Dislocation structure at a f1210g=h1010i low-angle tilt grain boundary in LiNbO3

LiNbO3 is a ferroelectric material with a rhombohedral R3c structure at room temperature. A LiNbO3 bicrystal with a f1210g=h1010i 1 low-angle tilt grain boundary was successfully fabricated by diffusion bonding. The resultant boundary was then investigated using highresolution TEM. The boundary composed a periodic array of dislocations with b 1⁄4 1=3h1210i. They dissociated into two partial dislocations by climb. A crystallographic consideration suggests that the Burgers vectors of the partial dislocations should be 1=3h0110i and 1=3h1100i, and a stacking fault on f1210g is formed between the two partial dislocations. From the separation distance of a partial dislocation pair, a stacking fault energy on f1210g was estimated to be 0.25 J/m on the basis of isotropic elasticity theory.