High near-infrared reflection characteristics and energy-saving applications of Bi-doped LaAlO₃ perovskite yellow pigment

To expand the application of traditional pigments in the field of energy conservation and environmental protection, high NIR-reflective La_1−xBi_xAlO₃ (x = 0, 0.1, 0.15, 0.2, 0.25) yellow pigments with perovskite structure were prepared by wet ball milling combined with the high temperature solid phase method. The synthesized pigments were analyzed and evaluated using powder X-ray diffraction, Raman spectroscopy, CIE 1976 L* a* b* color, and UV–Vis-NIR spectrophotometry standard. The research results indicate that La_1−xBi_xAlO₃ pigment doped with Bi³⁺ has a wider absorption band in the blue purple region, and as the amount of Bi³⁺ doping increases, the pigment gradually changes from white to yellow. When the doping amount of Bi is 0.15, La_0.85Bi_0.15AlO₃ pigment shows particularly interesting results, good yellow color rendering effect and color saturation (L* = 70.72, a* = 5.08, b* = 43.79, c* = 44.09), especially, the pigment has a high near-infrared solar reflectance (R*) of 92.05 % and a high near-infrared reflectance of 98.95 %. La_0.85Bi_0.15AlO₃ pigment has superior thermal insulation performance as a thermal insulation coating, and the pigment can maintain structural stability at high temperatures. EnergyPlus simulations show that for southern cities with more heat and less cold (Haikou, Guangzhou), the La_0.85Bi_0.15AlO₃ coating used for the exterior surface of the model house can reduce the cooling energy consumption of the house. As a high near-infrared reflective material, it has good application prospects in the field of energy conservation and environmental protection.