Special grain boundaries in YBa2Cu3O7

The orientation distribution produced in strings of YBa2Cu3O7−x often referred to as 123, crystals produced from a melt is not random. The individual crystals are kinematically free to rotate during the coalescence process and it is found that coincidence site lattice misorientations are selected. This observation suggests that grain boundaries in 123 have structures related to those in other crystalline materials.