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    Influence of Gd Substitution on Structural, Magnetic and Magnetocaloric Properties in (La0.8Gd0.2)0.85Ag0.15MnO3 Perovskite Manganite System
    (2018) Ekicibil, Ahmet; Ayaş, Ali Osman; Akyol, Mustafa
    In this paper, the effect of Gd substitution with La on structural, magnetic and magnetocaloricproperties in (La0.8Gd0.2)0.85Ag0.15MnO3 manganite sample prepared by sol-gel method has been studied. Thecrystal properties have been investigated by x-ray diffraction technique that shows the sample is inrhombohedral structure with R3?c space group. In addition to this structure, small amount of reflections belongsto GdMn2O5 phase is detected. Scanning electron microscope images show that the sample is constituted fromsquare shaped grains. Energy dispersive x-ray spectroscopy analysis shows that the sample includes all expectedelements. The sample exhibits magnetic phase transition from ferromagnetic to paramagnetic phase at around149 K temperature. Applied field dependence of magnetization under isothermal process M(H) shows that thenature of the phase transition is second order and maximum magnetic entropy change (-?SM) value calculatedfrom M(H) curves is found as 1.73 J/kgK under 50 kOe external magnetic field change.
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    Öğe
    Transport Properties of Superconducting Materials
    (Springer Nature, 2022) Ekicibil, Ahmet; Karadağ, Faruk; Çetin, Selda Kılıç; Ayaş, Ali Osman; Akça, Gönül; Akyol, Mustafa; Kaya, Doğan
    In superconducting materials, a phase transformation occurs at critical transition temperature, Tc, and they show zero resistivity below Tc. The relation between zero resistivity and superconducting properties is an interesting and important issue to understand the mechanism of superconductivity especially for high-Tcsuperconductors (HTSCs). To determine the behavior of superconducting materials under an applied magnetic field, many remarkable studies that have been conducted due to their great technological and industrial importance. The magnetic field causes a change in the transition temperature, the width of resistance transition and activation energy of superconducting materials. Energy dissipation is one of the important obstacles to obtain superconducting material with desired properties for practical industrial applications. Thus, some important models that make an explanation about the dissipation mechanism have been explained and interpreted. The critical current density has been discussed with early and recent models, experimental methods, and recent studies on HTSCs. In addition, a transverse voltage difference (the Hall voltage) can be observed in superconductor materials, especially in HTSCs, under perpendicular magnetic fields. But, the sign of Hall voltage becomes opposite to the ordinary Hall effect. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022.