Investigation on multifunctional binary oxides for near-infrared (NIR) reflective pigment applications

In this work, we have investigated the solar reflective and color pigmentation effectiveness of some multifunctional binary oxides, Nb2O5, Ta2O5, Gd2O3, Dy2O3, La2O3, Sb2O3, Cr2O3, Y2O3, SnO2, and MnO2 with the aid of XRD and diffuse reflectance spectroscopy (DRS) techniques. We have also reviewed the recent studies in NIR pigments of multifunctional oxides. From the obtained NIR reflectance values, we note that Gd2O3, Sb2O3, Ta2O5, Nb2O5, and Y2O3 showed interesting features on NIR reflectance on both the solar reflective (750-1350 nm) and color pigmentation region (1350-2500 nm). The oxides like SnO2 and La2O3 demonstrate relatively high solar reflective pigmentation (750-1350 nm) features than color pigmentation. MnO2 and Cr2O3 show low NIR reflectance both in solar and color pigmentation regions as compared to other types of oxides investigated in the present work. Among the different investigated oxides, Nb2O5 exhibits a relatively high NIR reflectance value (similar to 85%) in the NIR region (750-2500 nm). On the other hand, the MnO2 powder reveals the lowest NIR reflectance value (15-20%) in the NIR region. The UV-visible absorbance spectra and their energy bandgap of the different oxides have also been compared.

Automated summary

This study investigated the solar reflective and color pigmentation effectiveness of multifunctional binary oxides using XRD and DRS techniques. The results showed that Gd2O3, Sb2O3, Ta2O5, Nb2O5, and Y2O3 exhibited interesting features in the NIR region, while MnO2 and Cr2O3 had lower NIR reflectance.