Defects in the para-electric phases of BaTiO3 doped with Bi2O3 were analyzed by transmission electron microscopy under two-beam conditions. (111) twin structures were characterized by selected area diffraction and bright-field images. The orientation relationships of the (111) twins were determined by using stereograms. Lamella-twinned crystallites included in the para-electric phases were found in this system. Pure wedge fringes were analyzed in these grains by using electron diffraction and imaging techniques. Double diffraction was observed in the overlapped regions of the matrix and the micro-twin in the [113] direction, and high-density dislocation loops were seen in some grains. Weak-beam dark-field microscopy techniques were used to observe the dislocation loops, which predominately lay on {100} crystal planes with Burgers vectors a<100>, and were found to be pure edge dislocations. Some dislocations were transformed into crystallographic shear planes.

Investigation of Lamella-Twinned Crystallites and Dislocations in Paraelectric Phases of Bi2O3-Doped BaTiO3. Q.Feng, C.J.McConville: Journal of the American Ceramic Society, 2004, 87[12], 2247