Pink NIR Pigment Based on Cr-doped SrSnO3: Preparation and Characterization

Abstract

Perovskite pigments with SrCrxSn1-xO3-δ (x = 0.025, 0.05, 0.1, 0.2, 0.3) composition were prepared by a solid-state reaction, suspension mixing of materials and mechanochemical activation of initial reagents with calcination at high temperature. Results of thermal analysis show the effectivity of mechanochemical activation of reaction mixture that shifts the reaction course to lower temperature. Solid solution of SrSn0.975Cr0.025O3-δ was prepared at temperature 1200 °C. The optimal composition for synthesis of the intense red-pink powder is SrSn0.975Cr0.025O3-δ (L*/a*/b* = 36.34/14.21./1.12). Red-pink colour of the pigments is explained in terms of crystal field theory. The partial substitution of tin ions by chromium ions leads to the formation of the optical absorption bands corresponding to the O2p-Cr3d charge transfer transitions. Pigment is distinguished by good chemical stability in a molten ceramic glaze and high value of solar reflectance in the near-infrared region of light (R* approximate to 61%).