Novel environment-friendly inorganic red pigments based on (Bi, Er, Y, Fe)2O3 solid solutions

Novel environmental-friendly inorganic red pigments, ((Bi0.72Er0.28−xYx)1−yFey)2O3 (0 < x ≤ 0.28, y = 0.20), were successfully synthesized using a conventional solid-state reaction method in order to further enhance the red hue of a ((Bi0.72Er0.28)0.80Fe0.20)2O3 pigment, which was previously reported by our group. The color of the samples depended on their composition and the most brilliant red hue was obtained for ((Bi0.72Er0.04Y0.24)0.80Fe0.20)2O3. The a* value corresponding to red chromaticity was +33.1 for ((Bi0.72Er0.04Y0.24)0.80Fe0.20)2O3, and it was greater than those of previously reported ((Bi0.72Er0.28)0.80Fe0.20)2O3 (a* = +30.9) and commercial Fe2O3 (a* = +28.9) pigments. Since the ((Bi0.72Er0.04Y0.24)0.80Fe0.20)2O3 pigment is composed of nontoxic elements (Bi, Er, Y, Fe, and O), it should be an attractive alternative to the conventional Fe2O3 pigments.