The brown pigment with high near-infrared reflection based on Pr-doped Bi7.38Zr0.62O12.31

In this article, the novel environment-friendly brown near-infrared reflective pigments, Bi 7.38-x Pr x Zr 0.62 O 12.31+δ (x = 0-0.2), were synthesized via a high-temperature solid-phase reaction at 800 °C for 2 h. X-ray diffractometer, field emission scanning electron microscopy, UV–Vis–NIR spectroscopy, L* a* b* color space system and a UV aging test chamber were used to characterize the phase structure, micromorphology, optical characteristics, color properties, and UV aging resistance of the synthesized pigments. The results reveal that doping Bi 7.38 Zr 0.62 O 12.31 with Pr 6 O 11 caused a color transition from orange to brown. At a Pr doping level of 0.05, the brown pigment demonstrated a near-infrared reflectance of 96.54% and a near-infrared solar reflectance of 84.51%. Acid-base tolerance and UV aging tests showed that the color difference (ΔE*) between the pigments before and after treatment was less than 5, confirming its excellent stability. In the study of coating performance, air temperature inside the model coated with Bi 7.33 Pr 0.05 Zr 0.62 O 12.31 pigment was significantly lower than that of the model covered with commercial iron brown pigment after 90 min of infrared exposure. The temperature difference between the two models reaching 9.8 °C indicates that the prepared pigment had high near-infrared reflectance, which can effectively reflect solar thermal radiation and reduce heat absorption. It demonstrates potential for application in building energy efficiency and environmental sustainability.