A structural study of chemical stability of (Y1−x Ca x)(Ba2−x La x )Cu3O7−δ(x= 0.0, 0.2, and 0.4)

Neutron structural studies are made on (Y_1?x Ca _x)(Ba_2?x La _x )Cu₃O_7?δ for compositions corresponding to x=0.0, 0.2, and 0.4 in order to evaluate any correlation between the remarkably high chemical stability of the cosubstituted samples (x=0.2 and 0.4) and the structural parameters. It is suggested that the increased chemical stability is caused by a decrease in the puckering of the Cu-O planes with increase inx, causing them to flatten, which leads to a reduction in the internal stresses existing in the perovskite lattice of this technologically important material.