Study on the properties of Sn-added YBCO prepared by the powder melting process

Magnetization and magnetic relaxations have been measured for the YBa ₂Cu_2.985Sn_0.015O_y and YBa ₂Cu₃O_y superconductors, which were prepared by the powder melting process method. It is found that the Sn-added sample exhibits much higher J_c value and lower flux creep rate than pure YBCO. The results indicate that the melting temperature can be reduced and the pinning potential can be enhanced by substituting Sn for Cu. The J_c value estimated by Bean's model drops with the magnetic field according to a power law. The dependence of J_c on the reduced temperature and the flux pinning force density behavior is discussed. The dependence on temperature of the maximum demagnetization field H_p and the remanent magnetization M_rem is studied. Finally, we also investigate the microstructure characteristic.