Sustainable inorganic pigments with high near-infra-red reflectance based on Fe3+ doped YAlO3 for high temperature applications

Non-toxic inorganic pigments based on the Fe(III)-doped YAlO3 with high near-infra-red (NIR) reflectance were synthesized by a modified Pechini method at 1200 °C. A complete solid solution in the YAl1−xFexO3 system (0 ≤x ≤ 1) was prepared, yielding a wide range of colourations from yellow to red, depending on the iron content. Good pigment stability was achieved in a commercial high temperature glaze, used in the ceramic industry to colour glazes on tiles. The pieces coated with the pigmented glazes reached NIR solar reflectance values between 43% and 32%. The temperature protection studies carried out with the glazes pigmented with YAl0.75Fe0.25O3 and YFeO3 compositions, conclude that the pigmented samples reduce the temperature of a building by 5 °C and 4 °C, respectively, in comparison to the unpigmented glaze. Thus, these pigments can be excellent candidates for used in high-temperature applications such as colouring ceramic high temperatures glazes, as well as cool pigments in walls or roofs of buildings.