Special grain boundaries in YBa2Cu3O7-x

Abstract

Much attention has recently been paid to the characterization of twin boundaries in YBa2Cu3O7-x (YBCO). However, in polycrystalline samples other high-angle grain boundaries may have a much more significant effect on, not only the superconducting behavior, but also the chemical and mechanical stability of the material. In the present study, attention has therefore also been focussed on several types of low-angle and high-angle grain boundaries. Such boundaries are frequently found in thin films of this material which are grown on {001}-oriented, single-crystal yttria-stabilized zirconia (YSZ) or magnesium oxide by electron beam co-evaporation of the metals in an oxygen atmosphere. The fact that over most of the substrate these films are oriented epitactically with respect to the zirconia substrate means that these high-angle grain boundaries can be characterized in a relatively routine manner using selected-area diffraction. The high-angle boundaries observed in this study include those produced by 23.5°, 29°, and 45° rotations about [001] and 90° rotations about [100] or [010]. These boundaries are compared to special high-angle grain boundaries in cubic materials.