The results were presented of a computer simulation of the atomic structures of the large-angle symmetrical tilt grain boundaries, Σ5 (misorientation angles 36.87° and 53.13°) and Σ13 (misorientation angles 22.62° and 67.38°). The critical strain level εcrit criterion (phenomenological criterion) of Chisholm and Pennycook was applied to the computer simulation data in order to estimate the thickness of the non-superconducting layer enveloping the grain boundaries. The critical strain εcrit was derived from the strain field of a dislocation at the distance from its geometrical center where the lattice presumably became non-transparent to super-currents. The εcrit value determined in this way was several times higher than the estimate given in earlier work. The thickness of the non-superconducting layer enveloping grain boundaries was also estimated by using a bond-valence sum analysis. The two approaches agreed with each other. It was predicted that the symmetrical tilt grain boundary, Σ5 θ = 53.13°, would exhibit the greatest critical current across the boundary.

Atomic Structure of Large-Angle Grain Boundaries Σ5 and Σ13 in YBa2Cu3O7–δ and their Transport Properties. V.S.Boyko, A.M.Levine: Physical Review B, 2001, 64[22], 224525 (6pp)