Specific features of spectral and electrical properties of double-perovskite LnBaCo2O5+δ (Ln=lanthanides) under solar irradiation

Cobalt-based perovskite oxides, LnBaCo2O5+δ (Ln=La to Lu), were investigated as potential variable electrical and thermal radiative materials under solar irradiation. The particular Ln3+ dopant has a significant effect on the oxide's phase structure, spectral reflectivity, electrical conductivity, and thermal radiative properties. Stable, cation-ordered oxides with layered lattice structures were obtained with medium-size Ln3+ ions. The general features of the electrical and spectral reflective properties of LnBaCo2O5+δ (Ln=La, Nd, Sm to Ho) are discussed. It is shown that LnBaCo2O5+δ (Ln=Sm to Ho) has a significant insulator-metal transition under solar irradiation, whereas LnBaCo2O5+δ (Ln=La, Nd) has a lower infrared emissivity at high temperatures due to the metal-like optical behavior.