Prototype symmetry of the ferroelastic superconductor Y-Ba-Cu-O.

Abstract

The question of the prototype symmetry of Y-Ba-Cu-O is reassessed in the light of recent electron-diffraction evidence for the existence of a homologous series of ordered phases in this material. It is argued that the apparaently incompatible data regarding the orientations of the various ferroelastic domain walls found in it can be explained by postulating that walls other than the commonly observed {110} walls must be occurring in regions of a specific oxygen stoichiometry only.