Quantitative Analyses of Precession Diffraction Data for a Large Cell Oxide

2004 ◽  
Vol 10 (1) ◽  
pp. 96-104 ◽  
Author(s):  
Christopher S. Own ◽  
Arun K. Subramanian ◽  
Laurence D. Marks
Keyword(s):  
Electron Diffraction ◽  
Diffraction Data ◽  
Large Cell ◽  
Unit Cell ◽  
Large Unit ◽  
Structure Solution ◽  
Precession Electron Diffraction ◽  
Quantitative Analyses ◽  
Large Unit Cell

Kinematical and two-beam calculations have been conducted and are compared to experimental precession data for the large unit cell crystal La4Cu3MoO12. Precession electron diffraction intensities are found to exhibit approximate two-beam behavior and demonstrate clear advantages over conventional SADP intensities for use in structure solution.

ELECTRON DIFFRACTION AND PHOTOEMISSION STUDIES OF CLEAN AND WATER-COVERED Si(5,5,12) AND Si(112) SURFACES

1997 ◽  
Vol 04 (01) ◽  
pp. 15-23 ◽  
Author(s):  
W. RANKE ◽  
Y. R. XING
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Unit Cell ◽  
Silicon Surfaces ◽  
Structure Model ◽  
Large Unit ◽  
Stable Orientation ◽  
Large Unit Cell

The structure of silicon surfaces in the orientation range (113)–(5,5,12)–(337)–(112) has been investigated using high resolution LEED and photoemission both on a spherical and on flat samples. We find that Si(5,5,12) [5.3° from (113) and 0.7° from (337)] is the only stable orientation between (113) and (111) and confirm the result of Baski et al. [Science269, 1556 (1995)] that it has a 2 × 1 superstructure with a very large unit cell of 7.68 × 53.5 Å2. Adsorption measurements of water on Si(5,5,12) yield a mobile precursor kinetics with two kinds of regions saturating at 0.25 and 0.15 ML which are related to adsorption on different sites. Using these results, a modified structure model is proposed. Surfaces between (113) and (5,5,12) separate into facets of these two orientations; between (5,5,12) and (112), they separate into (5,5,12) and (111) facets. (337) facets in this range may be considered as defective (5,5,12) facets.

Direct space structure solution from precession electron diffraction data: Resolving heavy and light scatterers in Pb13Mn9O25

2010 ◽  
Vol 110 (7) ◽  
pp. 881-890 ◽  
Author(s):  
Joke Hadermann ◽  
Artem M. Abakumov ◽  
Alexander A. Tsirlin ◽  
Vladimir P. Filonenko ◽  
Julie Gonnissen ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Diffraction Data ◽  
Space Structure ◽  
Electron Diffraction Data ◽  
Structure Solution ◽  
Precession Electron Diffraction

scholarly journals Combining precession electron diffraction data with X-ray powder diffraction data to facilitate structure solution

2008 ◽  
Vol 41 (6) ◽  
pp. 1115-1121 ◽  
Author(s):  
Dan Xie ◽  
Christian Baerlocher ◽  
Lynne B. McCusker
Keyword(s):  
Electron Diffraction ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Electron Diffraction Data ◽  
Powder Diffraction Data ◽  
Powder Charge ◽  
X Ray ◽  
Structure Solution ◽  
Precession Electron Diffraction ◽  
Using Data

Information derived from precession electron diffraction (PED) patterns can be used to advantage in combination with high-resolution X-ray powder diffraction data to solve crystal structures that resist solution from X-ray data alone. PED data have been exploited in two different ways for this purpose: (1) to identify weak reflections and (2) to estimate the phases of the reflections in the projection. The former is used to improve the partitioning of the reflection intensities within an overlap group and the latter to provide some starting phases for structure determination. The information was incorporated into a powder charge-flipping algorithm for structure solution. The approaches were first developed using data for the moderately complex zeolite ZSM-5, and then tested on TNU-9, one of the two most complex zeolites known. In both cases, including PED data from just a few projections facilitated structure solution significantly.

scholarly journals A complicated quasicrystal approximant ∊16 predicted by the strong-reflections approach

2010 ◽  
Vol 66 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Mingrun Li ◽  
Junliang Sun ◽  
Peter Oleynikov ◽  
Sven Hovmöller ◽  
Xiaodong Zou ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Unit Cell ◽  
Space Groups ◽  
Inverse Fourier Transformation ◽  
Transmission Electron ◽  
Structure Factors ◽  
Precession Electron Diffraction ◽  
Density Map ◽  
Electron Density Map ◽  
Good Agreement

The structure of a complicated quasicrystal approximant ∊16 was predicted from a known and related quasicrystal approximant ∊6 by the strong-reflections approach. Electron-diffraction studies show that in reciprocal space, the positions of the strongest reflections and their intensity distributions are similar for both approximants. By applying the strong-reflections approach, the structure factors of ∊16 were deduced from those of the known ∊6 structure. Owing to the different space groups of the two structures, a shift of the phase origin had to be applied in order to obtain the phases of ∊16. An electron-density map of ∊16 was calculated by inverse Fourier transformation of the structure factors of the 256 strongest reflections. Similar to that of ∊6, the predicted structure of ∊16 contains eight layers in each unit cell, stacked along the b axis. Along the b axis, ∊16 is built by banana-shaped tiles and pentagonal tiles; this structure is confirmed by high-resolution transmission electron microscopy (HRTEM). The simulated precession electron-diffraction (PED) patterns from the structure model are in good agreement with the experimental ones. ∊16 with 153 unique atoms in the unit cell is the most complicated approximant structure ever solved or predicted.

scholarly journals Towards Routine Structure Solution using Precession Electron Diffraction

2009 ◽  
Vol 15 (S2) ◽  
pp. 738-739
Author(s):  
PA Midgley ◽  
A Eggeman ◽  
T White ◽  
E Bithell
Keyword(s):  
Electron Diffraction ◽  
Structure Solution ◽  
Precession Electron Diffraction

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

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