Preparation and thermal stability of silica layer multicoated γ-Ce2S3 red pigment microparticles

The core-shell structured silica layer multicoated γ-Ce2S3 red pigment microparticles (γ-Ce2S3@SiO2 MPs) were prepared by the sol-gel process based on the Stöber method using tetraethoxysilane (TEOS) as silicon source and ammonium water as catalyst. The results demonstrated that the shell thickness and microporosity could be tuned by times of coating process. Different shell thickness of γ-Ce2S3@SiO2 MPs were uniformly formed with the shell thickness of 70 nm, 100 nm and 140 nm for once, twice and thrice coating processes. Particularly, the obtained γ-Ce2S3@SiO2 MPs with shell thickness of 140 nm showed excellent thermal stability in air at 570 °C and good stability in frit glaze at 620 °C while the steady temperature of pure γ-Ce2S3 is 350 °C. Such a core -shell configuration provided great protection for the γ-Ce2S3 pigment cores and made it as a potential substitute for toxic inorganic pigments.