Analyses of the grain boundary misorientation and oxygen content of bulk processed YBa2Cu3O7-δ

The grain boundary misorientation distribution of 203 grain boundaries in bulk processed high Tc superconductor YBa2Cu3O7-δ with five processing conditions;, was studied. Two complementary analytical approaches, Grain Boundary Misorientation Distribution (GBMD) from the random description, using a hypothesis test and χ2 analysis, and Grain Boundary Character Distribution (GBCD), using the Coincidence Site Lattice (CSL) model, were applied. The GBMD and GBCD both showed grain boundary evolution departing from a random distribution above 935 C processing temperature. The GBCD analyses indicated an approximately linear increase in the population of CSL-related boundaries, among which the tetragonal CSL (c/a ≠ 3) boundaries grew in the same trend while orthorhombic boundaries (c/a = 3) became stagnated. The results from comparing the corresponding GBCD and volume averaged Jc for each batch indicated that the tetragonal CSL boundaries were oxygen deficient and accounted for, among other current limiting factors, lower current carrying ability