Optical properties and thermal stability of La_1−xSr_xCoO_3−δ (0.2 ⩽ x ⩽ 0.8) ceramics

Perovskite-type La_1−xSr_xCoO_3−δ (0.2 ⩽ x ⩽ 0.8) ceramics were prepared by tape casting and solid state reaction method. The room temperature optical properties of these samples were studied in detail. The temperature dependent emittance measurements and high-temperature durability tests were carried out. Results showed that these materials exhibited low reflectance at the solar spectrum wavelengths and high reflectance in the infrared region, with an optimal spectral selectivity of 3.2. The investigated samples showed low thermal emittance at high temperatures. More importantly, the sample was highly stable in air at 800 °C, as the performance criterion value was lower than 0.05 after 10 cycles (90 h) heat treatment. Our results demonstrate that the La_1−xSr_xCoO_3−δ ceramics have the potential to emerge as high temperature (∼800 °C) solar absorbers for the future solar power systems.