@article{MTMT:1177893, title = {Electron diffraction based analysis of phase fractions and texture in nanocrystalline thin films, Part I: Principles}, url = {https://m2.mtmt.hu/api/publication/1177893}, author = {Lábár, János}, doi = {10.1017/S1431927608080380}, journal-iso = {MICROSC MICROANAL}, journal = {MICROSCOPY AND MICROANALYSIS}, volume = {14}, unique-id = {1177893}, issn = {1431-9276}, abstract = {A method for phase analysis, similar to the Rietveld method in X-ray diffraction, was not developed for electron diffraction (ED) in the transmission electron microscope (TEM), mainly due to the dynamic nature of ED. Nowadays, TEM laboratories encounter many thin samples with grain size in the 1-30 nm range, not too far from the kinematic ED conditions. This article describes a method that performs (semi) quantitative phase analysis for nanocrystalline samples from selected area electron diffraction (SAED) patterns. Fractions of the different nanocrystalline components are determined from rotationally symmetric ring patters. Both randomly oriented nanopowders and textured nanopowders, observed from the direction of the texture axis produce such SAED patterns. The textured fraction is determined as a separate component by Fitting the spectral components, calculated for the previously identified phases with a priori known structures, to the measured distribution. The Blackman correction is applied to the set of kinematic diffraction lines to take into account dynamic effects for medium grain size. Parameters of the peak shapes and the other experimental parameters are refined by exploring the parameter space with the help of the Downhill-SIMPLEX. Part I presents the principles, while future publication of Parts II and III will elaborate on current implementation and will demonstrate its usage by examples, respectively.}, year = {2008}, eissn = {1435-8115}, pages = {287-295}, orcid-numbers = {Lábár, János/0000-0002-3944-8350} } @article{MTMT:1177785, title = {Consistent indexing of a (set of) single crystal SAED pattern(s) with the ProcessDiffraction program}, url = {https://m2.mtmt.hu/api/publication/1177785}, author = {Lábár, János}, doi = {10.1016/j.ultramic.2004.12.004}, journal-iso = {ULTRAMICROSCOPY}, journal = {ULTRAMICROSCOPY}, volume = {103}, unique-id = {1177785}, issn = {0304-3991}, abstract = {A computer program called "ProcessDiffraction" helps indexing a set of single crystal selected area electron diffraction (SAED) patterns by determining which of the presumed structures can fit all the measured patterns simultaneously. Distances and angles are measured in the digitalized patterns with a graphical tool by clicking on the two shortest non-collinear vectors (spots), using user-supplied calibration data. Centers of the spots and center of the pattern are optionally refined by the program. Suggested individual indexing solutions (consistent with an assumed unit cell) are listed by the program for each pattern. Simulated patterns are also consulted to check if the shortest calculated distances coincide with measured ones. Common solutions for the set are selected by checking the angles between the suggested zone axes against the angles between the experimental goniometer settings. The indexing process is manually controlled by selecting the candidate structures (one-by-one) for indexing and by specifying the tolerances for d-values, plane angles and zone angles. Patterns of any crystal system can be indexed successfully. Although error bars are larger in electron diffraction than in X-ray diffraction (XRD), frequently, many unrelated indexings are possible for any one electron diffraction pattern (irrespective of the indexing method), a set of SAED patterns can generally be indexed unambiguously, i.e. the three-dimensional reciprocal space can be identified correctly. Two other tools also help planning tilting experiments: zones along a plane can be listed (with their angles extended from a pre-selected zone in that plane) and zones lying at a given angle (specified with a tolerance) from a zone can also be identified (as they are situated between two cones). Another tool searches the XRD database directly either for advice on possible structures for a composition or to help calibration. (c) 2004 Elsevier B.V. All rights reserved.}, year = {2005}, eissn = {1879-2723}, pages = {237-249}, orcid-numbers = {Lábár, János/0000-0002-3944-8350} } @article{MTMT:1177519, title = {A tool to help phase identification from electron diffraction powder patterns}, url = {https://m2.mtmt.hu/api/publication/1177519}, author = {Lábár, János}, journal-iso = {MICROSC ANAL UK ED}, journal = {MICROSCOPY AND ANALYSIS UK EDITION}, volume = {75}, unique-id = {1177519}, issn = {0958-1952}, year = {2002}, pages = {9-11}, orcid-numbers = {Lábár, János/0000-0002-3944-8350} } @CONFERENCE{MTMT:1169478, title = {"ProcessDiffraction": A computer program to process electron diffraction patterns from polycrystalline or amorphous samples}, url = {https://m2.mtmt.hu/api/publication/1169478}, author = {Lábár, János}, booktitle = {Proceedings of the 12th European Congress on Electron Microscopy}, unique-id = {1169478}, year = {2000}, pages = {I 379-I 380}, orcid-numbers = {Lábár, János/0000-0002-3944-8350} }