The addition of Ni impurities can reveal the correlation between crystal structure changes and magnetic properties and superconductivity. In this study, electron-doped cuprates with an addition of the Eu1.84Ce0.16Cu1−yNiyO4+α−δ (ECCNO) Ni impurity, with y = 0.005, 0.01, 0.02, 0.03, and 0.05 in the over-doped regime, was prepared using the solid-state reaction method. The XRD results showed that ECCNO has a T’ crystal structure, and lattice parameter c increases when parameters a and b decrease, which causes the distance between the charge reservoir and the conducting layer to become greater, thus affecting magnetic properties. From the superconducting quantum interference device’s measurement, it was observed that the magnetic properties of all samples with Ni impurities show a paramagnetic phase, indicating that the effect of Ni impurities could suppress the superconducting phase. It was observed that the Curie constant and the effective magnetic moment tended to decrease for y ≤ 0.02 and began to increase when y > 0.02. This behavior indicated that the effect of the Ni impurity weakened the dynamical Cu spin–spin correlation, which might be related to stripe correlations.
