Synthesis and characterisation of SrYCeO as environmentally friendly reddish-brown pigments

Reddish-brown SrY 2− x Ce x O 4 (0 ≤ x ≤ 1.2) solid solutions were synthesized by a citrate sol-gel method as novel environmentally friendly inorganic pigments. The powders obtained were characterized by X-ray powder diffraction (XRD), UV-vis diffuse reflectance spectra and CIE L * a * b * Ch ° chromatic coordinate measurements. All SrY 2− x Ce x O 4 (0 ≤ x ≤ 1.2) samples were obtained in a single-phase form and the lattice volume increased on increasing the Ce 3+ concentration. The reddish-brown pigments exhibited optical absorption due to the 4f-5d allowed transition of Ce 3+ . The absorption bands observed in the wavelength region of 400 and 550 nm were due to the Ce 3+ ions in the ideal octahedral Y 3+ site and those in the longer wavelength region above 600 nm were attributed to the transition of Ce 3+ in the distorted octahedral Y 3+ site. The samples gradually became reddish on increasing the Ce 3+ content. The most reddish colour was obtained in SrYCeO 4 ( a * = +21.8). SrY 2− x Ce x O 4 solid solutions were synthesized as environmentally-friendly inorganic pigments and the color gradually changed from yellow to reddish brown on increasing the Ce 3+ concentration.