New environmental-friendly yellow pigments Y4–xAxMoO9+δ (A =Ta, Tb)

A series of inorganic yellow pigments with general formula Y4–xAxMoO9+δ (A = Ta, Tb), where x = 0, 0.05, 0.1, 0.2, 0.4 for Ta and x = 0, 0.005, 0.01, 0.03, 0.05 for Tb, were synthesized by a conventional ceramic method at 1400 °C for 6 h in air. The samples were characterized by XRD, EDS, XPS, SEM, TG-DSC, UV-vis-NIR reflectance spectroscopy and CIE L*a*b* color scales. It is found that the substitution of A (A = Ta, Tb) for Y3+ in Y4MoO9 decreases the NIR reflectance of the pigment samples, but the developed pigments Y4–xAxMoO9+δ (A = Ta, Tb) still exhibit impressive NIR solar reflectance. The brighter yellow color of inorganic pigments Y4–xAxMoO9+δ (A = Ta, Tb) is available when x is about 0.1 for Ta and 0.01 for Tb. The results make them a series of potential candidates as ecological yellow pigments because of their high reflectance, lightness, intense coloration and excellent thermal and chemical stability.