Dislocation at a {2[Formula omitted][Formula omitted]0} low-angle grain boundary in LiNbO.sub.3

A LiNbO.sub.3 bicrystal that contains a {2 [Formula omitted] [Formula omitted]0} low-angle grain boundary with both of 2° tilt misorientation and a slight twist misorientation was fabricated, and resulting dislocation structure at the boundary was analyzed by using transmission electron microscopy (TEM) and scanning TEM. The observations revealed that two types of dislocations of b = 1/3 and b = are formed at the boundary. A 1/3 dislocation, which dissociates into two partial dislocations with a {2 [Formula omitted] [Formula omitted]0} stacking fault in between, compensates only tilt misorientation of the boundary. On the other hand, it was found that a dislocation, which dissociates into three equivalent partial dislocations with b = 1/3, has both edge and screw components in total. That is, the dislocations are formed to compensate the twist misorientation of the boundary, in addition to the tilt misorientation. It is interesting that the three partial dislocations from a dislocation are arranged in a zigzag pattern with left-right asymmetry. This special configuration is suggested to originate from the presence of stable stacking fault structure on the {2 [Formula omitted] [Formula omitted]3} plane in LiNbO.sub.3.