Improved Uniformity of Superconducting Properties in GdBCO Superconductor Bulk with a Buffer Layer

Y. Zhanga, Y.F. Zhanga, S.Y. Shena, W.L. Wanga, G.J. Ruana, Y. Lia, J.Y. Zhanga, P.H. Zhanga, Z.W. Loua, L. Penga, D.F. Zhoub aCollege of Mathematics and Physics, Shanghai University of Electric Power, 1851 Hucheng Ring Road, New Pudong District, Shanghai 201306, People's Republic of China bShanghai Key Laboratory of High Temperature Superconductors, Shanghai University, 99 Shangda Road, Baoshan District, Shanghai 200444, People's Republic of China

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Uneven distribution of local superconducting properties can significantly impact the overall performance of REBa2Cu3O7-δ (REBCO or RE123) superconductor bulks. Through the modified top-seeded melt-texture growth method, we successfully prepared single-domain GdBa2Cu3O7-δ (GdBCO) superconductor bulks with (bulk A) and without (bulk B) a buffer layer, and investigated the relationship between superconducting properties and microstructure of the bulks in detail. Measurement results show that the maximum trapped flux density value of bulk A is 0.48 T, and that of bulk B is 0.5 T. The distribution of transition temperature (TC) and critical current density (JC) becomes more uniform along the c- and a/b-directions in bulk A. In bulk B, i.e., without a buffer layer, the JC varies greatly at different locations due to microstructural inhomogeneity. The buffer layer acting as a large seed can increase the growth rate, resulting in a decrease in the size and an increase in the concentration of Gd2BaCuO5 (Gd211) particles in the microstructure according to pushing/trapping and coarsening theory. The corresponding JC performance shows a certain improvement in all fields, which suggests that the buffer layer has a positive effect on the spatial uniformity of superconducting properties in superconductor bulks.

DOI:10.12693/APhysPolA.146.195 topics: GdBCO superconductor bulk, top-seeded melt-texture growth (TSMG) method, critical current density, buffer layer