Colour possibilities of rare earth orthoferrite pigments

Abstract

The paper deals with the preparation of the inorganic pigments of general formula RE0.98Ca0.02FeO3, where RE = La, Gd, Lu, Tm, Yb and Ho. The pigments were prepared by the conventional ceramic method, i.e. solid state reaction. As initial components were used Ln2O3, CaCO3 and two sources of Fe components, either Fe2O3 or FeOOH. The reaction mixtures were heated at the temperatures of 800, 900 and 1000 °C. The prepared pigments were applied to an organic binding system and their colour properties evaluated by measuring reflectance in the visible region of light. The most interesting colour properties were obtained by the preparation of the sample Lu0.98Ca0.02FeO3. This pigment was prepared by the calcination of the reaction mixture containing FeOOH and mineralizer LiF at the temperature of 900 °C. Generally, the mineralizer LiF affects the colour properties of all the pigments most significantly.