WHY DOES Y2BA4CU7O14- PREDICTIONS FROM OXYGEN ORDERING(X NOT EXHIBIT A PLATEAU IN ITS TC(X) DEPENDENCE )

On the basis of the (T, x) phase diagrams of oxygen ordering, the amou nts of transferred holes n(h) as a function of x are calculated for pu re as well as for doped samples of YBa2Cu3O6+x and Y2Ba4Cu7O14+x. Thes e calculations allow us to anticipate the behavior of the superconduct ing temperature T(c)(x). In pure Y2Ba4Cu7O14+x a small kink is observe d in n(h)(x) at x = 0.5, instead of the plateau characteristic to YBa2 Cu3O6+x. Substitution of Cu in the basal plane by Al or removing Cu wi thout substitution also leads to a smearing of the plateau.