Lozano J G, Yang H, Guerrero-Lebrero M P, D'Alfonso A J, Yasuhara A, Okunishi E, Zhang S, Humphreys C J, Allen L J, Galindo P L, Hirsch P B, Nellist P D
Department of Materials, University of Oxford, OX1 3PH Oxford, United Kingdom.
Departamento de Ingeniería Informática, CASEM, Universidad de Cadiz, Polígono Rio San Pedro s/n, 11510 Puerto Real (Cadiz), Spain.
Phys Rev Lett. 2014 Sep 26;113(13):135503. doi: 10.1103/PhysRevLett.113.135503. Epub 2014 Sep 24.
We demonstrate that the aberration-corrected scanning transmission electron microscope has a sufficiently small depth of field to observe depth-dependent atomic displacements in a crystal. The depth-dependent displacements associated with the Eshelby twist of dislocations in GaN normal to the foil with a screw component of the Burgers vector are directly imaged. We show that these displacements are observed as a rotation of the lattice between images taken in a focal series. From the sense of the rotation, the sign of the screw component can be determined.
我们证明，像差校正扫描透射电子显微镜具有足够小的景深，能够观察晶体中与深度相关的原子位移。与具有伯格斯矢量螺旋分量且垂直于箔材的氮化镓中位错的埃舍尔比扭转相关的深度相关位移被直接成像。我们表明，这些位移在聚焦系列拍摄的图像之间表现为晶格的旋转。根据旋转方向，可以确定螺旋分量的符号。
