Lanthanum cobaltite black pigments with perovskite structure

•Black pigments with stoichiometry La1−xCaxCoO3 were obtained by the Pechini method.•The dark color was obtained with the use of only one transition metal.•Substitution of Ca for La did not influence pigment color but decreased its cost.

In this work La1−xCaxCoO3 (x = 0–0.4) pigments were synthesized by the polymeric precursor method with heat treatments at 700, 800 and 900 °C for 4 h. The powders were characterized by colorimetry, UV–vis spectroscopy and powder X-ray diffraction (XRD). The X-ray diffraction patterns showed the presence of a single phase perovskite, changing its structure from rhombohedral to cubic, when calcium was added to the lattice. All of the pigments had a black colour with a strong absorption over the whole of the visible spectrum as a consequence of the different oxidation states of cobalt and the high short-range disorder. The substitution of Ca2+ for La3+ did not influence the pigment colour but decreased its final cost.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide