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    Infiltration effects on (RE)123 superconductors
    (Physical Society of the Republic of China, 2019) Karaca İ.; Şimşek N.; Özen S.; Güler M.T.
    We produced RE-123 infiltrated by Sm123 superconductors by the melt growth method. The samples have been investigated in terms of X-ray diffraction (XRD)analysis, AC susceptibility, levitation force, and a magnetic stiffness calculation. The X-ray diffraction analysis showed that the Sm123 and Y123 phases were insufficiently grown at the selected sintering temperature of 1040 °C. The transition temperature of the IP Sample is 94.28 K from the AC Susceptibility (at 1 KHz and 4 Oe applied AC field)measurement. The magnetic stiffness was calculated using our newly designed vertical magnetic levitation force measurement system. It has a Nb-Fe-B permanent magnet (~0.5T)at 77 K with the Zero Field Cooled process. The magnetic stiffness was calculated using the data of the levitation force. The descending experimental results showed that the most significant F 0 was contained in the sample I5 (F 0 = 9.034 N)and the largest constant b value was determined in the sample IP (b = 0.3320 mm -1 ). But in the ascending results, the most significant F 0 is 8.604 N, and the largest constant b is 0.3047 mm -1 , both calculated in the IP sample. Considering the oxygen content effects on the magnetic stiffness, one can infer that it has been positively affected by an increase in the Sm123 infiltration. These results indicatethat the produced samples could be applied to bearing systems, magnetic sensors and other technological applications. © 2019 The Physical Society of the Republic of China (Taiwan)
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    Influence of Tin doping on the Sm123 superconducting ceramics
    (Springer New York LLC, 2019) Karaca İ.; Ünlüer Ş.
    We produced the samples that consist of the nominal composition as Sm 1.46 Ba 1.54-x Sn x Cu 3.2 O y (x = 0.35; 0.55; 0.75 and 0.95) by the melt growth method. We investigated Sn-dopant effects regarding differential scanning calorimetry, scanning electron microscope, X-ray powder diffraction and levitation force. The X-ray powder diffraction diagrams show many Sm211 phases in the Sn-doped samples. The lattice structures belong to the orthorhombic and tetragonal unit cells for the Sn-free and Sn-doped samples, respectively. We achieved the reduction of the grain size and the percentage of the orthorhombic phase with Sn doping. The SEM images of Sn-doped samples reveal to the reduction of the grain size. The reason of phase transformation is suspected to be related to the evolution of the c-lattice parameter. It is well-known that oxygen content also causes the phase transformation of the RE123. The a, b, and c-lattice parameters correspond to the unit cell closely matched to the well-known Sm123 values in the literature. The orthorhombic (123) phase in the matrix increases later, even if it makes smaller initially in terms of grain size. In this study, the reduction of the grain size confirms the increasing of tetragonal (211) phase in the matrix. This indicates that the (211) phase has been filtered in the matrix. Namely, the Sn-dopant effect induces the increase of Sm211 phase, in this way the phase transformation occurs in the matrix. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.