EFFECT OF DOPING ON THE MAGNETIC-ANOMALIES IN PR1.5CE0.5SR2CU2NBO10

Pure Pr1.5Ce0.5Sr2NbCu2O10 is not superconducting and magnetic suscept ibility data reveal two magnetic anomalies at T(1)=11 and T-N(2)=54 K. Pr1.5Ce0.5Sr2Nb(Cu(1-x)M(x))(2)O-10 where M=Fe,Zn,Cd, Ni and Ga, were observed only for the second peak which is extremely sensitive to the dopant concentration and shifted to higher temperatures. For a given M, T-N(2) increases with the nominal dopant concentration. The largest shift is observed for M=Fe, e.g. for x(Fe)=0.05 T-N(2)=117 K. No spec ific correlation could be found between the temperature shift and the character of the dopant M. For substitutions made outside the CuO2 pla nes no change in T-N(2) occurs.