In this study pseudoquaternary rare-earth nickel borocarbide superconductors RxR1-xNi2B2C have been investigated predominantly in the diluted limit x << 1 or (1 x) << 1. In all of these materials structural disorder results in a reduction of the supe
rconducting transition temperature Tc . Depending on the selection of the rare earth elements R and R this disorder induced deterioration of superconductivity is combined with magnetic pair breaking of Abrikosov-Gorkov type or pair breaking of non-magnetic impurities in antiferromagnetic superconductors (Morozov-type of pair breaking).
