PEROVSKITE SOLID-SOLUTIONS IN THE BAO-CUO-Y2O3-WO3-SYSTEM

Freeze dried complex carboxylates are highly reactive precursors for c omplex perovskite solid solutions in the system BaO-CuO-Y2O3-WO3. On t hermal decomposition of the amorphous freeze-dried carboxylates the pe rovskite formation begins at about 600 degrees C and is finished in mo st cases at 900...1000 degrees C. Beginning from the composition Ba2YC u2WO8,5, a partial substitution of W by Cu, Y by Ba and cosubstitution of Y by Ba and Cu by W lead to more or less extended fields of solid solutions with an ordered cubic perovskite structure, The partial subs titution of Y by Cu and the cosubstitution of Y and W by Cu, connected with the substitution of Ba by Y, in Ba2Y2/3WO6 also results in the f ormation of perovskite solid solutions. The composition of the complex oxide phases strongly depends on the preparation conditions. This fac t explains the different results described in the literature concernin g the composition of perovskite phases in the system BaO-CuO-Y2O3-WO3.