Patterns looking like the polysynthetic twin structure of the YBa2Cu3O7-δ compound appeared in high magnification secondary electron images, obtained by scanning electron microscopy, on both cleaved and polished samples. The characteristics in common between these patterns and the twins usually observed by optical or transmission electron microscopy were considered (a wide extension, quite good homogeneity at the picture scale, presence at different topographical levels, the orientation along two nearly perpendicular directions, and the presence of tip endings). In order to determine the exact nature of these features, a comparison of images of the same areas obtained by transmission electron microscopy and scanning electron microscopy was presented. This revealed that the alternate bright and dark strips observed in secondary electron scanning electron microscopy images were clearly twin domains.

Characterization of the Twin Structure of TSMTG-Processed YBa2Cu3O7-δ Ceramics by Scanning Electron Microscopy. F.Delorme, C.Harnois, I.Monot-Laffez: Superconductor Science and Technology, 2004, 17, 692-5