sm_0.5Sr_0.5CoO₃ (2.07) and could potentially be used as an alternative material for spectrally selective absorber applications.