Synthesis and properties of novel turquoise-green pigments based on BaAl2-xMnxO4+y

BaAl2-xMnxO4+y (0 ≤ x ≤ 0.10) showing intense turquoise to green colors were prepared by the sol-gel method from metal nitrides as precursors and followed by a thermal treatment at 900 °C. The X-ray diffraction of all of the as-synthesized samples are indexed with BaAl2O4 stuffed tridymite structure. The oxidation state of Mn is confirmed to be +5 by X-ray photoelectron spectroscopy analysis. The colors of the samples are tuned to intense turquoise and green with the increase of Mn content. The optical properties are characterized by UV-Vis absorbance spectra and CIE L∗a∗b∗ coordinates. The reason for the intense colors is due to the Mn5+ doping in the [AlO4] tetrahedral sites. The pigments are applied to poly(methyl methacrylate) (PMMA) and the colours of the polymer composite were characterized.