Using a 300keV transmission electron microscope equipped with a field-emission gun, a study was made of grain boundaries by forming a coherent electron probe 100 to 200µm above the specimen and observe in the diffraction mode the angular distribution of the transmitted electrons within the convergent beam disks. A study was made of Bi-based high-temperature superconductors containing stacking faults and twist grain boundaries with accompanying displacements perpendicular to the boundary plane. Strong intensity oscillation from the planar faults was observed even when they were viewed edge-on, in agreement with model calculations. At twist boundaries, a rigid-body translation was observed normal to the boundaries which was as large as 0.03nm, and determined the displacement vector associated with the addition or subtraction of one bilayer of (CuO2 + Ca) to be 0.320nm for the intrinsic and extrinsic layers in Bi2Sr2CaCu2O8, as well as for the intrinsic layer in Bi2Sr2Ca2Cu3O10. The possibility of determining the profile of the inner potential across grain boundaries by using this coherent electron probe was also considered.

Quantitative Analysis of Twist Boundaries and Stacking Faults in Bi-Based Superconductors by Parallel Recording of Dark-Field Images with a Coherent Electron Source. L.Wu, Y.Zhu, J.Tafto, D.O.Welch, M.Suenaga: Physical Review B, 2002, 66[10], 104517 (12pp)