JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, cilt.27, sa.3, ss.711-716, 2014 (SCI-Expanded)
The superconducting Bi1.6Pb0.4Sr2Ca2Cu3-x W (x) O10+y (x=0.00, 0.05, 0.10, 0.15) bulk samples were prepared by the solid-state reaction method. The effects of W substitution on the BSCCO system have been investigated by the electrical resistivity (rho-T), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), magnetic hysteresis and critical current density measurements. It has been found that the Bi-(2212) low-T (C) phase is formed for all the substitution levels, together with the Bi-(2223) high-T (C) phase. The results obtained from the XRD data show that the Bi-(2223) phase gradually transforms into the Bi-(2212) phase with increasing W substituting for Cu. In addition, from the magnetization measurements at the temperatures below the zero resistance temperatures of the samples, we have observed that a decreasing in magnitude of |M| with the increasing measurement temperature and W concentration. Therefore, the decreasing of |M| related to superconducting volume seems to imply an existence of flux-pinning centers in our samples.