Enhanced optical reflectivity and electrical properties in perovskite functional ceramics by inhibiting oxygen vacancy formation

Perovskite functional ceramics have attracted considerable interest owing to their promising catalytic, optical and electrical performance. To understand the relationships between oxygen vacancy defects and the properties of perovskite materials through Nb⁵⁺ doping, new perovskite composite La_0.9Sr_0.1Ti_0.75Nb_0.25O_3+δ (LSTN_0.25) ceramics are proposed. These are synthesized by Nb₂O₅-doped La_0.9Sr_0.1TiO_3+δ and exhibit layered perovskite (La, Sr)₂(Ti, Nb)₂O₇ and scheelite LaNbO₄. Their microstructure, reflectivity, band structure, and dielectric properties were investigated through experiments and first-principles calculations. The energy calculations and electron paramagnetic resonance signals performed on oxygen vacancy suggested that oxygen vacancy defects are difficult to form and at a lower level in LSTN_0.25, which significantly improved the near-infrared reflectivity. The dielectric properties and band structure demonstrated that LSTN_0.25 sintered at 1400 °C exhibited higher reflectivity than those of the La_0.9Sr_0.1TiO_3+δ ceramics. These findings shed light on the role of Nb⁵⁺ in inhibiting oxygen vacancy formation in perovskite and provide an approach for fabricating novel, full-band, high reflectivity perovskite ceramics through high valence element doping.