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International Conference on Superconductivity and Magnetism, Muğla, Turkey, 26 April - 03 May 2025, pp.690, (Summary Text)
This study investigated hollow single crystal Top Seeded Melt Growth (TSMG) YBa2Cu3O7-x (YBCO or Y123) samples welded with Ag added TSMG YBCO solder materials produced using NdBCO/YBCO/MgO thin film seeds. Three main samples with the composition of Y123 + 25 wt.% Y211 and one solder material with the composition of Y123 + 25 wt.% Y211 + 20 wt.% Ag2O were produced by the TSMG method. In order to increase the dimensions of the bulk YBCO superconductor, two slices of the solder material and the main samples were stacked on top of each other with the c-axis parallel and welded at 1030 °C.
X-ray diffraction patterns and polarized optical photographs were taken to determine the structural properties of the samples. A preferential orientation in the c-axis was observed and a good connection was obtained in the welding region. Low temperature resistance was made for the specimens taken from the welding region. A sharp superconducting transition occurred at 0 T around 93 K for W-ab and W-bc specimens welding regions. The dependence of the effective activation energy U of the flux pinning on the magnetic field and the temperature of the sample was determined using the Arrhenius activation energy law from the resistivity curves. The W-bc was observed to have higher activation energy in 0T and 7T magnetic fields. This means that the movement of the pinning centers of the W-bc is more difficult than the other specimens with the increasing magnetic field. The dependency of activation energy on the magnetic field is proportional to constant α, which is called the magnetic power constant of activation energy. These constant values showed that planar defects are considered to be effective for W-bc.
Acknowledgements
This study was supported by Scientific and Technological Research Council of Turkey (TUBITAK) under the Grant Number 219M281. The authors thank to TUBITAK for their supports.