Yazarlar
- Başoğlu, M.(3)
- Başoğlu, Mehmet(2)
- Düzgün, I.(2)
- Düzgün, İbrahim(2)
- Çelebi, Selahattin(2)
- Öztürk, A.(2)
- Öztürk, Ali(2)
- Aydiner, Alev(1)
- Açikel, S.(1)
- Başoǧlu, Mehmet(1)
- Cumhur, I.(1)
- Doğan, Mustafa(1)
- Duman, Şeyda(1)
- Duzgun, I.(1)
- Düzgün, İ.(1)
- Kutuk, S.(1)
- Ozturk, A.(1)
- Uysal, E.(1)
- Çakir, Bakiye(1)
- Çelebi, S.(1)
Yayınlar
- MakaleYalnız künye2025Impact of erbium doping on critical current density and constituent phase in BSCCO superconductors
Açikel, S.; Cumhur, I.; Öztürk, A.; Başoğlu, M.; Düzgün, I.
This work systematically examines the influence of partial substitution of calcium (Ca) by erbium (Er) on the structural integrity and superconducting performance of Bi2Sr2Ca2Cu3O10+δ (BSCCO) high-temperature superconductors. Samples were synthesized through the conventional solid-state reaction method and characterized via X-ray diffraction, scanning electron microscopy, resistivity, and magnetization measurements. Despite the close effective ionic radii of Er and Ca, experimental results revealed that increasing Er content led to a deterioration of the superconducting phase and the emergence of semicon ducting characteristics. Quantitative analyses demonstrated a notable reduction in critical current density (Jc), with undoped BSCCO samples exhibiting approximately 14% higher Jc values under equivalent conditions. These findings suggest that while ionic size considerations may permit Er substitution from a stoichiometric perspective, the structural and superconducting phase stability of the BSCCO matrix is adversely affected by Er incorporation.
- MakaleYalnız künye2023The effect of the Y2O3 buffer layer on the microstructural and physical properties of melt-processed Y358 superconductor
Başoğlu, Mehmet; Çakir, Bakiye; Duman, Şeyda; Aydiner, Alev
The Y3Ba5Cu8O18 (Y358) superconductors were produced using the Melt-Powder-Melt-Growth (MPMG) method. In the crystal growth process, Y2O3 powder was used as a substrate in both powder and tablet form. The first sample was produced without using any buffer layer, the second sample was produced with a powdered Y2O3 buffer layer, and the third sample was produced with a tablet-form Y2O3 buffer layer. The effect of the Y2O3 substrate on the structural and physical properties of the Y358 superconductor samples was investigated. Superconducting phases were observed in all samples of Y358 through XRD measurements, confirming their presence. Samples fabricated using the powder and tablet forms of the Y2O3 substrate had a better microstructure than the sample fabricated without a Y2O3 substrate. The highest critical current density (J c) value was obtained at 77 K for the Y358 sample produced with a Y2O3 powder substrate, and the J c value was calculated as 1.2 × 104 A cm–2 according to the Bean model.
- MakaleYalnız künye2021Specification of Some Superconductivity Parameters by Adding Lutetium to the YBCO (358) Ceramic Superconductor
Başoğlu, M.; Düzgün, I.; Öztürk, A.
Superconducting specimens of Y3-xLuxBa5Cu8O18+δ (where x = 0, 0.2, 0.4, 0.5) ceramic were fabricated via the solid-state route (SSR). The structural and superconducting features of the specimens were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Measurements and calculations were carried out for electrical resistance (R-T) and DC magnetization (M-H). The onset critical transition temperature (Tconset) of the specimens dropped to lower temperatures with the addition of lutetium (Lu). The estimated critical current density (Jc) values of the specimens, depending on the magnetic field, were extracted from the DC magnetization data. The changes in average grain size and bulk critical current density were examined. Improvement was observed in the bulk critical current density with increasing levels of Lu/Y substitution.
- MakaleYalnız künye2020Comparative Investigation on Magnetic Behavior of Partial Rare Earth Element (Re: Lu, Yb, and Dy) Substituted Y0.5Re0.5BCO (123) Superconductors
Öztürk, Ali; Düzgün, İbrahim; Başoğlu, Mehmet; Çelebi, Selahattin
Partial Re (rare earth elements: Lu, Yb and Dy) substituted YBaCuO (123) superconductors synthesized by solid-state reaction (SSR) procedure have been investigated via x-ray diffraction, scanning electron microscopy, a.c. magnetic susceptibility, and d.c. magnetization, and calculations. The measurements of a.c. magnetic susceptibility have been carried out at constant a.c. field amplitude and constant frequency for the samples studied. The temperature dependence of intergranular critical current density (Jcm) has been estimated from the a.c. magnetic susceptibility data. The d.c. magnetization measurements were performed at the temperatures of 5 K, 20 K, and 77 K separately. The variation of critical current density (Jc) with magnetic field (μ0H) has been evaluated from the d.c. magnetization data by using upper and lower branch of the major hysteresis curve. Lu substituted Y0.5Lu0.5BCO (123) sample shows higher critical current density than Yb and Dy substituted samples at low-temperature (lower than 77 K) regions.
- MakaleAçık Erişim2017The effect of sintering in different atmospheres on superconductivity parameters of YBCO
Başoǧlu, Mehmet
YBa2Cu3O7 (Y123) is a superconductor material discovered in 1987 and its transition temperature is above the liquid nitrogen temperature. It is known that superconductor samples produced by the solid-state reaction route are very often sintered in air atmosphere. However, in the presented work, Y123 was prepared by the same technique using a sintering ambient composed of a mixture of oxygen and argon gases for the first time. Critical current densities of the samples were calculated using results of magnetization measurements. It was obtained from magnetization analysis that all the samples exhibited superconductor character. It was also observed that the sample sintered in the 50% oxygen and 50% argon atmosphere showed the highest critical current density.
- MakaleYalnız künye2016Improvement of Current Density of Different Atmosphere-Sintered Y358 Superconductors
Başoğlu, M.; Düzgün, İ.
Y3Ba5Cu8O18 (Y358) which is the last family member of YBCO superconducting material was produced by a solid-state reaction technique. During the production process, superconducting samples were sintered in different atmosphere conditions. XRD measurements of the samples were performed. As a result of the measurements, it was seen that the superconducting phase peaks were formed. Hysteresis loops were calculated and analyzed in the framework of a critical state model including the Meissner current. Meissner currents (IM) were calculated as 0.0062, 0.0037, and 0.0119 for S100, S50, and S0, respectively. It was observed that S50 has the highest critical current density among the other calculated values.
- MakaleYalnız künye2016The Effect of Dy Doping on the Magnetic Behavior of YBCO Superconductors
Öztürk, Ali; Doğan, Mustafa; Düzgün, İbrahim; Çelebi, Selahattin
The effect of dysprosium (Dy) doping on yttrium barium copper oxide (YBCO) prepared by conventional solid-state reaction method has been investigated by means of XRD, AC susceptibility, and DC magnetization measurements. AC susceptibility measurements for sintered YBCO pellets have been performed as a function of temperatures at constant frequency and AC field amplitude in the absence of a DC bias field. DC magnetization measurements were done at 5, 20, and 77 K upon zero field cooling (ZFC) process. The magnetization measurements showed a paramagnetic behavior existing at high magnetic fields. The magnetic field dependence of critical current density of the samples has been estimated from DC magnetization data. The partial Dy substitution for Y on YBCO superconductors improves the bulk critical current density at high magnetic fields and at high-temperature regions (higher than 20 K).
- MakaleYalnız künye2015Magnetic Relaxation in a Y 0.5Lu0.5Ba2Cu3O y Superconductor at Various Magnetization Levels
Çelebi, S.; Ozturk, A.; Uysal, E.; Kutuk, S.; Duzgun, I.
The evolution of the rate of flux creep along the major hysteresis envelopes in a Y0.5Lu0.5Ba2Ca3Oy sample synthesized by a modified melt powder melt growth (MPMG) method at 25 K has been investigated. Magnetic relaxation rates depend strongly on the prior magnetic history. Calculations based on the critical state model can reproduce quite well the experimental data for magnetization when we have chosen the field exponent n = 0.3 in critical current density, Jc(Ha) = Jc0/(Ha−IM)n, where IM = Ha when 0 < H < Hc1 and (Formula presented.) when Ha ≥ Hc1. Using the field-cooled magnetization MFC data as well as the comparison of experimental and calculated M–H hysteresis loop, we estimated Hc1 = 500 Oe, p = 0, and the penetration field H∗ = 20 kOe. The apparent pinning energy was estimated as 62 meV for the remanent magnetization upon an excursion of 40 kOe.