球差校正电镜技术及应用进展讲座.ppt

未被校正的系统的电子波的相位移，依赖于照明平面波的入射方向，照明 束的倾斜会改变相位移。 （a）未被校正的系统衍射图表，方位角以π/6为单位在0-2π之间变化。 （b）球差校正并对中合轴后的衍射图表。可以看出电子束倾斜角变化，衍射图的形状相同，表明消球差特性。 4.球差校正电镜的应用 Structure image of a GaAs crystal viewed along a 110- direction. The crystal was oriented by means of a standard Philips ± 40 ℃ double-tilt holder. The atom positions Appear light on a dark background. Max. Haider, Harald Rose, Stephan Uhlemann, Eugen Schwan, Bernd Kabius,Knut Urban, Ultramicroscopy 75 (1998) 53-60 (1)研究原子结构 1nm (a’)∑3{111} twin boundary in BaTiO3; (b’) Transversal inversion polarization-domain wall in ferroelectric PZT; HAADF images in STEM, AlN in [–2,1,1,0] projection. Si along a crystallographic [112] direction. Knut W. Urban, Science 321, 506 (2008); P. D. Nellist,Chisholm, N. Dellby,O. L. Krivanek, Science (2004); (a’) (b’) Structure images of an epitaxial Si(111)/CoSi2 interface demonstrating the production of image artefacts by the effect of contrast delocalization due to spherical aberration. Images (a) and (b) were taken in the uncorrected microscope at Scherzer defocus and defocus of least confusion, respectively. Image(c), taken in the aberration-corrected microscope at Scherzer defocus, does not show any contrast delocalization (Cs=0.05 mm). (2) 界面观察 （3）球差电镜对轻元素（H，Li等）的分辨 （a）初始LiFePO4沿[010]方向的环形明场像（ABF），其中黑色衬度代表原子，在ABF像中 锂离子（黄圈）清晰可见。（b）完全充电状态，红圈代表锂离子脱出的位置。（c）部分 充电状态，黄圈代表锂离子保留的位置。锂离子隔行脱出“阶”的现象呈现出来。这是首 次在部分充电的LiFePO4中观测到了锂离子的隔行脱出，类比于石墨中存在的“阶”的现象。 Lin Gu，Chang bao Zhu, Hong Li, Yan Yu, Chilin Li, Susumu Tsukimoto et al， J. Am. Chem. Soc. 2011 (a) Schematic of the annular-bright-field (ABF) imaging geometry a. Crystal structure of YH2 viewed from the [010] crystallographic direction. The individual yttrium- and hydrogen-atom columns distinguishably appear along the [010] projection. b. Faint but distinct dark-dot contrast can be recognized at the hydrogen-atom column positions in the ABF image. Simulated images are inset in images and the YH2 unit-cell projection is overlaid in b. Experime