Novel environment-friendly green pigments based on rare earth cuprate

Novel green pigments based on (R1-xR'x)2Cu2O5 (R = Y3+, R’ = Sc3+, Gd3+, Tm3+, Yb3+, and Lu3+) solid solutions were synthesized and the dopant concentration was optimized. Among the samples, it was found that Su2Cu2O5 based samples showed brilliant green hue. In response to the results, Sc2(Cu1−xZnx)2O5 (0 ≤ x ≤ 0.1) pigments were further synthesized and their color properties were characterized in an attempt to find a new environmentally friendly pigment that has more sufficient green chromaticity. Among the samples, the most vivid green hue was obtained for Sc2(Cu0.92Zn0.08)2O5 with a greenness value (−a*) of 41.2 in the CIE L*a*b* system, which was significantly larger than those of commercially available Cr2O3 (−a* = 18.2), CoO∙ZnO (−a* = 25.3), and Co2TiO4 (−a* = 35.2) pigments. Scandium, cupper, and zinc in Sc2(Cu0.92Zn0.08)2O5 are nontoxic elements; therefore, the pigment should be an effective alternative to the conventional toxic green pigments. [Display omitted] •Novel green pigments based on Su2Cu2O5 were synthesized.•The color properties of the samples were characterized using the CIE L*a*b*CH° system.•The most vivid green color was obtained for Sc2(Cu0.92Zn0.08)2O5.•The greenness value (−a*) of Sc2(Cu0.92Zn0.08)2O5 was 41.2.•Sc2(Cu0.92Zn0.08)2O5 is an environmentally friendly pigment.