Yazar "Yilmazlar, Mustafa" seçeneğine göre listele

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  • Küçük Resim
    Öğe
    Investigation of Sm → Ca substitution in Bi(Pb)SrCaCuO high temperature superconductor by low field AC magnetic susceptibility
    (Springer, 2007) Terzioglu, Cabir; Yegen, Dincer; Yilmazlar, Mustafa; Görür, Osman; Akdogan, Mustafa; Varilci, Ahmet
    We have investigated the effect of Sm substitution in Bi(Pb)SrCaCuO system by performing AC susceptibility (chi = chi' + i chi ''), XRD (X Ray Diffraction) and SEM (Scanning Electron Microscopy) measurements. The Sm -> Ca substitution (Bi(1.)6Pb(0.4)Sr(2)Ca(2-x)Sm(x)Cu(3)O(y)) was carried out by conventional solid-state reaction method. The susceptibility measurements were carried out at different values of the AC field amplitudes. The imaginary part of susceptibility is used to estimate the intergranular critical current density by means of the Bean's model. The intergranular critical current density (J(c)) of pure sample is found to be about 68 A/cm(2) at 95 K. The intergranular J(c) is seen to decrease with increasing Sm substitution. XRD pattern and SEM micrographs are given to provide information about Bi-2223 phase and grain size respectively.
  • Küçük Resim
    Öğe
    Structural and physical properties of Sm-doped Bi1.6Pb0.4Sr2Ca2-xSmxCu3Oy superconductors
    (Elsevier Science Bv, 2005) Terzioglu, Cabir; Yilmazlar, Mustafa; Öztürk, Özgür; Yanmaz, Ekrem
    The superconducting Bi1.6Pb0.4Sr2Ca2-xSMxCu3Oy (X = 0.0, 0.0005, 0.001, 0.005, 0.01, 0.1, 0.5, 1.0, and 1.5) system was investigated for different concentrations of Sm. The structural analysis was carried out by XRD. XRD results show that the samples with substitution of various amounts of Sm for Ca transform from the major high-T-c phase (Bi-2223) to the low-T-c phase (Bi-2212). The lattice parameter data extracted from XRD showed that with increasing Sm concentration (x), the lattice parameter a increases slightly while the lattice parameter c decreases significantly. DC resistivity measurements were carried out by the standard four-probe technique in the temperature range between 25 K and 130 K. With increasing Sm substitution up to x = 0.1, the values of T-e(offset) vary between 107 K and 70 K. The samples with x > 0.1 did not show any superconducting transition down to 25 K. The critical current density measurements were performed in liquid nitrogen. Critical current density decreases with increasing Sm substitution, and it was measured to be 43 A/cm(2) for the sample with x = 0.0 at zero field. Microstructure examinations were carried out by SEM. All the reported data were discussed, and compared with earlier results on Sm and other substituted Bi-Sr-Ca-Cu-O system. (c) 2005 Elsevier B.V. All rights reserved.