Perovskite solid solutions in the BaO-CuO-Y2O3-Nb2O5 system

Freeze dried complex carboxylates are highly reactive precursors for complex perovskite solid solutions in the system BaO-CuO-Y2O3-Nb2O5 On thermal decomposition of the amorphous precursors the formation of complex crystalline phases begins at 600°C. In most cases the themiodynamically controlled phase composition is reached after a reaction time of two hours at about 900degreeC. Beginning from the perovskite compound Ba2YNbO6 a partial substitution of Y by Cu or by a combination 2/3 Cu,l/3 Nb leads to extended fields of solid solutions with cubic perovskite structure. Substitution according to Y0,5Ba2(Y1-0,5xCuxNb)O6+x is limited to x<0,4. A compound LBa2Cu2NbO8 (x=2), well characterized for L=La, does not exist for L=Y. The composition of solid solutions depends on the preparation conditions. There are some signs for an inhomogeneous distribution of B-cations in the cubic perovskites.