Papers by Author: Ewa Stobierska

Abstract: Double yttrium-aluminium oxide with perovskite structure (YAP) doped with chromium(III) ions seems to be a promising material for red pigments for new ceramic bodies and glazes. The aim of the present paper was to examine the influence of the precursors morphology on colour properties of the YAP pigments. Two kinds of aluminium hydroxide powders were used, fine- and coarse-grained. The fine Al(OH)3 powder was amorphous with D50=4.58 µm and the coarse one was crystalline gibbsite with D50=42.4 µm. It was stated that using of aluminium hydroxide powders of different morphology led to substantial differences in phase composition of the final materials. Using coarse-grained aluminium hydroxide powder caused formation of over 95 wt% of YAP phase whereas the pigments prepared with amorphous aluminium hydroxide contain significant amounts of other phases in the Y2O3-Al2O3 system. The differences in phase compositions resulted in differences in colour properties of the pigments.

Abstract: The results of preliminary investigation on preparation of perovskite pigments by solid state reaction are presented. The effects of different raw materials used as component carriers on formation of colored pigments were examined. Pigment composition, optimum chromophore addition, type of mineralizer and the conditions of synthesis were determined experimentally as well as the resulting color, phase composition and morphology of powders. The wet method of preparation of starting mixtures was also analyzed.