TEM study of 〈110〉-type 35.26° dislocations specially induced by polishing of SrTiO3 single crystals

The dislocations created by mechanical polishing of SrTiO3 (100) single crystals were investigated by means of transmission electron microscopy (TEM) techniques combined with scanning TEM (STEM) techniques. A high density of dislocations was observed in the surface layer with a thickness of about 5 μm. These dislocations were found to be straight and highly aligned along the 〈111〉 directions. In most cases they appear in pairs or as a bundle. The nature of the dislocations was determined as mixed 〈110〉-type with the line vector t=〈111〉. They are 〈110〉-type 35.26° dislocations. The isolated 〈110〉-type 35.26° dislocations possess a compact core structure with a core spreading of ~0.5 nm. Dissociation of the dislocation occurs on the {1−10} glide plane, leading to the formation of two b=a/2〈110〉 partials separated by a stacking fault. The separation of the two partials was estimated to be 2.53±0.32 nm based on a cross-correlation analysis of atomic-resolution images. Our results provide a solid experimental evidence for this special type of dislocation in SrTiO3. The high density of straight and highly 〈111〉-orientated dislocations is expected to have an important influence on the anisotropy in electrical and mass transport properties.