Sustainable cool pigments based on iron and tungsten co-doped lanthanum cerium oxide with high NIR reflectance for energy saving

The novel non-toxic yellow-orange inorganic pigments La2Ce2-xW0.5xFe0.5xO7+delta (x = 0.1, 0.3, 0.5, 0.7, 0.9) with high near-infrared reflectance have been synthesized. The crystal structure, chemical composition, optical properties (reflectance and absorption properties) and color performance of the synthesized pigments were characterized by several techniques. X-ray diffraction analysis indicated the disordered defect fluorite-type structure of the pigments. The typical pigment La2Ce1.5W0.25Fe0.25O7+delta possessed the high NIR solar reflectance of 82.05% with orange color (L* = 77.21, a* = 8.79, b* = 35.80). Also the influence of calcination temperature has been studied, the higher temperature resulted in enhanced color and slightly reduced reflectance properties. The applicability of typical pigment La2Ce1.7W0.7xFe0.15O7+delta (calcined at 1150 degrees C) was tested on a galvanized sheet, the coating improved the NIR solar reflectance from 19.18% to 71.07%. The acid/alkali resistance studies confirmed the pigments were chemically stable. Thus, the synthesized pigments with vivid yellow-orange color and high NIR reflectance have exhibited application potentials.