A new series of environment-friendly reddish inorganic pigments based on AFeO3 (A = Ln, Y) with high NIR solar reflectance

Abstract

Environment-friendly pigments based onAFeO3(A¼La, Pr, Nd, Sm, Gd, Tb, Y or Yb) with high near-infrared (NIR) reflectance were synthesised by a coprecipitation method at 1200 C. The Rietveldrefinement analysis showed single-phase orthorhombic perovskite for all compositions. All pigments,which showed reddish hues, offered good colour stability after mixing these pigments in powder formwith siloxane transparent paint and two different glazes. The powderepaint mixtures produced withGdFeO3, TbFeO3and YFeO3pigments have the highest NIR solar reflectance, reaching values ofR¼50%.The temperature shielding studies conducted using TbFeO3pigmentepaint mixture for a roof coatingyielded a reduction of 3.2 C in comparison to a commercial pigment. Moreover, the glazes that werepigmented using GdFeO3, TbFeO3and YFeO3compositions also presented the most intense reddishcolours. A study of the thermal and chemical stability of the pigment with the highest NIR solarreflectance showed good stability in both cases. The reddish pigments that were prepared can thereforebe good candidates for use in different applications such as cool pigments or pigments for ceramic glazesat high temperatures.