scholarly journals Evaluation of the Structure of Amorphous Tungsten Oxide W28O72 by the Combination of Electron-, X-Ray- and Neutron-Diffraction (Three-Beam Experiment)

2006 ◽  
Vol 61 (3-4) ◽  
pp. 189-196 ◽  
Author(s):  
Jürgen Ankele ◽  
Joachim Mayer ◽  
Peter Lamparter ◽  
Siegfried Steeb
Keyword(s):  
Neutron Diffraction ◽  
Diffraction Data ◽  
Structural Model ◽  
Pair Correlation ◽  
Electron Diffraction Data ◽  
X Ray ◽  
Structure Factors ◽  
Beam Experiment ◽  
Reverse Monte Carlo Simulation ◽  
Sputter Deposited

From the combination of quantitative electron-diffraction data with X-ray- and neutron-diffraction data (so-called three-beam experiment) the partial structure factors and pair correlation functions of amorphous sputter deposited W28O72 were determined. On the basis of the experimental atomic distances and coordination numbers, and by comparison with crystalline WO3, a structural model was developed, which consists of twisted WO6 octahedra. Reverse Monte Carlo simulation in accordance with the experimental data was performed to verify the results

Electron Diffraction with the Amorphous Alloys Fe80B20 and Mn73Si27

1982 ◽  
Vol 37 (11) ◽  
pp. 1215-1222
Author(s):  
F. Paasche ◽  
H. Olbrich ◽  
G. Rainer-Harbach ◽  
P. Lamparter ◽  
S. Steeb
Keyword(s):  
Electron Diffraction ◽  
Neutron Diffraction ◽  
Amorphous Alloys ◽  
Pair Correlation ◽  
Diffraction Experiment ◽  
Partial Structure ◽  
Neutron Diffraction Experiment ◽  
X Ray ◽  
Structure Factors ◽  
Beam Experiment

Electron diffraction with amorphous Fe80B20 and Mn73Si27 yields structure factors and pair correlation functions which are discussed together with the results of X-ray- and neutron-diffraction experiments. For Mn73Si27 additional interesting details are revealed. A tetrahedral model for Mn73Si27 is described. Finally we show that the evaluation of partial structure factors by the three beam experiment, i.e. the combination of an electron-, X-ray- and neutron-diffraction experiment is not possible in general.

scholarly journals X-Ray and Neutron Diffraction of Amorphous Nickel-Zirconium-Alloys as Prepared in Different Ways

1991 ◽  
Vol 46 (6) ◽  
pp. 491-498 ◽  
Author(s):  
L. Schultz ◽  
P. Lamparter ◽  
S. Steeb
Keyword(s):  
Neutron Diffraction ◽  
Short Range ◽  
Melt Spinning ◽  
Short Range Order ◽  
Pair Correlation ◽  
Zirconium Alloys ◽  
X Ray ◽  
Coordination Numbers ◽  
Structure Factors ◽  
The One

AbstractThe structure of amorphous NiχZr100-χ-alloys (Χ= 30, 31, 34, 63.7, and 65), which were produced by melt spinning (MS), mechanical alloying (MA), and sputtering (SP) was studied by X-ray- and neutron diffraction yielding structure factors, pair correlation functions, coordination numbers, atomic distances, and Warren-Cowley chemical short range order parameters. The atomic arrangement within the first coordination sphere is independent of the method of preparation while in the second and higher spheres it differs between the MS- and the MA-alloys on the one side and the SP-specimens on the other side. Thus one understands that some physical properties of the different specimens differ

X-ray- and Neutron-diffraction Studies with Quasicrystalline and Amorphous Al-V- and Al-Mn-alloys

1990 ◽  
Vol 45 (5) ◽  
pp. 627-638
Author(s):  
S. Seehafer ◽  
P. Lamparter ◽  
S. Steeb
Keyword(s):  
Neutron Diffraction ◽  
Coordination Number ◽  
Correlation Functions ◽  
Melt Spinning ◽  
Pair Correlation ◽  
Partial Density ◽  
Isomorphous Substitution ◽  
Hard Sphere Model ◽  
X Ray ◽  
Structure Factors

Abstract Amorphous and quasicrystalline samples of Al84Mn16 and Al84V16 were produced by sputtering and melt-spinning, respectively. From X-ray and neutron-diffraction-results the total structure factors were evaluated. For amorphous as well as for quasicrystalline Al84V16 the partial SAl-Al- and SAl-V-structure factors were obtained, which yield the corresponding partial pair correlation functions, the atomic distances, and the partial coordination numbers. Also some information concerning the partial Bhatia-Thornton correlation functions could be obtained. Both the amorphous and the quasicrystalline Al-V-alloys show a linear expansion by a factor of 1.03 compared to the corresponding Al-Mn-alloy. The two amorphous alloys can be designed as isomorphous, whereas the quasicrystalline ones show pronounced deviations in the distance between unequal atoms. The shortest atomic distance in amorphous Al84V16 is 2.69 A, being,formed by Al-V-pairs with a coordination number 2. The nearest Al-Al-distance amounts to 2.84 A with a coordination number 8. The partial density-concentration correlation function clearly deviates from the hard sphere model. With the quasicrystalline specimens, the isomorphous substitution of Mn- and V-atoms is not perfect. The Al-V-correlation is split up, and this is not observed for the Al-Mn-correlation. Comparison of the amorphous and the corresponding quasicrystalline alloy shows some similarities

scholarly journals Analysis of Sr3-xCa1+xMn2CoO9 combining electron, X-ray and neutron diffraction

2014 ◽  
Vol 70 (a1) ◽  
pp. C929-C929
Author(s):  
Philippe Boullay ◽  
Olivier Pérez ◽  
Bernard Raveau ◽  
Seikh Motin ◽  
Caignaert Vincent
Keyword(s):  
Electron Diffraction ◽  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structural Model ◽  
X Ray ◽  
Cell Parameters ◽  
Precession Electron Diffraction ◽  
Different Temperatures ◽  
Scattering Lengths

The AxBX3 hexagonal perovskite-type compounds exhibit interesting magnetic properties such as complex magnetism or random spin chain magnetism[1,2]. Their structures are built up from infinite [BO3] chains consisting of alternating octahedral and trigonal prismatic units, separated by A infinite chains. Sr3-xCa1+xMn2CoO9 are belonging to this family of materials. X-ray powder diffraction patterns are collected for different Sr3-xCa1+xMn2CoO9 samples with different x values. Pattern matching analysis with the SG P-3 and the following cell parameters a=b=9.490(1)Å c=3xc'=3x2.57=7.732(1)Å reveals problematic groups of reflections; these reflections are shifted from one pattern to another one and, moreover, have positions preventing their indexation. Owing to the lack of spatial resolution and peaks overlapping in the powder data, the understanding of the present problem is quite impossible. Electron Diffraction Tomography (EDT) combined with Precession Electron Diffraction (PED) has been used for exploring the reciprocal space of the Sr3-xCa1+xMn2CoO9, x=0 sample. The slight deviations observed from the rational 1/3 c'* value is in agreement with the existence of aperiodicities. The structure of this family of materials has been then described using the super space formalism as a composite structure. The structural model is determined from the PED data integrated with PETS[2]; the first and second sublattices are referring to (Mn,Co)O3 and (Ca,Sr) structural parts respectively. This model is confirmed by the refinement of the X-ray powder diffraction data. Powder neutron diffraction data were then collected at PSI for different temperatures and different Sr3-xCa1+xMn2CoO9 samples. Using the previously refined model, a Co/Mn ordering is revealed thanks to the neutron scattering lengths of these two elements (see fig1). Finally, the treatment of the antiferromagnetic behavior observed bellow 25K is performed in the 4d approach using Jana2006[3].

Dynamical Structure Factors for Bent Organic Crystals

1982 ◽  
Vol 40 ◽  
pp. 94-95
Author(s):  
Barbara Moss ◽  
Douglas L. Dorset
Keyword(s):  
Electron Diffraction ◽  
Diffraction Data ◽  
Electron Diffraction Data ◽  
Dynamical Structure ◽  
Organic Crystals ◽  
Beam Direction ◽  
Scattering Intensity ◽  
X Ray ◽  
Structure Factors ◽  
Long Chain

The success of quantitative crystal structure determination from electron diffraction data requires a valid analysis of the observed intensities. Traditional X-ray crystallographic techniques rely on the kinematic scattering model. However, some organic microcrystals exhibit significant dynamical scattering from extremely thin specimens and crystal bending further complicates the observed scattering intensity. While each of these data perturbations has been studied separately, a combined calculation is important to indicate the validity of separate treatments. Solution-grown hexatriacontane, C36 H74, a long-chain hydrocarbon with the long axis (c=95.14Å) parallel to the electron beam direction exhibits significant dynamical and bend effects. It is thus a particularly difficult structure to analyse from hkO electron diffraction data. Multislice dynamical calculations for a curved crystal lattice of this material are considered.

Structure of Sputtered Amorphous Zr-Hf-Si Alloys

1999 ◽  
Vol 54 (12) ◽  
pp. 699-703
Author(s):  
A. Pojtinger ◽  
P. Lamparter ◽  
S. Steeb
Keyword(s):  
Amorphous Alloys ◽  
Short Range ◽  
Pair Correlation ◽  
Isomorphous Substitution ◽  
X Ray Diffraction ◽  
Partial Functions ◽  
X Ray ◽  
Structure Factors ◽  
Reverse Monte Carlo Simulation ◽  
Total Structure

Abstract Amorphous (Zr,Hf)37Si63 alloys were produced by sputtering. Their total structure factors were determined by X-ray diffraction. Using the methods of isomorphous substitution and Reverse Monte Carlo simulation, the partial pair correlation functions were obtained. The results were compared with the partial functions of amorphous Ti40Si60. In the amorphous alloys under investigation the transition metal -metalloid correlation dominates the short range order.

Atomic Structure of Rare Earth Si-Al-O-N Glasses

1998 ◽  
Vol 53 (5) ◽  
pp. 259-264 ◽  
Author(s):  
H. Uhlig ◽  
M.-J. Hoffmann ◽  
S. Steeb
Keyword(s):  
Rare Earth ◽  
Neutron Diffraction ◽  
Atomic Structure ◽  
Pair Correlation ◽  
X Ray Diffraction ◽  
Ionic Radii ◽  
X Ray ◽  
Structure Factors ◽  
Total Structure

Abstract In this paper the results of X-ray diffraction experiments of Ln-Si-Al-O-N (Ln = La, Gd, Yb) glasses are presented. Total structure factors and pair correlation functions allow the determination of the first coordination sphere of Ln atoms. The bond lengths observed correspond to the ionic radii of the Ln-ions surrounded by oxygen and nitrogen atoms. The presence of non-bridging nitrogen is discussed together with results of neutron diffraction, NMR-experiments and XPS-studies of other authors.

Daliranite, PbHgAs2S5: determination of the incommensurately modulated structure and revision of the chemical formula

2019 ◽  
Vol 75 (4) ◽  
pp. 711-716 ◽  
Author(s):  
Arianna E. Lanza ◽  
Mauro Gemmi ◽  
Luca Bindi ◽  
Enrico Mugnaioli ◽  
Werner H. Paar
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Structural Model ◽  
Electron Diffraction Data ◽  
Chemical Formula ◽  
Modulated Structure ◽  
X Ray

The incommensurately modulated crystal structure of the mineral daliranite has been determined using 3D electron diffraction data obtained on nanocrystalline domains. Daliranite is orthorhombic with a = 21, b = 4.3, c = 9.5 Å and shows modulation satellites along c. The solution of the average structure in the Pnma space group together with energy-dispersive X-ray spectroscopy data obtained on the same domains indicate a chemical formula of PbHgAs2S5, which has one S fewer than previously reported. The crystal structure of daliranite is built from columns of face-sharing PbS8 bicapped trigonal prisms laterally connected by [2+4]Hg polyhedra and (As3+ 2S5)4− groups. The excellent quality of the electron diffraction data allows a structural model to be built for the modulated structure in superspace, which shows that the modulation is due to an alternated occupancy of a split As site.

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