Samples of Ca-doped material were investigated by using transmission electron microscopy. Irradiation led to the formation of stacking faults which lay on {001} planes, and extended in <100> and <010> directions. It was proposed that vacancies formed under the electron irradiation, and that relaxation then proceeded via the coalescence of 2 portions of crystal which were separated by clustered vacancies. Slippage of the bonding between two BaO layers could then occur with a displacement of 1/6[301] or 1/6[031]. Stacking faults could therefore form which had either of these displacements. The stacking faults which were formed in this way clearly lay on {001} planes, and seemed to stretch along their longitudinal direction during irradiation. Formation of the stacking faults generally began from the edge, and propagated towards the interior of the parent grain.

C.C.Lam, G.J.Shen, C.L.Fu, K.C.Hung: Superconductor Science and Technology, 1997, 10[8], 807-12