High-temperature superconducting samples of Y1-xNi x Ba2Cu3O7??_ with 0:0 _ x _ 0:03, were prepared by the conventional solid-state reaction. The AC magnetic susceptibility analysis was performed. By plotting the magnetic susceptibility diagram of the samples as a function of temperature and checking its behavior as a funaction of Ni doping, we observed an incremental behavior in Tc, transition temperature, up to an optimum concentration of Ni, and then the superconducting transition temperature decreases with further concentration of Ni. In order to confirm the results of the magnetic susceptibility, the electrical resistance analysis of the samples was performed. In the normal state resistivity, variations in temperature are linearly, indicating the metal behavior of the samples. Also we observed that by increasing the Ni ion, the superconducting transition temperature of the samples increases to an optimal value of doping. It is in agreement with the results of the magnetic susceptibility. For checking of the flux pining and the quality of interconnections of the grains in samples, in samples the magnetoresistance of samples were measured under magnetic fields up to 1 T. By investigating the broadening behavior in the electrical resistance of the samples, we observed that the bonding between the grains increased up to an optimum value of Ni doping. X-ray diffraction analysis was also performed to investigate structural changes in the samples. Data was analyzed by Rietveld refinement method. All samples have an orthorhombic structure with Pmmm symmetry. The lattice parameter c is increased, the CuO2 planes become more distorted and the intergarin connections improved, up to the optimal value of Ni doping. The SEM analysis of the samples was carried out. The grain size was increased and improved connections, up to the optimal value of Ni doping.
