Effect of Sr2+ and Dy3+ co-doping on coloration and temperature stabilization of a γ-Ce2S3 red pigment

Abstract

In this paper, a Sr2+and Dy3+co-doped γ-Ce2S3 red pigment was synthesized via a combination of coprecipitation and sulfurization processes. Mixed oxide was prepared by presintering the coprecipitates, (Ce,Sr,Dy)CO3, followed by high-temperature sulfurization under a CS2 atmosphere. The effects of the sulfurization temperature, time, and doped proportion on the phase composition, color performance and temperature stability of γ-Ce2S3 were systematically studied. The results show that a stable γ-Ce2S3 red pigment can be obtained through Sr2+ and Dy3+ co-doping at 730 °C for 200 min. The diffraction peaks of all the samples shift to higher 2θ values with increasing doping proportion, indicating that part of the Dy3+ species enter the lattice and form a solid solution. The band gap of the samples remains practically constant at 2.01–2.04 eV, which causes their red color. The best red-color quality (L* = 37.13, a* = 34.77, b* = 29.44) is achieved when the pigment has a Dy3+/Ce3+ molar ratio of 0.15, and the material maintains its excellent red color (L* = 31.49, a* = 30.94, b* = 25.33) after being heated at 410 °C for 30 min.