HIGH-RESOLUTION DIFFRACTION STUDIES OF MICROSTRUCTURE IN YBA2CU3O7-DELTA

High resolution powder diffraction has revealed that the separation of twins can be approximately modelled from hkI reflections through the analysis of line breadths. A bulk average twin separation was found to be of the order of 500 angstrom. Analysis of hhI line breadths indicates that a fault occurs every 1300 angstrom in the (110) direction. Single crystal X-ray diffraction (XRD) analysis shows that these faults are likely to occur along the direction where the (110) planes are coherent with the twin plane. Single crystal XRD analysis also demonstrated the relationship between twin colonies of opposite orientation. Further analysis revealed that low angle boundaries are likely to exist within a crystal. These low angle boundaries are probably between domains that are some hundreds of microns in size.