Highly dispersed (Cr, Sb)-co-doped rutile pigments of cool color with high near-infrared reflectance

• Pigments had regular morphology and narrow size distribution ranging from 0.5 to 1 μm.
• The pigments had high luminosity values and good color properties.
• Pigment showed homogeneous dispersion without any milling and sieving.
• Pigments had high NIR reflectance.
• The existence of Cr6+ would reduce significantly color properties and NIR reflectance.

Highly dispersed (Cr, Sb)-co-doped rutile nonwhite pigments with high near-infrared (NIR) reflectance were prepared by introducing dispersants during precursor hydrolysis. The pigment properties were investigated by X-ray diffraction, scanning electron microscopy, X-ray photoemission spectroscopy, diffuse reflectance spectroscopy, Raman spectroscopy, and colorimetry. The pigments had rutile phase composition and narrow size distributions of 0.5 μm–1 μm after calcination at 700 °C. Co-doping with Cr and Sb restrained the generation of hexavalent chromium in the rutile lattice. The co-doped pigments had good color properties and high NIR reflectance because of the absence of Cr6+. The pigments had high tinting strength, and a good hue for PE flake was attained by adding 1% pigments. An approximately 10 °C decrease in temperature was obtained for the inner surface of ceramic tiles coated with the co-doped pigments under 30 min of irradiance.