Investigation of Ni Substitution for Cu in Bi(Pb)-Sr-Ca-Cu-O Superconductor by AC Magnetic Susceptibility Measurements

st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} In this work we have investigated the effect of doping of magnetic element Ni for copper into the copper site of Bi(Pb)-Sr-Ca-Cu-O superconductor by means of AC magnetic susceptibility measurements. Three samples with composition Bi 1.6 Pb 0.4 Sr 2 Ca 2 Ni x Cu 3-x O y with x=0, x=0.05 and x=0.1 were prepared using sol-gel method and the measurements of χ'(T) and χ''(T) were carried out on these samples in zero and in applied d.c magnetic fields. The χ'(T) data for the samples in zero d.c field show single drops indicating that the samples had one superconducting phases and the superconducting transition temperatures of the samples were determined to be 108.7 K, 98.9 K and 56.7 K respectively. Obviously superconducting transition temperatures of the samples decrease with increasing Ni concentration. The χ' (T) data for the samples in d.c magnetic fields show broad superconducting transitions indicating that the magnetic fields quenched superconductivity of the samples. The χ''(T) data in d.c magnetic fields show broad intergrain peaks associated with energy dissipation inside the samples. In low d.c magnetic fields χ' (T) data for the x=0 and x=0.05 samples show two drops associated with inter and intragrain regions of the samples. In high magnetic fields χ' (T) data show single transitions indicating that the magnetic fields simultaneously penetrated into the superconducting grains and the weak links. The χ' (T) data for the x=0.1 sample shows single drops in low and in high d.c. magnetic fields. The high d.c magnetic fields pushed the superconducting transition temperatures of the samples to lower temperatures and the intergrain peaks in χ''(T) shifted to lower temperatures with increasing applied d.c magnetic fields. doi:10.4038/sljp.v3i0.185 Sri Lankan Journal of Physics, Vol.3 (2002) 53-61