Chromatic and near-infrared reflective properties of Fe3+ doped KZnPO4

This paper adopted the coprecipitation method to prepare a new-type inorganic pigment KZn1−x(Fe)xPO4 (x = 0.00, 0.05, 0.10, 0.15) with high near-infrared reflective properties. The reflective properties and structure of the product were investigated by UV-vis-NIR spectrophotometer and XRD. Results showed that after doping with Fe3+, the crystal structure of KZnPO4 did not change; while the color of the sample deepened with the increasing concentration of Fe3+ (x = 0.05-0.15), the band gap decreased from 2.00 eV to 1.95 eV, and the near-infrared reflectance reduced from 74.7% to 67.1%. For the aluminum sheet coated with KZn0.9(Fe)0.1PO4 pigment, with coating thickness of 312 μm, the near-infrared reflectance could reach 46.7%, higher than the reflectance of conventional pigment of similar color (32.1%). Therefore, the prepared KZn1−x(Fe)xPO4 pigments can be well served as “cool colorant”.