Yazar "Koparan, Ezgi Taylan" seçeneğine göre listele

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    Öğe
    Enhanced Magnetic Levitation and Guidance Force in MgB2 Bulks by Synthetic Engine Oil Immersion
    (Springer, 2019) Savaskan, Burcu; Koparan, Ezgi Taylan; Guner, Sait Baris; Ozturk, Kemal; Celik, Sukru
    We have used Synthetic engine oil' as a rich easily accessible carbon source and investigated the effect of engine oil on the microstructure, critical current density (J(c)), vertical levitation force (F-z) and guidance force (F-x) properties of MgB2 superconductor. The polycrystalline disk-shaped MgB2 bulk samples have been prepared using two-step solid-state reaction process. After the first heating process, MgB2 bulk samples immersed in the engine oil for different durations (30, 120, 300 and 1440 min). XRD analysis indicated the decreasing of lattice parameters of samples and confirmed C substitution in boron sites. Vertical levitation and guidance force measurements were carried out with both Field-cooling (FC) and zero-field-cooling (ZFC) regimes at different temperatures of 20, 24 and 28 K. It was found that engine oil addition slightly increases the levitation and guidance force properties. The Fz values were obtained as 11.17 and 11.58 N for pure and MgB2 sample immersed for 30 min at 20 K in ZFC regime. In addition, the MgB2 sample immersed for 300 min in engine oil showed the highest Jc value of 5.3x104 A cm(-2) at 15 K and self-field and showed the highest guidance force value of 4.14 N at 20 K. These finding suggest that synthetic engine oil is a cost-effective and promising method to improve the levitation and guidance force performance as well as the critical current density of MgB2 bulk superconductor.
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    Öğe
    Investigation on superconducting and magnetic levitation force behaviour of excess Mg doped-bulk MgB2 superconductors
    (Elsevier Sci Ltd, 2019) Guner, Sait Barb; Savaskan, Burcu; Ozturk, Kemal; Celik, Sukru; Aksoy, Canan; Karaboga, Firat; Koparan, Ezgi Taylan
    A series bulk samples of MgB2 + x wt% of Mg (x = 0, 5, 10, 15, 20 and 30) were fabricated by solid state reaction method. The structural and electromagnetic properties of MgB2 samples were studied using X-ray diffraction (XRD), scanning electronic microscope (SEM), electrical resistivity (R-T), magnetic hysteresis (M-H), magnetic levitation (F-z) force and lateral force (F-x) measurements. The maximum repulsive and attractive force values of 15 wt% of excess magnesium MgB2 sample compared to the other samples imply that the intergranular connection between grains enhanced while pore and microcrack density decreased which brings an increase in the values of the radius of a shielding current loop (r) and the critical current density (J(c)). It was determined that to obtain the enhancement of the micro and macro structure properties, causing to the higher critical current density, and the maximum levitation and lateral force values, the optimum excess magnesium content was 15 wt % into sample. It is thought that an addition of 10-15% excess magnesium can be tried for spark plasma or other methods -as a further research- and the results showed a potential to guide the researchers to study on the material-fabrication and the magnetic bearing system.