Solution combustion synthesis of gray-blue Mn-doped YBO3 pigments with high NIR reflectance for energy-saving buildings

High near-infrared (NIR) reflective pigments have broad application prospects in alleviating urban heat island effect. But in fact, an easy and efficient method of preparing non-toxic and high near-infrared reflective pigments remains a desired choice for energy-saving coatings. In this research, several Mn doped YBO3 pigments, pos-sessing gray-blue and high near-infrared reflectance, were effectively prepared by solution combustion method. Relevant techniques were used to characterize the crystalline structure, morphology feature, optical properties, chemical tolerance, and heat insulation effect of the prepared pigments. The results presented that the color of powders varied from white to gray-blue due to the Mn doping. The band gap energy increased from 2.03 eV to 2.14 eV as the doping amount raised, and it could be assigned to the charge transfer transition between O 2p valence bands and Mn 3d conduction bands. The typical YB0.97Mn0.03O3 pigment stated the excellent near -infrared reflectance of 66.18% and significant color properties (L* = 69.75, a* =-5.46, and b* =-6.36). Notably, the surface temperature of YB0.97Mn0.03O3 coating is 39.5 degrees C lower than the gray-blue commercial pigmented coating. This work demonstrated that the prepared pigments with rather high reflectance possessed potential application in energy-saving materials for buildings.