Synthesis and Optical Properties Based on Ni-Doped Zn2SiO4 Blue Pigments with High-NIR Reflectance

The severe urban heat island effect emphasizes the heightened importance of reducing building energy consumption. Cool pigments with higher near-infrared reflectivity contribute to the overall coating performance of the building. In this work, a novel intense blue pigment with superior infrared reflectance based on Ni-doped Zn2SiO4 was successfully synthesized via the simple solid-state method. The crystal structure, oxidation states, and optical properties are analyzed. The oxidation state of Ni was confirmed to be +2 using magnetic analysis and XPS. The intense blue color exhibited by the solid solution is due to the 3T1(3F) → 3T1(3P) transition of Ni2+ at the tetrahedral sites. UV–vis–NIR spectra demonstrate that this pigment exhibits superior near-infrared reflectance compared to cobalt blue in the range of 900–1700 nm, indicating its potential application in the realm of building energy conservation.