No abstract

Novel inorganic red pigments based on bismuth oxide, [(Bi1−xErx)1−yFey]2O3 (0 < x ≤ 0.50, 0 < y ≤ 0.30), were synthesized by a conventional solid-state reaction method, and their color properties were characterized. The color of the sample depended on its composition, with the [(Bi0.72Er0.28)0.80Fe0.20]2O3 pigment having the most vivid red hue. The a* value corresponding to red chromaticity of the [(Bi0.72Er0.28)0.80Fe0.20]2O3 pigment was +30.9, which was greater than that of a commercial Fe2O3 pigment (a* = +28.9). Since these pigments are composed of nontoxic and safe elements, they can be effective alternatives to the conventional Fe2O3 pigment.

Novel inorganic yellow pigments, Bi 1ÀxÀyÀz Ca x Zn y La z VO 4À(x+y)/2 (0.04 # x # 0.12; 0.01 # y # 0.05; 0.01 # z # 0.10) were synthesized as environmentally friendly inorganic materials, and their color properties were characterized. All the pigments exhibited brilliant yellow colors, and using the CIE L*a*b* system, the most vivid yellow hue was obtained for Bi 0.85 Ca 0.08 Zn 0.02 La 0.05 VO 3.950 with a yellowness value (b*) of +93.5, which is much greater than that of a commercially available BiVO 4 pigment (b* ¼ +76.9). Since BiVO 4 is an environmentally friendly inorganic yellow pigment, and Ca, Zn, and La are also nontoxic and safe elements, the Bi 0.85 Ca 0.08 Zn 0.02 La 0.05 VO 3.950 pigment could be an effective alternative to conventional toxic yellow pigments.

a b s t r a c t Novel environmental-friendly inorganic red pigments, ((Bi 0.72 Er 0.28−x Y x ) 1−y Fe y ) 2 O 3 (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 ((Bi 0.72 Er 0.28 ) 0.80 Fe 0.20 ) 2 O 3 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 ((Bi 0.72 Er 0.04 Y 0.24 ) 0.80 Fe 0.20 ) 2 O 3 . The a* value corresponding to red chromaticity was +33.1 for ((Bi 0.72 Er 0.04 Y 0.24 ) 0.80 Fe 0.20 ) 2 O 3 , and it was greater than those of previously reported ((Bi 0.72 Er 0.28 ) 0.80 Fe 0.20 ) 2 O 3 (a* = +30.9) and commercial Fe 2 O 3 (a* = +28.9) pigments. Since the ((Bi 0.72 Er 0.04 Y 0.24 ) 0.80 Fe 0.20 ) 2 O 3 pigment is composed of nontoxic elements (Bi, Er, Y, Fe, and O), it should be an attractive alternative to the conventional Fe 2 O 3 pigments.

Novel environment friendly inorganic red pigments, (Bi 1ÀxÀy Zr x Al y ) 4 V 2 O 11+d (0 # x # 0.15; 0 # y # 0.10), were successfully synthesized by a conventional solid state reaction method, and their colour properties were characterized. The colour of the obtained pigments was dependent on the calcination condition and the sample composition, and the highest red hue was obtained for the (Bi 0.92 Zr 0.07 Al 0.01 ) 4 V 2 O 11.34 pigment calcined at 800 C for 10 h in a flow of pure O 2 . The a* value corresponding to the red chromaticity of this pigment was +41.9, which was significantly greater than that of the commercial iron oxide pigment (a* ¼ +28.9). Bi 4 V 2 O 11 is considered to be a nontoxic compound, and the other components (Zr and Al) are also safe elements. Therefore, the present pigment could be an attractive candidate as a novel environment friendly inorganic red pigment.