We have measured the change in the resistive T c of Bi 2 (SrCa) 2ϩn (Cu 1Ϫx M x ) 1ϩn O y whiskers due to substitution of M ϭ Ni ͑magnetic͒ or M ϭ Zn ͑nonmagnetic͒ for Cu. These whisker crystals show resistance drops for both the 2212 and 2223 (nϭ1,2) phases, with transition widths ͑10-90 %͒ of 1 K. We checked the effect of oxygenation at several values of x, and found that T c is maximum for the y obtained by growing and annealing in 1 atm of O 2 . We observed a linear depression of T c for both 2212 and 2223 phases with DϭdT c /dxϷϪ800 K for both Ni and Zn. This is in contrast with YBCO in which D Zn Ϸ3D Ni .

No abstract

No abstract

No abstract

No abstract