Ce doped (Y, Yb)3Al5O12 yellow cool pigment with high solar reflectance and enhanced colour performance

Abstract

The high solar reflectance and good colour performance are requisite for the practical application of the colour-cool pigment. In this work, Ce-doped Yb3Al5O12 and (Y, Yb)3Al5O12 ceramic pigments were prepared by the sol-gel method. Both Ce3+ and Ce4+ ions coexist in the doped pigments. Due to the 4f→5d electron transition of Ce3+, the Ce-doped pigments have a selective absorption at around 400–520 nm, which is responsible for the yellow hue. The content of the Ce3+ ion determines the colour performance of the pigment. The size effect from the smaller Yb3+ ion results in an increased content of Ce3+ in the Ce-doped pigments, leading to an improved colour performance. The incorporation of Y3+ ion can effectively decrease the absorption at 975 nm, thereby enhancing the solar reflectance to 80.6 %, while maintaining good colour performance (Yb0.7Y2.1Ce0.2Al5O12, L* = 91.40, a* = -4.89, b* = 45.33). In a simulation experiment, the ceramic glaze coating based on the prepared pigment showed a temperature reduction of 5.2 °C compared to the commercial yellow pigment ceramic coating.