Highly solar radiation reflective Cr₂O₃-3TiO ₂ orange nanopigment prepared by a polymer-pyrolysis method

The present study reports the preparation and characterization of an orange nanopigment with high solar radiation reflective properties. Complex Cr ₂O₃-3TiO₂ nanoparticles were prepared by the pyrolysis of Cr-Ti precursors at high temperature, and the effects of the calcination temperature on the structure of Cr₂O₃- 3TiO₂ nanopigment were investigated by thermal analysis, X-ray diffraction, and transmission electron microscopy. The results reveal that the Cr₂O - 3TiO₂ pigments having rutile structure can be prepared by the calcination of the precursor at above 600 C. All Cr ₂O₃-3TiO₂ pigments are granular in nature and present a homogeneous particle size of around 20 nm. The ultraviolet-visible near infrared (UV-vis-NIR) reflection spectra show that the Cr₂O ₃-3TiO₂ nanopigments have a reflection peak at around 600 nm, which reflects the orange color of these pigments. The average reflectance of Cr₂O₃-3TiO₂ in the NIR range is around 53%, respectively, which is much higher than that of the visible light range. The prepared orange Cr₂O₃-3TiO₂ nanopigments have a great potential in applications such as cool materials used for buildings with energy saving performance.