Lattice distortion of a (0001) twin constrained by grain boundaries in a p-type (bi,Sb)2Te3 alloy during three point bending deformation

Twinning, which is directly related to partial dislocation, has been extensively observed as a main plastic deformation mechanism in crystals. Generally, there are no other lattice defects inside the twins. By using transmission electron microscopy (TEM), we document, for the first time, the presence of lattice distortion of a (0001) twin within a deformed p-type (Bi,Sb)2Te3 alloy. Atomic scale analyses for the characteristics and mechanism of this lattice distortion of a (0001) twin have been systematically carried out with high resolution TEM (HRTEM) and geometric phase analysis (GPA) tool. Results reveal that the mechanism of lattice distortion of a (0001) twin can be attributed to the twisting deformation occurred near the twin boundaries under the effect of an external torque. Further, we constructed structure models of the lattice distortion of a (0001) twin based on HRTEM and GPA analysis.