扫描透射电子显微镜
位错
暗场显微术
电子能量损失谱
不对称
晶界
光学
凝聚态物理
扭转
散射
芯(光纤)
电子
透射电子显微镜
材料科学
分子物理学
化学
物理
显微镜
几何学
结晶学
微观结构
量子力学
数学
作者
L. Fitting,Stefan Thiel,A. Schmehl,Jochen Mannhart,David A. Muller
标识
DOI:10.1016/j.ultramic.2006.04.019
摘要
A screw dislocation network at the low-angle SrTiO3/Nb:SrTiO3 twist grain boundary has been analyzed by annular dark field (ADF) imaging and spatially resolved electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM). The cores of one set of dislocations running parallel to the beam direction appear dark in the ADF STEM images. EELS on the dislocation core reveals a reduced Sr/Ti ratio compared to the bulk suggesting Sr-deficient cores. The second set of dislocations, orthogonal to the latter, is imaged by its strain field using low-angle annular dark field (LAADF) imaging. Multislice image simulations suggest channeling of the electron probe on the atomic columns for small tilts, theta < 1 degree, where the Sr columns act as beam guides. Only for larger tilts is the channeling effect strongly reduced and the fringe contrast approaches the value predicted by a purely incoherent imaging model. Ti-L(2,3) EELS across the dislocation core shows an asymmetry between the EELS and the ADF signal which cannot be explained by the geometry or beam broadening. This asymmetry might be explained by an effective nonlocal potential representing inelastic scattering in EELS.
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