Chemical defects confined in Tb-doped SrCeO3 yellow cool pigments for the enhanced color and solar reflective performances

The optical properties of colored cool pigments including their color and solar reflectance are predominantly governed by chemical defects.In this study, a series of yellow cool pigments SrCe 1-x Tb x O 3 (x = 0–0.3) and SrCe 0.7-x Tb 0.3 Y x O 3 (x = 0–0.1) were synthesized via the solid-state reaction based on defect engineering. The effects of chemical defects on their optical performance were systematically investigated. Tb doping extends the absorption edge of the pigments to the visible region beyond 500 nm, thereby imparting a distinct yellow hue to the pigment. However this doping process simultaneously introduces oxygen vacancy defects and facilitates the coexistence of mixed-valence cations (Ce 4+ /Ce 3+ and Tb 4+ /Tb 3+ ) within the host lattice. This results in pronounced tail absorption that compromises both color properties and solar reflectance. To address this issue, yttrium was introduced as a co-dopant following the charge compensation principle which effectively suppressed defect formation and reduced tail absorption intensity. This co-doping strategy successfully achieved a synergistic optimization of pigment color and solar reflectance. The optimized pigments exhibited a high b* value of 75 and an exceptional near-infrared reflectance of95.33 %. The simulation experiment revealed that coating based on the as-prepared pigment exhibited an internal surface temperature reduction of 15.5 °C compared to the conventional cement coating. These findings underscore that optimizing color and solar reflectance through chemical defect regulation represents a feasible approach for preparing high-performance colored cool pigments.