Synthesis and sintering of chemically derived BaO–ZrO2 solid solutions

Several zirconia–baria solid solutions were obtained by sintering powders produced by coprecipitation from solutions of zirconyl chloride hydrate and barium nitrate. The fired materials had monoclinic, cubic or tetragonal structure depending of composition which ranged from 4 to 16 mol% BaO. The pure cubic phase could be retained at room temperature for compositions from 10 to 12 whereas materials containing 16 mol% BaO were tetragonal; for lower baria content a mixture of monoclinic and cubic phase was detected. The double phased materials can be fully transformed into the monoclinic form by grinding while for pure cubic or tetragonal samples the transformation is not full. Samples fired at 1450 °C had coarse microstructures and the grains dimension is of several microns just after 1 h of sintering, but materials containing 10, 12 and 16 mol% BaO remain cubic or tetragonal, their transformability being the same as that of materials sintered at lower temperature. The grains growth kinetic during the sintering process is similar to that of the BaZrO3, and the resulting microstructures showed coarser grains than those observed in sintered tetragonal zirconia materials stabilized with other oxides. The crystal structures of cubic or tetragonal BaO stabilized zirconias seem to be isostructural to BaZrO3 as they have similar cell parameters.