Elimination of Oxygenation Cracking in YBCO Bulk Superconductors

Abstract

The reasons for cracking of YBa2Cu3Oδ/Y2BaCuO5 (Y123/Y211 or YBCO) bulk single-grain superconductors are mechanical stresses, which arise in the sample during its fabrication. Two main sources of stresses appearing during fabrication were identified: the different thermal expansion coefficients of 123 and 211 phases and the dependence of 123 phase lattice parameters on the oxygen stoichiometry. As-grown YBCO bulks have low oxygen content, YBa2Cu3O6.3, are not superconducting, and must be oxygenated to form YBa…