Environmentally friendly orange pigments based on hexagonal perovskite-type compounds and their high NIR reflectivity

Novel environmentally friendly inorganic orange pigments based on the hexagonal perovskite-type pigment Sr4Mn2(Cu1-xZnx)O-9 (0 <= x <= 1) were synthesized and their optical and color properties were determined. Using Zn2+ doping (x = 0.5), the optical absorption caused by a ligand-metal charge transfer transition was reduced due to anisotropic lattice distortion, while the optical absorption corresponding to the d-d transition of Cu2+ was clearly observed at 670 nm. As a result, the Sr4Mn2(Cu0.5Zn0.5)O-9 sample possessed a brilliant orange color with L*, a*, b*, C, and H degrees values of 64.0, +19.8, +52.3, 55.9, and 69.3, respectively. In addition, the Sr4Mn2(Cu0.5Zn0.5)O-9 orange pigment also possessed outstanding NIR reflectance compared with the commercially available bayferrox orange 960, indicating the potential of this new pigment for use as an energy-saving material. (C) 2017 Elsevier Ltd. All rights reserved.