Research On Preparation And Near-Infrared Reflection Properties Of Doped-TiO₂ Energy-Saving Pigment

Near infrared reflecting doping pigments have been synthesized by sol-gel method.The crystal structure,near-infrared?NIR?reflectance,thermal stability and Lab value of the product were characterized by XRD,UV-vis-NIR,TG-DSC,XPS and chromaticity test.Finally,we mixed the pigments with acrylic resin and obtained the corresponding coatings.The thermal insulation performance of coatings were tested.The results are as follows:?1?The XRD diffraction and X-ray photoelectron spectroscopy and chemical stability analysis demonstrated the doping ions?Fe,Co,Ce?doped into the TiO₂ lattice.The XRD diffraction demonstrated that the crystal structure of TiO₂ did not change with different ion?Fe,Co,Ce?added.XPS demonstrated that Ti2p_1/2,Ti2p_3/2 and metallic oxide(O^2-)binding energy of TiO₂ were changed after doping.The color properties of pigments were not change after acid/alkali tests.This results also indicated the doping ions?Fe,Co,Ce?doped into the TiO₂lattice.?2?The color properties of pigments were changed by doping different ions?Fe,Co,Ce?into the crystal of TiO₂.When the concentration of Fe³⁺increased?x from 0.03 to 0.1?,the color of powder pigments change from orange yellow to iron red to light red,the near-infrared reflectance decreased from 74.06%to 62.99%and the band gap decreased from 3.0ev to 2.40ev.When the concentration of Co³⁺increased?x from 0.03 to 0.1?,the color of powder pigments change from light green to green,the near-infrared reflectance decreased from 77.78%to 67.07%and the band gap decreased from 3.0ev to 2.69ev.When the concentration of Ce⁴⁺increased?x from 0.03 to 0.1?,the color of powder pigments change from light yellow to yellow to light yellow,the near-infrared reflectance decreased from 94.57%to 90.94%and the band gap decreased from 3.0ev to 2.85ev.When the concentration of doping ions?Fe,Co,Ce?increased,the band gap and the near-infrared reflectance will decreased.?3?In addition,we mixed the pigments with acrylic resin and obtained the corresponding coatings.We have investigated the back temperature differences of pigment coatings used as building roof materials.Results showed that the near-infrared reflectance of Ti_0.95Fe_0.05O₂ is57.85%,and the temperature of Ti_0.95Fe_0.05O₂ coating is 8.9?lower than that of the commercial pigment coating;The near-infrared reflectance of Ti_0.95Co_0.05O₂ is 68.36%,and the temperature of Ti_0.95Co_0.05O₂ coating is 13?lower than of that the commercial pigment coating;The near-infrared reflectance of Ti_0.95Ce_0.05O₂ is 85.53%,and the temperature of Ti_0.95Ce_0.05O₂ coating is 6.7?lower than that of the commercial pigment coating.In conclusion,the doped TiO₂ pigments prepared by sol-gel method have good color properties and have good near-infrared reflectance.They could be new potential candidates for cool pigments in hot summer.