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    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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    Lateral Force Measurements for (Gd123)1-x :(Gd211) x Superconductors at Different Temperatures
    (Springer, 2017) Guner, Sait Baris; Celik, Sukru; Cansiz, Ahmet; Ozturk, Kemal
    The lateral levitation force between melt-textured (Gd123)(1-x) :(Gd211) (x) bulk superconductors for x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5 and a permanent magnet is measured at 30, 40, 50, 60, and 77 K under zero-field-cooling and field-cooling conditions. The variations on the observed levitation force are correlated to the varied content of Gd211 in these melt-textured samples.
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    Magnetic levitation force and trapped field properties of multiseeded YBCO with triangular arrangement of seeds
    (Wiley, 2022) Abdioglu, Murat; Guner, Sait Baris; Ozturk, Kemal; Yang, Chiaming; Chen, Ingann; Celik, Sukru
    Although there are studies in literature using different number of seeds with different arrangements, especially line and rectangular, it is seen that there is no detailed study handling the levitation force together with trapped field properties of triangular arrangement of seed in YBCO. Therefore, to further investigate the magnetic properties of seeded YBCO superconductors, we have fabricated cylindrical YBCO (YBa2Cu3O7) superconductors with triangular arrangement of the seeds with different seed distances. Maximum levitation force values were obtained as 39.4 N and 57.1 N, while the maximum guidance force values were obtained as -4.6 N, and -8.7 N, respectively, with single-seeded and triangular-seeded samples with seed distance of 14 mm. It was determined that the trapped field, levitation force, and guidance force firstly decreased from the single-seeded sample to the triangular-seeded sample with small seed distance and then increased with increasing seed distance. Increased field trapping and levitation force performances in the triangular-seeded samples with suitable seed distance indicate that the triangular arrangement of seeds is an eligible method to produce larger dimension YBCO samples with bigger shielding current radius and bigger averaged trapped field values.
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    Superconducting and levitation force characterisation of pyrene added MgB2 bulk superconductors
    (Elsevier Sci Ltd, 2020) Erdem, Ozge; Guner, Sait Baris; Celik, Sukru; Kucukomeroglu, Tayfur
    This research presents the influence of pyrene (C16H10) addition (0, 2, 4, 6, 8, 10 wt%) on the superconducting properties of bulk MgB2. For C16H10 added MgB2 samples, a shrinkage in a-lattice parameters was determined, whereas c-lattice parameters remained practically unchanged. The (110) peak observed at 2 theta approximate to 59.9 degrees slightly shifted to higher angles, the lattice strain increased and the crystallite size reduced after C16H10 addition. By virtue of induced stronger pinning force, the in-field critical current density (J(c)) increased after C16H10 addition. The J(c) value at 20 K and 4 T was obtained about two times higher (8.54 x 10(3) A/cm(2)) for 4 wt% C16H10 added MgB2 sample than that of the pure one. In addition, the variation of levitation force characteristic of MgB2 with increasing C16H10 content was determined at 20, 25 and 30 K. The best vertical levitation force performance in zero-field-cooled regime was obtained as 7.09 N/g at 20 K for 4 wt% C16H10 added MgB2 sample with 13 mm in diameter.
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    The comparison of levitation and lateral force of bulk and cut-pasted bulk GdBCO samples at different temperatures
    (Elsevier Science Sa, 2020) Guner, Sait Baris; Abdioglu, Murat; Ozturk, Kemal; Celik, Sukru
    In this work, in the first time, we have investigated the levitation and lateral force properties of bulk and cut-pasted bulk GdBCO samples at different temperatures and different cooling heights (CH) to determine the effect of cut-pasted process on the magnetic levitation force behaviour. The measurements of superconducting characteristics indicated that the attractive and repulsive force values of cut-pasted GdBCO sample are slightly lesser than those of GdBCO bulk sample. The maximum repulsive and attractive force values obtained as 15.45 N and -4.56 N for GdBCO bulk and as 14.78 N and -3.92 N for cut-pasted GdBCO samples at 37 K. Although there are many fabrication methods as melt-textured growth (MTG), top seeded infiltration growth (TSIG) and TSMG to produce large HTS samples, the desired large sample size and the sample shape compatible with the superconducting magnetic bearing systems are not still sufficient for the technological applications. In this study, the performed cut-pasted process and obtained magnetic levitation force data can be using for the increment sample size and the desired sample shape in the needed different geometry and size for superconducting magnetic bearing systems. (C) 2020 Elsevier B.V. All rights reserved.
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    The investigation of magnetic levitation performances of single grain YBCO at different temperatures
    (Elsevier Science Sa, 2017) Guner, Sait Baris; Celik, Sukru; Tomakin, Murat
    The temperature dependence of the magnetic levitation force has been investigated for single-grain YBCO bulk sample, 20 mm in diameter with a thickness of 8 mm, fabricated by top-seeded melt growth (TSMG) method using Nd123 seeded. The superconducting properties of the single grain YBCO bulk are studied by VSM (Vibrating Sample Magnetometer), the microstructures and the phase constituents of those that are seen by SEM (Scanning Electron Microscope) and XRD (X-ray Diffraction). The measurements of superconducting properties indicated that magnetic levitation forces of the sample were found 11.23, 10.81, 10.34, 9.23 and 7.02 N at the temperatures of 37, 47, 57, 67 and 77, respectively, and the values of the onset critical temperature (Tc) and the zero-field critical current density (Jc) are 89.3 K and 5.6 x 10(4) A/cm(2) at 77 K, respectively. This research is intended to help for the large scale superconductor levitation performances at different temperatures. (C) 2017 Elsevier B. V. All rights reserved.