THE INFLUENCE OF Pb, Ni AND V DOPING ON THE CHARACTERISTICS OF HIGH-T_cBi-Si-Ca-Cu-O SUPERCONDUCTORS

Abstract

We report on the studies of ac susceptibility, ultrasonic attenuation, superconductivity and some calorimetric measurements on Pb -doped for Bi -site as well as Ni and V substitution for Cu in Bi-Sr-Ca-Cu-O superconductors. It was confirmed that the Bi(Pb)-based glass ceramics (i.e. crystallized glasses) exhibit superconductivity with T c above 105 K higher than Bi(Ni) with Tc 68 K and Bi(V) -based glasses with T c 40K. X-ray diffraction analysis revealed that the structure of these materials is Bi -2223 type with a=4.067 Å and C=30.768 Å. It was found from the temperature dependence of ac complex susceptibility that the coupling nature at grain boundaries of superconducting crystals in the samples obtained was weak, and was improved by increasing the annealing time. Data are discussed for varying T c of different substituents. Our results on the ultrasonic attenuation revealed a series of relaxation peaks with low activation enthalpies which indicate that electronic defects may be the cause for the relaxation processes.

Vortex penetration in shunted type II superconducting strips

“…Among them, the powder-in-tube (PIT) method is the most promising technique to produce tapes for large scale applications. Many papers have been published on the study of the Bi-2223/Ag tape [1][2][3][4][5][6]. To optimize the devices using the tape, the magnetic field and current distributions in the tape must be well understood.…”