H.R Hedayati - Faculty of Polymer Engineering & Color Technology, Amirkabir University of Technology, Tehran, Iran- Color and Polymer Research Center (CPRC), Amirkabir University of Technology, Tehran, Iran
A.A Sabbagh Alvani - Color and Polymer Research Center (CPRC), Amirkabir University of Technology, Tehran, Iran
H Sameie - Color and Polymer Research Center (CPRC), Amirkabir University of Technology, Tehran, Iran
S Moosakhani - Faculty of Polymer Engineering & Color Technology, Amirkabir University of Technology, Tehran, Iran- Color and Polymer Research Center (CPRC), Amirkabir University of Technology, Tehran, Iran

NIR reflective pigments are the group of pigments which reflect the wavelengths of incident electromagnetic radiationin the infrared region in addition to absorb visible light selectively leading to reduce heat build-up and maintain theaesthetic look of an object. The most important strategy for NIR reflective coating production is the formulation withcomplex inorganic colored pigments (CICPs). In the present study, nano-sized CoCr2O4 with impressive near infrared(NIR) reflectance (R*=43%) was synthesized via Pechini method. The developed nano-crystalline powders werecharacterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS) analysis,UV-vis-NIR diffuse reflectance spectroscopy and CIE-L*a*b* 1976 color scales. The results were compared withmicron-sized CoCr2O4 obtained by conventional solid-state method. According to UV-Vis-NIR spectrophotometry, thenano-sized pigment was found to possess higher NIR reflectance value and this can be attributed to their smaller meanparticle size and homogenous grains with detectable boundary lines which was in accordance with SEM and DLS results.In addition, nano-sized pigments are more interested because of better dispersion, color strength and other opticalproperties.

NIR reflective pigments, Pechini route, Solid-state method, UV-Vis-NIR spectrophotometry