A new environmentally benign near-infrared reflectance pigment based on BiFeO₃ doped with La³⁺ was described. The pigments of the formula Bi_1-xLa_xFeO₃ (x = 0, 0.1, 0.2, 0.3, 0.4) were characterized by XRD, FE-SEM, TG-DTA, UV-vis-NIR spectrophotometer and CIE L^∗a^∗b^∗ color scales. The results reveal that the pigments crystallized at 600 °C with particle size less than 70 nm. The substitution of La³⁺ for Bi³⁺ in BiFeO₃ shift the color from dark brown to reddish brown and the band gap decrease from 2.24 to 2.03 eV due to O_2p-Fe_3d charge transfer transitions. The near-infrared solar reflectance of the powdered pigments increased with the increase of progressive doping of La³⁺ for Bi³⁺. The pigment coated on concrete cement substrate exhibit higher near-infrared solar reflectance (R^∗ ≥ 44.1%) than conventional coating of similar color. Moreover, the thermal and chemical stability of the pigments were also evaluated. In conclusion, the pigments have the potential to be applied as “cool pigments”.

描述了一种新的对环境友好的基于BiFeO _3的La ³⁺掺杂的近红外反射颜料。用XRD，FE-SEM，TG-DTA，UV-vis-NIR分光光度计和CIE L ^∗ a表征式Bi _1-x La _x FeO ₃（x = 0、0.1、0.2、0.3、0.4）的颜料^∗ b ^∗色标。结果表明，颜料在600°C时结晶，粒径小于70 nm。La ³⁺代替BiFeO _3中的Bi ³⁺导致颜色从深棕色变成红棕色，并且由于O _2p -Fe而使带隙从2.24 eV减小到2.03 eV_3d电荷转移过渡。随着La ³⁺对Bi ³⁺的逐步掺杂，粉末状颜料的近红外太阳反射率增加。颜料涂覆在混凝土水泥类基材具有更高的近红外日光反射（R ^* 不是相似的颜色的常规涂覆≥44.1％）。此外，还评估了颜料的热稳定性和化学稳定性。总之，这些颜料有潜力被用作“凉爽颜料”。