İlgi alanları

• MakaleYalnız künye2026Scopus SJRQ2/r/gumushane/13791
  Influence of holmium substitution on structural characteristics and radiation shielding parameters of YBCO (358) superconducting ceramics

  Düzgün, İbrahim; Kaya, Selim; Gül, Osman

  This study reports on the structural characterization, radiation shielding assessment, and magnetic-field response of holmium-substituted Y3-xHoxBa5Cu8O18+δ superconducting ceramics synthesized by the conventional solid-state reaction route. X-ray diffraction measurements on five compositions (x = 0, 0.75, 1.5, 2.25, 3) supported the formation of a dominant orthorhombic Y358-type matrix across the substitution range. Scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS) revealed a progressive microstructural evolution with increasing Ho content, including SEM–BEC/EDS-detectable Ho-rich inclusions consistent with Ho2BaCuO5-type secondary particles at higher substitution levels. XCOM-based mass attenuation coefficients, half-value layer, mean free path, effective atomic number, radiation protection efficiency, gamma-ray kerma coefficients, and fast-neutron removal cross-sections were calculated for all five compositions over 50–2000 keV. EGS4 Monte Carlo simulations independently verified the XCOM results for three representative compositions (x = 0, 1.5, and 3). Ho-containing specimens exhibited a significant enhancement in photon absorption near 60 keV, associated with the increased photoelectric contribution of holmium in the vicinity of its K-absorption edge. Among the full five-composition series, the x = 2.25 specimen (ρ = 5.531 g cm−3) exhibited the best calculated shielding performance across the full energy range, owing to its highest bulk density combined with substantial Ho incorporation. The x = 1.5 specimen provided the most balanced calculated radiation-attenuation and hysteretic magnetic response among the three representative compositions examined by EGS4 and M–H measurements at 20 K, retaining approximately 93% of the reference M–H hysteresis area while full substitution reduces it by roughly 67%. These findings establish a multi-parametric reference dataset for Ho-substituted Y358 ceramics and demonstrate the promise of rare-earth-engineered superconducting ceramics as multifunctional materials in radiation-intensive environments.

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• MakaleAçık Erişim2026Scopus SJRQ3/r/gumushane/13588
  Enhancing precision of low-cost detectors via machine learning for accurate mass attenuation coefficient estimation

  Düzgün, İ.; Küçük, M.A.; Kaya, S.; Çelik, N.

  Low-cost NaI(Tl) detectors are practical for gamma-ray spectrometry but their limited energy resolution can introduce systematic errors in mass attenuation coefficient measurements when scattered photons are included in the peak region. This study proposes a machine-learning correction framework that maps NaI(Tl)-derived attenuation coefficients to XCOM-based HPGe-equivalent reference values through a dimensionless correction factor. An EGS4/XCOM dataset of 756 model-development configurations, covering 18 atomic numbers, six monoenergetic photon energies, and seven collimator radii, was used to train twelve regression models and evaluate them over 60 randomized train–validation–test cycles. Sodium and Bismuth were withheld for external material-wise validation. Gaussian Process Regression with a Matérn 5/2 kernel provided the best overall testing performance. For the withheld materials, the correction reduced the mean deviation from XCOM references from 3.07% to 0.83%, supporting its use as a practical correction layer for low-cost attenuation measurements.

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• MakaleAçık Erişim2026Scopus SJRQ2/r/gumushane/13581
  Computational analysis of radiation shielding properties of BaO-modified magnesium borophosphate glasses based on WinXCOM and EGS4 Monte Carlo simulations

  Düzgün, İbrahim; Çelik, Necati; Kaya, Selim

  The increasing use of ionizing radiation in medical, industrial, and nuclear applications necessitates the development of advanced and environmentally friendly shielding materials. In this study, the gamma-ray shielding performance of BaO-modified magnesium borophosphate glasses with compositions xBaO–30MgO–10P2O5–(50−x)B2O3–10Na2O (x = 0–35 mol%) was theoretically investigated. The radiation attenuation properties were evaluated over a wide photon energy range (59.54–2000 keV) using the WinXCOM database and Monte Carlo simulations based on the EGS4 code. Key shielding parameters, including mass attenuation coefficient (μ/ρ), half-value layer (HVL), mean free path (MFP), effective atomic number (Zeff), radiation protection efficiency (RPE), and gamma-ray kerma coefficients, were determined. The results indicate that increasing BaO content enhances the attenuation capability of the glass system, particularly in the low and medium photon energy regions, due to increased density and effective atomic number. A good agreement between WinXCOM and EGS4 results confirms the reliability of the applied theoretical approaches. These findings suggest that BaO-modified magnesium borophosphate glasses are promising candidates for radiation shielding applications.

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• MakaleYalnız künye2025Scopus SJRQ2/r/gumushane/14101
  Remanent magnetization and magnetic relaxation in Bi:2223/ag tapes fabricated by the Powder-in-Tube (PIT) method at 30 K

  Düzgün, İbrahim; Çelebi, Selahattin

  In this study, the remanent magnetization and magnetic relaxation behaviour of Bi-2223/Ag superconducting tapes fabricated using the Powder-In-Tube (PIT) method were investigated. Measurements were conducted at a fixed temperature of 30 K, both under various field cycling amplitudes and in constant magnetic field conditions to analyse time-dependent magnetization. The remanent magnetization values obtained after full magnetic cycles were normalized and compared with theoretical predictions based on the extended critical state model. Additionally, magnetic relaxation curves were recorded at 30 K to evaluate flux creep characteristics. A clear logarithmic decay in magnetization was observed, indicating the coexistence of at least two distinct pinning regimes. These results contribute to a deeper understanding of flux dynamics and magnetic stability in Bi-2223/Ag PIT tapes for practical superconducting applications.

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• MakaleYalnız künye2025Scopus SJRQ3/r/gumushane/11700
  Impact 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.

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• DüzeltmeAçık Erişim2022Scopus SJRQ3/r/gumushane/11894
  Correction to: The First Measurement for Mass Attenuation Coefficients, Effective Atomic Numbers, and Electron Densities of Y123 and Y358 High-Temperature Superconductors (HTS) for the Energies from 46.6 to 1332 keV (Journal of Superconductivity and Novel Magnetism, (2021), 34, 3, (695-703), 10.1007/s10948-020-05771-0)

  Düzgün, İbrahim

  The original version of this article contained a mistake. Thus this erratum is presented to fix this error. The section “Funding” should read as follows: This study was funded by the Grant-in-Aid for Gümüşhane University Research Fund (GÜBAP), from the Gümüşhane University (Project Number: 13.F5120.02.1).

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• MakaleYalnız künye2021Scopus SJRQ3/r/gumushane/14651
  The First Measurement for Mass Attenuation Coefficients, Effective Atomic Numbers, and Electron Densities of Y123 and Y358 High-Temperature Superconductors (HTS) for the Energies from 46.6 to 1332 keV

  Düzgün, İbrahim

  Y123 and Y358 high-temperature superconductor phases have experimental mass attenuation coefficients (MAC) determined at 46.5, 81, 122, 302, 356, 383, 662, 1173, and 1332 keV photon energies. The experimental values have been compared with theoretical values acquired employing the XCOM software and database. It has been observed that the theoretical and the empirical results were in perfect agreement. Also, it has been seen that the comparison of the MACs for all specimens examined with the corresponding photon energies complies with the exponential absorption law. The effective atomic numbers (Zeff) and electron densities (Nel) of Y123 and Y358 superconducting phases in different energy ranges have determined experimentally and theoretically. The Y358 superconductor specimen is a relatively better absorber than the Y123 between 40 and 100 keV.

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• MakaleYalnız künye2021Scopus SJRQ3/r/gumushane/12896
  Specification 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.

  AtıfScopus10·WoS10·OpenAlex10

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• MakaleYalnız künye2020Scopus SJRQ3/r/gumushane/14880
  Comparative 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.

  AtıfScopus6·WoS5·OpenAlex6

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• MakaleAçık Erişim2018Scopus SJRQ3/r/gumushane/15326
  The investigation of the lattice strains and crystallite sizes of Y358 and Y123 high-temperature superconductors

  Duzgun, Ibrahim

  In this study, the Y358 phase, the newest high-temperature superconductor member of the yttrium barium copper oxide family, was produced using the solid-state reaction technique. The Y358 superconductor exhibited the Meissner effect at low temperature (77 K). The X-ray diffraction spectra indicated that the crystal structure was almost identical to that of Y123, but with some impurity peaks. An X-ray peak broadening analysis was applied to determine the lattice strain, and the medial crystallite size was calculated perpendicular to the surface of the superconductor specimens. As a result of the analyses, it was determined that the crystallite size of the Y358 superconductor was about 1.125 times larger than that of the Y123 superconductor.

  AtıfScopus12·WoS9·OpenAlex12

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