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Research on precision‐calibration techniques for selected area electron diffraction patterns of pyrocarbon
Author(s) -
Qi Lehua,
Li Miaoling,
Li Hejun,
Xu Guozhong,
Wang Chuang
Publication year - 2009
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/jemt.20658
Subject(s) - selected area diffraction , gaussian , diffraction , gaussian function , ellipse , materials science , dynode , electron diffraction , optics , chemistry , physics , mathematics , geometry , computational chemistry , photomultiplier , detector
The key techniques for determining orientation angle (OA) and interlayer space ( d 002) of pyrocarbon were investigated by analyzing selected area electron diffraction (SAED) patterns. A series of algorithms, which mainly include the five‐point center‐determined technique, the integral factor for the ellipse detection, the background subtraction operation and the Gaussian multipeak fitting algorithm, were designed for intensity sampling, data correction, and data fitting. The contribution ratio of the reflection intensity to the average d 002 was considered. The algorithms were programmed and applied to evaluate SAED patterns of pyrocarbon in C/C composites by chemical vapor infiltration. Results showed that the proposed techniques can be effectively used to measure various SAED patterns, with a beam stop image or not, of pyrocarbon. The azimuthal intensities along the (002) arcs essentially obey the Gaussian distribution, although this is not obvious for the lower textural pyrocarbon. It is necessary for accurate OA to use the Gaussian multipeak fitting algorithm. Microsc. Res. Tech., 2009. © 2008 Wiley‐Liss, Inc.