A study was made of the electronic structures of YBa2Cu3O7 [010]([001]) tilt and twist grain boundaries by using first-principles density functional theory. The Σ3(010)/[010](90°) twist grain boundary had the lowest grain-boundary energy (-122.6mJ/m2). Across this interface, the (001)-CuO2 layers on one side linked almost perfectly to the (100)-Cu3O5 layers on the other side. The negative grain-boundary energy between such thin YBa2Cu3O7 [010] films implied that the special one-dimensional superlattice structure along the [010] direction was more stable than a perfect YBa2Cu3O7 lattice. The Σ3 tilt grain boundary had an energy of 167mJ/m2. The Σ5 twist boundaries had energies of 770.1 to 1229mJ/m2. The Σ5 tilt boundaries had energies of 1294 to 1966mJ/m2.

Atomic and Electronic Structures of YBa2Cu3O7 [001], [010] Tilt and Twist Grain Boundaries. W.Fan, Z. Zeng: Superconductor Science and Technology, 2014, 27[2], 025007