Synthesis of near infrared-reflective Mo-doped Sm2Ce2 O7 yellow pigment and near infrared-reflective glazes

Abstract

Near infrared (NIR)-reflective Mo-doped Sm2Ce2O7 yellow pigment was synthesized by solid-state reaction of the Sm2O3 andCeO2 in the presence of the (NH4)6Mo7O24. All the raw materials were wet-milled in acetone for 6 hrs to achieve thehomogeneous slurry followed by drying and firing at 1100, 1300 and 1500 oC for 6 hrs. The effect of Mo doping wasinvestigated by adding 10, 15, 20, 25 and 30 wt.% (NH4)6Mo7O24 with respect to the CeO2. Extended X-ray absorption finestructure (EXAFS) analysis revealed the substitution of the Mo6+ for the Ce4+. The doping resulted in a change of product’scolor; it turned from ivory white to yellow with the increase of dopant content up to 20 wt.%, and became dark green at higherdoping level. With the increase of firing temperature from 1100 oC to 1500 oC, the color became brighter yellow due to moresubstitution of the Mo6+ for the Ce4+. At the optimum synthesis condition, i.e. 20 wt.% doping level and 1500 oC firing, theproduct was most yellowish and had 69.2% NIR reflectance. This NIR-reflective pigment was mixed with a traditional glazeand waste-derived glaze. The resultant NIR-reflective glazes had very good chemical resistance with good appearance. TheNIR reflectance increased from 50.7 to 59.7% for the traditional ceramic glaze, and from 31.5 to 42.3% for the waste-derivedglaze.