New red-shade environmental-friendly multifunctional pigment based on Tb and Fe doped Y2Zr2O7 for ceramic applications and cool roof coatings

Abstract

A new red-shade environmental friendly ceramic pigment with the general formula Y2−xTbxZr2−yFeyO7−δ [x = 0, 0.25 and y = 0.15, 0.25, 0.35] was prepared by a polymeric sol-gel process and after calcination at 1300 °C for 12 h. The solid solution range with defect fluorite structure was determined by XRD. The presence of terbium ions promoted the incorporation of iron ions in the structure. The evolution of the colour was studied by UV/Vis absorption measurements and CIELab chromatic coordinates were determined. The colour was related to the oxidation states of the terbium and iron ions studied by XPS and photoluminescence. Pigments presented the best chromatic coordinates when the amount of Fe(III) and Tb(IV) ions were higher. The sample with good red colouration (x = 0.25, y = 0.35) was tested with an industrial frit, presenting slightly better chromatic coordinates to those of the commercial ceramic pigment currently used. The pigment also showed an optimal NIR reflectance to be applied as “cool pigment” for roof isolation.