Synthesis and characterization of Fe3+doped YIn1-yMnyO3 black pigment with high near-infrared reflectance

Near infrared reflective inorganic pigment YIn1-x-yMnyFexO3 (x/y = 0.1-0.5) was prepared by solid state reaction. The X-ray diffraction analysis and CIE1976 L*a*b* colorimetric analysis reveal that the main phase of the sample is changed from YInO3 phase to YFeO3 phase and the color of the sample is changed from blue to black (x >= 0.4) with the increase of iron content. The brightness value of black pigment ranges from 23.27 to 32.12. When In3+ is replaced by Fe3+ and Mn3+, the band gap of the black sample is decreased from 1.73eV to 1.39eV. The near-infrared reflectance (R) and near-infrared solar reflectance (R*) of the sample reach the maximum when x = 0.4 and y = 0.1, which are 77.82% and 53.44%, respectively. YIn1-x-yMnyFexO3 (x = 0.4-0.5, y = 0.1-0.5) black samples have higher near infrared reflectivity than common commercial black pigments. In the thermal insulation study, under the condition of infrared irradiation for 90 min, the internal air temperature difference between the iron car model coated with YIn0.5Mn0.1Fe0.4O3 pigment and the iron car model coated with commercial iron black pigment can reach 7 degrees C. YIn0.5Mn0.1Fe0.4O3 black pigment was soaked in 5% acid-alkali solution for 24 h, the chromaticity was almost unchanged before and after immersion, indicating that the sample has good chemical stability. The above properties show the potential of synthetic black pigments in the field of energy conservation.