SUPPRESSION OF SUPERCONDUCTIVITY IN THE (ER1-X-YPRXCAY)BA2CU3O7-DELTASS-THAN-OR-EQUAL-TO(X,Y)LESS-THAN-OR-EQUAL-TO-0.3) SYSTEM

Pr- and Ca-substituted (Er1-x-yPrxCay)Ba2Cu3O7-delta superconductors h ave been prepared under identical conditions and characterized accordi ng to resistivity and AC susceptibility measurements. The observed red uction of T(c) with x in (Er1-xPrx)Ba2Cu3O6.90 for 0 less-than-or-equa l-to x less-than-or-equal-to 0.3 can be described by an empirical rela tion which incorporates the filling (or localization) of mobile holes in the CuO2 planes and magnetic pair breaking by local moments. In a s imilar way, the observed lowering of T(c) with increasing y in (Er1-yC ay)Ba2Cu3O7-delta provides convincing evidence that superconducting el ectron pair breaking and hole doping are responsible for the suppressi on of superconductivity by Ca.