The boundaries in Ag-sheathed tapes were investigated by using transmission electron microscopy. A typical feature of the tapes was a colony structure which consisted of grains with a common c-axis. The grains within a given colony were piled up along the common c-axis, and were separated by [001] twist boundaries. It was found that the rotation angle of these twist boundaries took several definite values. Boundaries were formed between colonies which had c-axes that were slightly tilted with respect to each other. Two basic types of colony boundary were observed. One type was the small-angle c-axis tilt boundary, and the other type was the edge-on c-axis tilt boundary.

D.P.Grindatto, B.Hensel, G.Grasso, H.U.Nissen, R.Flükiger: Physica C, 1996, 271[1-2], 155-63