Novel orange-red glaze based on In-doped CaFe2O4 red chromophore: Synthesis, properties and characterizations

The CaFe 2- x In x O 4 (0 ≤ x ≤ 1) pigment with red shade was successfully synthesized through solid state reactions. The crystal structure, color development mechanism, morphology and its application in the glaze were studied. XPS analysis confirmed Fe resides in +3 oxidation state. Combined with UV-Vis-NIR analysis, it is determined that the formation of red shade of the pigment is due to the 6 A 1 (S) → 4 T 2 (D), 6 A 1 (S) → 4 A 1 , 4 E(G) and 6 A 1 (S) → 4 T 2 (G) transitions of Fe 3+ in the visible light region. The pigment was applied to the lead-free low temperature glaze to evaluate its potential in preparing new glaze color. The as-synthesized glaze showed orange-red shade. With increased In 3+ doping concentration, the glaze demonstrates a stronger red tone. The glaze also shows high NIR solar reflectance. Inferred from SEM-EDS, the pigment particles are evenly scattered in the glaze. Therefore, CaFe 2- x In x O 4 (0 ≤ x ≤ 1) red pigment is a qualified candidate for red shade glaze preparation.