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.

Başoğlu, M.

In this study, three different Y358 samples were produced by the melt-powder-melt-growth (MPMG) method at different maximum grain growth temperatures of 1030 °C, 1040 °C, and 1050 °C. The differential thermal analysis (DTA), X-ray powder diffraction (XRD), magnetic levitation force, trapped magnetic field values and magnetization measurements were performed. According to the results, the highest magnetic levitation force, the highest critical current density and the highest trapped magnetic field values were obtained from the sample produced at the temperature of 1050 °C.

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.

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.

Başoğlu, M.; Yanmaz, E.

Sintered Nd-Fe-B magnets are some of the strongest magnetic materials showing magnetic properties. Blending addition is frequently performed in order to improve the magnetic properties of these materials. In this work, high-melting point Ni and low-melting point Cu were added to Nd15Fe77B8 ingot by blending. As a result of structural analysis, it was observed that 0.2 wt% Cu + Ni addition improved the structure of the material; on the other hand, excessive addition resulted in porosity. It was also observed that 0.2 wt% addition improved the magnetic properties, and Curie temperature increased with increasing addition ratio.