Synthesis, properties and applications of novel inorganic yellow pigments based on Ni-doped Al2TiO5

Single phase Al2-2xNixTi1+xO5 (0 ≤ x ≤ 0.4) solid solutions were successfully synthesized by solid-phase reaction. The color of the compounds varied from yellow (x = 0.1) to turmeric (x = 0.4) with increasing nickel content. X-ray photoelectron spectroscopy analysis confirmed that the oxidation state of Ni is +2. The UV–Vis absorption spectrum showed that the color of the sample comes from the d-d transition of Ni2+ in octahedral coordination. Owing to excellent high temperature stability, the as-prepared oxide powders (10 wt%) were mechanically mixing with Al2O3 by conventional ball milling to prepare colored alumina ceramics. When Al2O3 is in excess, the blue NiAl2O4 impurity phase appeared, contributing to an intense green color of the Al2O3 ceramics composite. The Vickers micro hardness value of green alumina was higher than that of pure white alumina. The as-prepared samples were also dispersed in PMMA and bright yellow polymer composites were obtained, indicating great potential in polymer colorant.