The influence of substitution of Ba2+ with Sr2+ On superconducting and
magnetic properties of ceramic RBa(2-x)Sr(x)Cu(3)O(7-delta) (R = Gd,
Dy; x = 0.5, 1.0) samples with different oxygen content has been inves
tigated. In contrast to YBCO, RBa(2-x)Sr(x)Cu(3)O(7-delta) becomes sup
erconducting in a narrow range of delta between 0 and 0.35. Magnetic p
hase diagrams were constructed for these compounds.