Superconductivity and vortex flux pinning in polycrystalline (Eu1.5-xPrxCe0.5)Sr2Cu2NbO10

Magnetization measurements in polycrystalline (Eu1.5-xPrxCe0.5) Sr2Cu2NbO10 were done at 4.2 K at different con-centration of Pr ions x = 0, 0.2 and 0.3. Our results revealed that as the magnetic ion of Pr increases the supercon-ductor state disappeared at x = 0.3. The pinning forces decreases with increasing Pr concentrations. This indicates that the magnetic Pr ion acts to weaken the pinning forces. This is attributed to strong parmagnetism.