Effect of Firing Temperature and Mo Doping on the Synthesis of Solar-Reflective Sm₂Ce₂O₇ Yellow Pigment

Abstract:

Solar-reflective yellow pigment was synthesized by a solid-state reaction of the Sm₂O₃ and CeO₂ in the presence of the (NH₄)₆Mo₇O₂₄ employed for the Mo doping. The raw materials were wet milled in acetone for 6 h to acheive a homogeneous slurry followed by calcination at 1100, 1300 and 1500 °C for 6 h. The effect of the Mo doping was investigated by adding 10, 15, 20, 25 and 30 wt.% (NH₄)₆Mo₇O₂₄. XRD analysis of the undoped product revealed the formation of Sm₂Ce₂O₇ at 1300 °C along with the unreacted Sm₂O₃ and CeO₂, and revealed the completed reaction at 1500 °C. The addition of (NH₄)₆Mo₇O₂₄ resulted in the formation of Sm₂Ce_2-xMo_xO_7+δ, where x = 0.02, 0.03, 0.04 and 0.05 depending on the amount of the Mo dopant employed. The doping also significantly affected the product’s color; it turned from ivory white to yellow with the increase of dopant content up to 20 wt.% and became dark green afterward. Increasing firing temperature from 1100 to 1500 °C led to brighter yellow due to the substitution of Mo⁶⁺ for Ce⁴⁺. At the optimum synthesis condition, i.e. 20 wt.% doping and 1500 °C firing temperature, the product was most yellowish and had 69.2 % near-infrared reflectance.

• Periodical: Key Engineering Materials (Volume 659)
• Pages: 175-179
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.659.175
• Online since: August 2015
• Authors: Mantana Suwan, Pantip Sakchaikul, Sorachon Yoriya, Sitthisuntorn Supothina*
• Keywords: Cool Pigment, Near-Infrared Reflectance, Solar-Reflective Pigment, Yellow Pigment

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