Growth and Characterization of High-Quality Single Crystals of Ni- and Zn-Doped Bi₂Sr₂Ca(Cu_2?xM_x)O_8+δ (M = Ni or Zn) High-Temperature Superconductors

High-quality large single crystals of Ni- and Zn-doped Bi₂Sr₂Ca(Cu_2?xM_x)O_8+δ (M = Ni or Zn) have been successfully grown by the traveling solvent floating zone technique. The single crystals are characterized by compositional and structural analyses and their physical properties are investigated by magnetic susceptibility and resistivity measurements. A record high critical temperature with a T_c=97.5 K has been achieved in the annealed pristine Bi2212 single crystal. Substitution of Cu by Ni or Zn reduces the superconducting transition temperature when compared with pristine Bi₂Sr₂CaCu₂O_8+δ (Bi2212) grown under similar conditions. The successful growth of such pristine Ni- and Zn-doped Bi2212 single crystals will facilitate studies of the relationship between the magnetism and superconductivity in high-temperature cuprate superconductors.