Bi2Sr3-yCayCu2Ox can be obtained at 1 less than or equal to y less tha
n or equal to 1.75 and 7.9 less than or equal to x less than or equal
to 8.3. The lattice parameter c and the transition temperature T-c inc
rease at decreased y and increased x. The y = 1 compound is stable abo
ve similar to 700 degrees C at 8.04 less than or equal to x less than
or similar to 8.3 and decomposes at decreased temperatures or decrease
d oxygen content x. Metastable phases with x = 7.9 were obtained by re
action with H-2 at 250-310 degrees C.