Yazarlar
Yayınlar
- MakaleYalnız künye2024Scopus SJRQ3Comparison of Superconducting Properties of Bulk MgB2 Samples with Pyrene Additive Produced by B Powder and C encapsulated B Powder
Erdem, Özge
In this paper, the advantages and disadvantages of using B powder and C encapsulated B powder as a precursor during the production process of MgB2 with the addition of pyrene (C16H10) were investigated. Two MgB2 bulk samples with the addition of 10 wt % C16H10 of 1 g MgB2 were produced by the in-situ method using B powder and C encapsulated B powder. The C encapsulated B powder as a precursor was prepared by adding 10% C16H10 as a C source. From XRD and SEM analysis, a greater increase in MgO phase and a greater decrease in a-lattice parameter were observed for the sample produced with B, compared to the sample produced with C encapsulated B. The curves of critical current density (Jc) at 5 K showed a similar character for both samples. The Jc values at 5 K in self field were respectively obtained as 1.52 × 105 A/cm2 and 1.90 × 105 A/cm2 for the samples produced by B and C encapsulated B. The decrement ratio of in-field Jc at 20 K was less affected by increasing magnetic field for the sample produced using C encapsulated B due to the relatively higher increase in the irreversibility field (Hirr) and the upper critical magnetic field (Hc2) values. The Jc values at 20 K and 3 T were respectively determined as 1.49 × 104 A/cm2 and 1.93 × 104 A/cm2 for the samples produced with B and C encapsulated B.
AtıfScopus2WoS2OpenAlex2
İncele - MakaleAçık Erişim2024Scopus SJRQ3Investigation of Hot Press and Cold Press Effects on Structural, Electrical and Magnetic Properties of Pyrene Added Bulk MgB2
Erdem, O.
In this paper, the effects of hot pressing and cold pressing on the superconducting properties of pyrene (C16H10) added bulk MgB2 were compared. For this aim, the polycrystalline disk-shaped MgB2 samples with addition of 4 wt % C16H10 powder were fabricated by a pellet/closed tube method at 850 °C, after hot pressing at 200 °C and cold pressing. The XRD and SEM results showed that although a-lattice parameters reduce for both C16H10 added samples, the average crystallite size increases after cold pressing because of the accumulation and inhomogeneous distribution of C in the MgB2 structure while it reduces for the C16H10 added hot pressed sample. The resistivity measurements showed that the increment of electron scattering is higher for the C16H10 added cold pressed sample than that of the C16H10 added hot pressed one which shows relatively better grain connectivity, and the Tc values of the samples are not appreciably affected by the pressing conditions. From the magnetisation measurements the in-field Jc values at 10 K and 5.5 T were obtained as 8.41 × 103 A/cm2, 1.62 × 104 A/cm2, 6.90 × 103 A/cm2 and the Hirr values while Jc = 100 A/cm2 at 20 K were obtained as 5.99 T, 6.55 T and 6.19 T for the pure sample and the C16H10 added hot and cold pressed samples, respectively. The higher Jc and Hirr values obtained for the C16H10 added hot pressed sample is because of the homogenous C substitution into MgB2 grains, as compatible with its lower Δρ value, and thus increased flux pinning ability.
- MakaleAçık Erişim2021Scopus SJRQ2Magnetic levitation force performance of benzil added bulk MgTi0,06B2 superconductors
Abdioglu, Murat
MgB2 superconductors can be proposed as a good candidate for Maglev systems due to their superior structural and superconducting properties. Besides, magnetic levitation and guidance force properties of these superconductors should be increased for commercial applications of Maglev systems. Therefore, the critical current density and magnetic levitation and guidance force properties of MgTi0.06B2 superconducting samples were investigated in this study, at measurement temperatures of 20 K and 25 K, depending on benzil (C14H10O2) addition in different adding amounts of 0, 1.5, 3, 4.5, 6 and 9 wt%. In addition to benzil, nanometer-sized silver particles were added to the samples in a constant ratio of 2 wt% to enhance the structural properties. The maximum critical current density values increased from 67 kA/cm2 for pure sample to 92 kA/cm2 with benzil adding amount of 3 wt% at T = 20 K, indicating an increment of 37%. In addition, the levitation force in ZFC (zero field cooling) regime and the guidance force in FC (field cooling) regime at 20 K increased at an amount of 46% and 57%, respectively, with 3% benzil addition. It can be said that the suitable amount of benzil addition as a carbon source produces additional pinning centres inside the MgTi0.06B2 and thus structural properties, critical current density and therefore, magnetic levitation properties of the samples are increased.
AtıfScopus3WoS3OpenAlex3İncele - MakaleAçık Erişim2020Scopus SJRQ2Superconducting and levitation force characterisation of pyrene added MgB2 bulk superconductors
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 (1 1 0) peak observed at 2θ ≈ 59.9◦ 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 (Jc) increased after C16H10 addition. The Jc value at 20 K and 4 T was obtained about two times higher (8.54 × 103 A/cm2) 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.
AtıfScopus8WoS6OpenAlex8İncele - MakaleYalnız künye2019Scopus SJRQ2Comparative study of hot and cold press and their effect on superconducting properties of coronene added bulk MgB2
Erdem, O.
In this study, the superconducting properties of 4 wt% coronene (C24H12) added polycrystalline bulk MgB2 samples prepared by hot pressing and cold pressing, were reported in detail. The results were compared to determine one of which pressing methods is more useful to substitute of carbon released from C24H12 into MgB2 structure and to increase the superconducting properties of MgB2. The lattice strain, crystallite size, residual resistivity, superconducting transition temperature (Tc), critical current density (Jc), flux pinning force density (Fp) and vertical/lateral levitation force (Fz, Fx) were analysed for the hot and cold pressed samples. The a-lattice parameter and Tc value reduced sharply for 4 wt% C24H12 added cold pressed sample, resulting in a notable decrease of increment ratio of Jc and Fp values, while the depressing of Tc is lower for 4 wt% C24H12 added hot pressed sample. The cold pressing strongly increased the lattice strain, confirming more C substitution, while the hot pressing ensured smaller crystallite size. The Jc and Fp values were respectively found as 4.6 × 103 A/cm2, 1.3 × 104 A/cm2, 5.8 × 103 A/cm2 and 1.8 × 108 N/m3, 5.1 × 108 N/m3, 2.3 × 108 N/m3 for the pure sample and, 4 wt% C24H12 added hot and cold pressed samples at 20 K, 4 T. The maximum repulsive and attractive levitation force values at 20 K in ZFC and FC regimes were obtained for the 4 wt% C24H12 added hot pressed sample. Finally, the hot pressing provides an effective way to substitute C into MgB2 lattice without a remarkable decrease of Tc value, ensuring more homogenous and compacted structure, more electron–phonon interaction and strong flux pinning force.
AtıfScopus6WoS6OpenAlex6İncele - MakaleAçık Erişim2017Scopus SJRQ3Enhanced Pinning Properties of Laser-Irradiated Bulk MgB2 Superconductors
Erdem, O.; Yanmaz, E.
In order to investigate the effect of laser irradiation on the superconducting properties of MgB2, a pellet-shaped sample was produced and cut into two pieces. The dot-shaped molten patterns, with the distance of 100 µm between them, were formed on the surface of one of the pieces by using an Nd:YVO4 laser. The grains of the irradiated sample were significantly grown due to the laser-induced sintering. The modified surface appeared to have dense and compacted grains as a result of increasing interconnectivity among the superconducting grains. The critical current densities at 5 K in a field of 3 T were found to be 5.38 × 104 and 8.96 × 104 A cm−2 for the reference and the irradiated samples, respectively. The increment of critical current density for the irradiated sample is presumably connected with the changing of pinning mechanism after the laser irradiation. For the irradiated sample which showed a higher value of critical current density at 5 K under high fields, Δκ pinning was obtained as a dominant pinning mechanism, while the normal point pinning was dominant for the reference one. These results point out that the superconducting properties of bulk MgB2 can be changed and improved via laser irradiation in a short time.
AtıfScopus12WoS10OpenAlex11İncele - MakaleAçık Erişim2017Scopus SJRQ1Improvement in levitation force performance of bulk MgB2 superconductors through coronene powder adding
Erdem, O.; Abdioglu, M.; Guner, S.B.; Celik, S.; Kucukomeroglu, T.
The effect of coronene (C24H12) addition on the levitation force properties of MgB2 superconductor has been investigated for the first time in this study. The polycrystalline disk-shaped MgB2 + y wt % C24H12 samples (y = 0, 2, 4, 6, 8, 10), were synthesized by a pellet/closed tube method at 850 °C under Ar atmosphere, after hot pressing at 200 °C. XRD analysis indicates a decrease in lattice parameters of coronene added samples and confirms substitution of carbon in boron sites. An increase in lattice strain and a decrease in grain size are observed due to the carbon substitution effect. Vertical and lateral levitation force measurements under zero-field-cooled and field-cooled regimes were carried out at different temperatures of 20, 25 and 30 K. It was found that the coronene addition significantly increases the high-field critical current density of MgB2. The Jc values were obtained as 4.6 × 103 Acm−2 and 1.3 × 104 Acm−2 for pure and 4 wt % coronene added samples at 20 K and 4 T. In addition, the levitation force measurements show that 4 wt % coronene adding is very effective in increasing both the vertical and lateral levitation force performances at 20 K. The maximum levitation force for 4 wt % coronene added sample corresponds to 7.58 N/g whereas the reference sample shows 6.73 N/g at 20 K in ZFC regime. The results point out that the hydrocarbon of C24H12 is an effective carbon-containing additive for MgB2 and can be useful for optimizing the levitation performance of MgB2 superconductors for potential applications.
AtıfScopus25WoS21OpenAlex27İncele - MakaleYalnız künye2015Scopus SJRQ2Effect of Er doping on the superconducting properties of porous MgB2
Erdem, O.; Yanmaz, E.
MgB2 bulk sample with porous structure was produced by using the in-situ solid-state reaction method under argon (Ar) atmosphere of 10 bar. Elemental Er in powder form was doped into MgB2 with different compositions (Mg1-xErx)B2, where x = 0.00, 0.03 and 0.05, in order to investigate the effect of rare-earth (RE) element Er on the structural and electromagnetic properties of porous MgB2. The Er-doped samples result in small grain size structure compared to the undoped one. The lattice constants a and c of the doped samples, determined from X-ray diffraction (XRD) analysis, increase with the increasing Er content, and consequently the superconducting transition temperature (Tonsetc) of MgB2, determined from resistivity measurements, is slightly suppressed. Also, the upper critical field (Bc2), the irreversibility field (Birr) and the critical current density (Jc) values are significantly enhanced in the doped samples. For the best sample (x = 0.03), at 15 K under a magnetic field of 4 T, the Jc value reaches 2.4×104 A cm-2, which is higher than that of the porous sample by an order of 103, and the Birr value at 20 K reaches 9.7 T. These results imply that the RE element Er fills the pores, enhances the density and the grain connectivity. Hence, the superconducting properties of the porous MgB2 sample improve by Er doping.
AtıfScopus13WoS11OpenAlex12İncele