Novel Environmentally Friendly Inorganic Yellow Pigments Based on SnNb<sub>2</sub>O<sub>6</sub>

A novel environmentally friendly inorganic yellow pigment, Sn(Nb1－xGax)2O6－δ (0 ≤ x ≤ 0.10), was synthesized, and its optical and color properties were investigated. By doping Ga3+ into the Nb5+ sites of the SnNb2O6 solid, both the wavelength shift of the bandgap transition absorption and the change in the particle morphology were achieved. The reflectance in the visible light region was controlled －the reflectance in the green region was decreased and the yellowness was improved. As a result, the Sn(Nb0.99Ga0.01)2O6－δ showed a pure-yellow color with a yellowness value (b＊) of 90.0 and a hue angle (H°) of 90.6; these values are higher than those of the commercially available environmentally friendly BiVO4 pigment (greenish yellow, b＊＝76.9, H°＝77.8).