TY  - JOUR
AU  - Lábár, János
TI  - Electron diffraction based analysis of phase fractions and texture in nanocrystalline thin films, Part I: Principles
JF  - MICROSCOPY AND MICROANALYSIS
J2  - MICROSC MICROANAL
VL  - 14
PY  - 2008
IS  - 4
SP  - 287
EP  - 295
PG  - 9
SN  - 1431-9276
DO  - 10.1017/S1431927608080380
UR  - https://m2.mtmt.hu/api/publication/1177893
ID  - 1177893
AB  - 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.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Lábár, János
TI  - Consistent indexing of a (set of) single crystal SAED pattern(s) with the ProcessDiffraction program
JF  - ULTRAMICROSCOPY
J2  - ULTRAMICROSCOPY
VL  - 103
PY  - 2005
IS  - 3
SP  - 237
EP  - 249
PG  - 13
SN  - 0304-3991
DO  - 10.1016/j.ultramic.2004.12.004
UR  - https://m2.mtmt.hu/api/publication/1177785
ID  - 1177785
AB  - 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.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Lábár, János
TI  - A tool to help phase identification from electron diffraction powder patterns
JF  - MICROSCOPY AND ANALYSIS UK EDITION
J2  - MICROSC ANAL UK ED
VL  - 75
PY  - 2002
SP  - 9
EP  - 11
PG  - 3
SN  - 0958-1952
UR  - https://m2.mtmt.hu/api/publication/1177519
ID  - 1177519
LA  - English
DB  - MTMT
ER  - 

TY  - CONF
AU  - Lábár, János
ED  - Tomanek, P
ED  - Kolarik, R
TI  - "ProcessDiffraction": A computer program to process electron diffraction patterns from polycrystalline or amorphous samples
T2  - Proceedings of the 12th European Congress on Electron Microscopy
C1  - Brno
PY  - 2000
SP  - I 379
EP  - I 380
UR  - https://m2.mtmt.hu/api/publication/1169478
ID  - 1169478
LA  - English
DB  - MTMT
ER  -