The twin textures of 2 differently synthesized types of single crystal, which differed strongly with regard to their critical current density levels, were investigated by means of high-resolution transmission electron microscopy. One type of crystal, which had higher critical current density values and contained 1at%Sr, exhibited twin lamellae with boundaries that were decorated with many small local strain fields. It was suggested that this twin boundary structure was due to Sr doping.

Influence of Sr Doping on Twin-Wall Structure and Flux Pinning of YBa2Cu3O7-d Single Crystals. K.Saito, H.U.Nissen, C.Beeli, T.Wolf, W.Schauer, H.Küpfer: Physical Review B, 1998, 58[10], 6645-9