The effect of partial calcium substitution for strontium on the oxygen stoi
chiometry, T-c, Delta T-c, j(c), and rho of 2212 was studied. The way in wh
ich the superconducting properties of the material vary with annealing temp
erature was found to depend strongly on the Sr/Ca ratio. The possible mecha
nisms of the observed behavior are discussed. The conclusion is drawn that
the strong effect of structural ordering on T-c disguises the correlation b
etween the transition temperature and oxygen stoichiometry.