Dislocation core structures in the low-angle boundaries of Nb-doped SrTiO3 bicrystals were investigated by means of high-resolution electron microscopy. Bicrystals with tilt angles of 2, 4, 6 and 8° with respect to the  zone axis were prepared by joining 2 single crystals at 1873K. All of the boundaries consisted of a regular array of dislocations whose spacing gradually decreased with an increase in tilt angle. Except for the 2° tilt-angle boundary, the dislocation cores exhibited a dissociation from a into 2 partials of a/2 type on (100). Furthermore, 2 kinds of dislocation core structure were observed; Sr–Sr atomic columns and Ti–O atomic columns within the cores. In addition, it was found that the positioning of adjacent cores along the boundary tended to change from a linear form to a zig-zag shape as the tilt angle was increased from 4 to 8°. In the case of the linear array, dislocation core structures including Sr–Sr columns or Ti–O columns appeared alternately. In contrast, only one core structure was observed in the zig-zagged array. On the other hand, the dislocation cores in the 2°-tilt-angle boundary exhibited another type of dissociation, with a/2 or a/2 partials, which included the twist component at a tilt axis of .
Dislocation Structures of Low-Angle Boundaries in Nb-Doped SrTiO3 Bicrystals. S.Y.Choi, J.P.Buban, M.Nishi, H.Kageyama, N.Shibata, T.Yamamoto, S.J.L.Kang, Y.Ikuhara: Journal of Materials Science, 2006, 41, 2621-5