Yazar "Öztürk, Kemal" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim
    Öğe
    Improvement of superconducting properties of MgB2 by changing the argon ambient pressure and sintering conditions
    (Journal of Physics: Conference Series, 2009) Savaşkan, Burcu; Öztürk, Kemal; Çelik, Şükrü; Yanmaz, Ekrem
    We have investigated various characteristic properties depending on sintering conditions of MgB2 samples prepared by the standard solid state reaction method. It is inferred from experimental results that the crystallinity of samples were improved when the pressure of the Ar ambient increased. Also, it was found that the sintering temperature above 850 ºC caused extremely high amount of decomposition of the superconductor phase. Finally, it was considered that the sintering process of MgB2 must be carried out under the pressure of Ar ambient higher than 8 bar to impede the volatility of Mg in the structure of MgB2. The Jc values of samples systematically enhanced with the increase of sintering time and in particular, the sample sintered for 180 min. exhibited the highest Jc (0) of 4.9 × 103 A cm?2 at 30 K. The obtained results demonstrate that the sintering conditions of MgB2 have a significant influence on Tc (onset) and Jc, which are directly related to practical applications of MgB2 based superconductor components.
  • Küçük Resim
    Öğe
    Investigation of effect of x in Yb1-xGdxBa2Cu3O7-y superconducting structures on upper critical magnetic field and coherence length.
    (Journal of Physics: Conference Series, 2009) Çelik, Şükrü; Öztürk, Kemal; Yanmaz, Ekrem; info:eu-repo/semantics/openAccess
    The resistivity measurements of the Yb1-xGdxBa2Cu3O7-y superconducting samples prepared by using the solid-state reaction technique for x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 were performed in QD-PPMS system under different magnetic fields up to 5T in zero field cooling regime. The upper magnetic field Hc2(T=0) for each sample was calculated from 50% of the normalized resistivity (Rn) by the extrapolation Hc2(T) to T=0K and the coherence lengths x(T=0) of the samples were calculated from the Hc2(0) values. The examination of the effects of x in the composition on Hc2(0) showed us that the upper critical magnetic field decreased from 186.31T for x=0.0 to 37.99T for x=1.0 with the increasing of content x from x=0.0 to 1.0. Using the content x in the composition, the upper critical magnetic field can be controlled and this can be used in superconducting application especially as a superconducting relays.