Quantitative HRTEM and its application in the study of oxide materials
Chun-Lin Jia(贾春林)1,2,3, Shao-Bo Mi(米少波)3, Lei Jin(金磊)1
1 Ernst Ruska-Centre(ER-C) for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany; 2 School of Microelectronics, Xi'an Jiaotong University, Xi'an 710049, China; 3 State Key Laboratory for Mechanical Behaviour of Materials, Xi'an Jiaotong University, Xi'an 710049, China
Abstract On the basis of a state-of-the-art aberration-corrected transmission electron microscope, the spherical aberration coefficient CS of the objective lens can be tuned to either a positive or a negative value. The use of a negative value of CS combined with an overfocus setting of the objective lens leads to the development of the negative CS imaging (NCSI) technique. Images obtained using the NCSI technique show superior contrast and signal intensity at atomic column positions than the corresponding positive CS images, especially for weakly scattering oxygen columns that are in close proximity to strongly scattering cation columns in oxides. Based on the images obtained under the NCSI condition, quantification of the image contrast allows measurements of the atom positions with a precision of a few picometers and the local chemistry on atomic scale. In the present review, we discuss firstly the benefits of the NCSI technique in studies of oxide materials, and then show a procedure for quantitative analysis of the image based on the absolute value of contrast. In the last part, examples are given for the application of the quantitative high-resolution transmission electron microscopy (HRTEM) to the study of electric dipoles of oxide ferroelectrics and atomic-scale chemistry of interfaces.
Fund: Project supported by the National Natural Science Foundation of China (Grant Nos.51390472 and 51471169) and the National Basic Research Program of China (Grant No.2015CB654903).
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