Structures of grain boundaries in long-chain Te crystals observed by high-resolution transmission electron microscopy.

Vacuum-deposited Te crystals, composed of endless chains of the right-handed or left-handed spiral, have been investigated by high-resolution electron microscopy with the aid of image simulation. A (010) grain boundary, which accompanies edge dislocations having an extra layer of the width of one Te chain, has been observed. A through-focal series of images reveal that it is not a reflectional nor a rotational twin boundary but a small angle grain boundary in a single crystal or an inversion twin. The lattice on one side of the boundary is shifted from that on the other side by [001]c/3 + [120]a/8, and inclined at 1.1 degrees around the c-axis of the other side. Also found between crystallites of [100] and [011] orientation is a grain boundary which is built with the (011) facets on one side of the boundary and the (211) or (0,1,10) facets on another side.