O. Cakiroglu

Electrical Properties of High Temperature Insulation Coatings under various Pressures at 298 K and 77 K

The high temperature insulation coatings were prepared using solution of Mg and Zr based precursors. Then the MgO‐ZrO2 coating was applied on long‐length Stainless‐Steel tapes using a non‐vacuum reel‐to‐reel sol‐gel dip coating technique. The thicknesses of coatings 7, 12 and 15 μm for 4, 8 and 12 dip, respectively. Three different types of stycast, 2850 FT/24 LV Black and Blue, and White Buechler Epoxide Resin were studied. Stycast thicknesses were varied from 32–18 μm, when pressure was applied from 0 to 0.54 GPa. Electrical properties of the coated tapes were investigated under various pressures at room temperature (298K) and in liquid nitrogen (77K).

Nonvacuum Deposition of Silver Doped YBCO Coated Conductor on %100 Lattice Match Buffered Ni Tapes

Silver doped YBa2Cu3O7−δ (YBCO) coated conductors were fabricated on Gd1.624Ho0.376O3 (100 % lattice match with YBCO) textured buffer layers on Ni tape by reel‐to‐reel sol‐gel dip coating system. Sample were prepared with different wt(1–5) % Ag doped ratio. The surface morphologies and microstructure of all sample were characterized by ESEM, EDS and XRD. Pole figure texture analyses have been done to characterize texture of buffer layer and YBCO superconducting film . The critical current Ic measurement was performed using four wire method with the 1 μV/cm criterion. The critical current density, Jc was measured to be 2.2 × 104 A/cm2 at 77 K self field for 1 wt % Ag doped YBCO sample.

Mean Field Approach to the Correlation Effects on the Density of Electronic States and Conductivity of Disordered Metals

Effects of correlation in weakly disordered systems on the density of electronic states (DOS) and the conductivity are examined in the framework of the mean field approach. As a result of the approximation, the electronic energy spectrum is changed from a free electron energy spectrum to a Hartree exchange term added energy spectrum form. Coulomb interaction is shown to give a correction to the DOS, which reduces the electronic states. Calculations of the conductivity show that, although Coulomb interaction evaluated by the mean field theory decreases the Drude conductivity, it acts as a dephasing factor for the quantum localization correction to the conductivity.

Fluctuations of the Order Parameter's Phase in Layered Superconductors

The influence of the quantum fluctuations of the order parameters phase on the critical temperature Tc is studied for a Josephson coupled layered superconductor. Two characteristic critical temperatures exist for a system, namely the superconducting critical temperature T(2)c for a single layer estimated by the mean-field theory and the transition temperature for the outset or the superconducting phase coherence T*c. The true critical temperature Tc is shown to vary inside the intervals T*c ≤ Tc ≤ T(2)c. For a strong quantum phase fluctuation limit, the superconducting layers become decoupled.