Preparation and Color Tuning of Ba2+-Sr2+ Co-Doped Γ-Ce2s3 Pigments

In this work, Ba2+-Sr2+ co-doped γ-Ce2S3 (γ-[Ba, Sr]-Ce2S3) pigments were synthesized by using a co-precipitation method with a composition of n (Ba)/n (Ce1-xSrx) = 0.1 (molar ratio, x = 0, 0.01, 0.03, 0.05, 0.10, 0.15, 0.20, 0.30, and 0.40 mol). The effect of the doping content of Sr2+ on vulcanization temperature, phase composition, band gap, chroma and temperature stability of γ-[Ba, Sr]-Ce2S3 pigments was systematically studied. The results show that a pure gamma phase γ-[Ba, Sr]-Ce2S3 can be obtained at 850 °C when x varied from 0 to 0.30. With increasing Sr2+ content, the band gap of γ-[Ba, Sr]-Ce2S3 increased from 2.016 to 2.258 eV, and thus the color of pigments had changed from red ((L* = 32.97, a* = 47.74, b* = 39.20 (x =0.00)) to orange (L* = 39.86, a* = 41.66, b* = 48.15 (x =0.15)) and then to yellow (L* = 51.28, a* = 30.83, b* = 58.30 (x = 0.30)), indicating that Ba2+-Sr2+co-doping can effectively tune the color of γ-Ce2S3. The temperature stability of γ-[Ba, Sr]-Ce2S3 pigments was also improved from 479.9 °C (x = 0) to 564.4 °C (x = 0.30).