Direct Measurement of the Hydrogen-Hydrogen Correlations in Hydrogenated Amorphous Ni56 Dy44 by Neutron Diffraction

1998 ◽  
Vol 53 (9) ◽  
pp. 766-770
Author(s):  
P. Lamparter ◽  
Ma. Nuding ◽  
S. Steeb ◽  
R. Bellissent
Keyword(s):  
Neutron Diffraction ◽  
Neutron Scattering ◽  
Melt Spinning ◽  
Scattering Length ◽  
Pair Correlation ◽  
Main Peak ◽  
Neutron Diffraction Experiment ◽  
Isotopic Mixture ◽  
Nearest Neighbours ◽  
Hydrogenated Amorphous

Abstract From an isotopic mixture of dysprosium with zero neutron scattering length and an isotopic mixture of nickel with zero neutron scattering length ribbons of the amorphous alloy Ni56 Dy44 were produced by melt-spinning and loaded with 59 at% deuterium. A neutron diffraction experiment yielded directly the deuterium-deuterium partial structure factor SDD and the partial pair correlation function GDD . The incorporation of the D-atoms into the amorphous matrix shows an ordering up to five coordination shells at least. The main peak of GDD is split up into a contribution at 2.36 Å with 5.4 nearest neighbours and a contribution at 2.76 Å with 4 neighbours. The D-atoms are located preferentially in Dy4 -tetrahedra, where the occupation of two neighbouring face-sharing tetrahedra is avoided.

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

Evidence of bayerite clusters within the AAO amorphous bulk alumina. Consequence for AAO SANS matching properties.

2008 ◽  
Vol 1074 ◽  
Author(s):  
Karine Lagrené ◽  
Jean-Marc Zanotti
Keyword(s):  
Neutron Diffraction ◽  
Neutron Scattering ◽  
Porous Structure ◽  
Small Angle ◽  
Large Scale ◽  
Scattering Length ◽  
Synthesis Process ◽  
Important Input ◽  
Contrast Matching ◽  
Anodic Synthesis

ABSTRACTSmall Angle Neutron Scattering (SANS) and neutron diffraction are used to probe the structure of Anodized Aluminium Oxide (AAO) in an extended Q range, from 7.10−3 to 16 Å−1. In the small angle region [7. 10−3 Å−1 − 7. 10−2 Å−1], impregnation of a D2O/H2O mixture within the AAO porous structure, leads to a dramatic decrease of the coherent SANS signal by two orders of magnitude, but perfect matching of the membrane cannot be reached. We explain such an imperfect matching by the presence of 1 nm in size Bayerite domains within the bulk of the amorphous Al2O3 matrix, as detected by Neutron diffraction in the [0.3 Å−1 − 4 Å−1] Q range. Traces of sulfur, probably incorporated during the anodic synthesis process in a H2SO4 solution, are also detected by Scanning Electron Microscopy with Energy Dispersive X-ray analysis (SEM-EDX). We estimate the AAO neutron scattering length to be 4.22 1010 cm−2. This value is an important input, when taking advantage of neutron contrast matching to probe the large scale filling homogeneity (adsorption of a liquid or deposition of a solid) within the porous structure of AAO membranes.

Neutron Diffraction Study on the Structure of Liquid Cs-Sb Alloys

1983 ◽  
Vol 38 (3) ◽  
pp. 329-335 ◽  
Author(s):  
P. Lamparter ◽  
W. Martin ◽  
S. Steeb ◽  
W. Freyland
Keyword(s):  
Neutron Diffraction ◽  
Pair Correlation ◽  
Neutron Diffraction Study ◽  
Main Peak ◽  
Continuous Change ◽  
Structure Factors ◽  
Angle Scattering ◽  
Solid Compounds ◽  
Total Structure ◽  
The Stability

Abstract By neutron diffraction experiments the total structure factors and the total pair correlation functions of liquid Cs-Sb alloys containing 85, 75, 65, and 50 at% Cs, respectively, were determined. The structural results confirm the non metallic properties of Cs-Sb melts.The correspondence of the nearest neighbour atomic arrangement in liquid Cs75Sb25 and in the solid compound semiconductor Cs3Sb suggests a similar type of bonding, namely by valence bonds and ionic forces simultaneously. The stability of this compound in the molten state leads to a microsegregation tendency between compound forming regions and excess Cs in the concentration range from pure Cs up to 25 at% Sb, which is established by a small angle scattering effect.Proceeding from Cs75Sb25 to Cs50Sb50, a continuous change in the structure takes place. Covalently bonded Sb chains are formed just as found in the corresponding solid compounds ASb (A = alkali metal). An additional diffraction peak in front of the main peak of the structure factors within this composition range implies the formation of rather large molecular clusters in the alloys.

The crystal structure of tricaesium tetrabromocobaltate(II) bromide, Cs3CoBr5, at 4.2 K by neutron diffraction

1981 ◽  
Vol 34 (12) ◽  
pp. 2495 ◽  
Author(s):  
BN Figgis ◽  
PA Reynolds
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Neutron Scattering ◽  
Single Crystal ◽  
Bond Length ◽  
Least Squares ◽  
Metal Ion ◽  
Scattering Length ◽  
Scattering Lengths ◽  
The Stability

The crystal structure of Cs3CoBr5 [I4/mcm, a 946(1), c 1504(2) pm, U 1.346(7) nm3, Z 4] has been determined at 4.2 K by single-crystal neutron diffraction methods. The Co-Br bond length is 239.8(2) pm, and the Br-Co-Br angles of the distorted tetrahedral cobalt environment are 107.58(9) and 110.43(9)�. The neutron scattering lengths of cobalt and bromine were found, by least-squares refinement, to be 2.46(2) × 10-15 and 6.78(2) × 10-15 m respectively, relative to a caesium scattering length of 5.38 × 10-l5 m. The contact distances and thermal parameters of Cs3CoBr5, when compared with those from Cs3CoCl5, provide further evidence on the stability of M3CoX5 salts. The metal ion must be sufficiently large to adequately fill the large holes in the lattice whose size is determined by X-...X- contacts.

Investigation of Mg-Bi Melts by Means of X-Ray- and Neutron Diffraction

1979 ◽  
Vol 34 (12) ◽  
pp. 1398-1403 ◽  
Author(s):  
Michael Weber ◽  
Siegfried Steeb ◽  
Peter Lamparter
Keyword(s):  
Neutron Diffraction ◽  
Pair Correlation ◽  
Distribution Functions ◽  
Nearest Neighbour ◽  
X Ray Diffraction ◽  
Neighbour Distance ◽  
X Ray ◽  
Structure Factors ◽  
Nearest Neighbours ◽  
Total Structure

Abstract Neutron diffraction experiments were done on Mg-Bi melts with eight compositions. From the measured intensities total structure factors and pair correlation functions as well as radial atomic distribution functions were calculated. The concentration dependence of the measured nearest neighbour distance and measured coordination number indicates the preference of unlike nearest neighbours within the Mg-Bi melts.The neutron-intensity curves show premaxima at q ≅ 1.6 Å-1. X-Ray diffraction experiments performed on melts with three different compositions also yield corresponding premaxima. It could be shown that the premaximum intensity from the X-Ray as well as from the neutron experiment corresponds to the assumption that the premaxima are caused by modulation of the monotonic Laue scattering.

Neutron scattering length determination by means of total scattering

2018 ◽  
Vol 51 (3) ◽  
pp. 854-866 ◽  
Author(s):  
Alex C. Hannon ◽  
Alexandra S. Gibbs ◽  
Hidenori Takagi
Keyword(s):  
Correlation Function ◽  
Neutron Diffraction ◽  
Neutron Scattering ◽  
Cross Sections ◽  
Scattering Length ◽  
Neutron Diffraction Pattern ◽  
Average Density ◽  
A Value ◽  
Oxide Crystal ◽  
Scattering Lengths

A new method for the measurement of bound coherent neutron scattering lengths is reported. It is shown that a relative measurement of the neutron scattering length, {\overline b}, of an element can be made by analysis of the neutron correlation function of a suitable oxide crystal powder. For this analysis, it is essential to take into account the average density contribution to the correlation function, as well as the contributions arising from distances between atoms in the crystal. The method is demonstrated and verified by analysis of the neutron correlation function for the corundum form of Al2O3, yielding a value {\overline b} = 3.44 (1) fm for Al, in good agreement with the literature. The method is then applied to the isotopes of iridium, for which the values of the scattering lengths were unknown, and which are difficult to investigate by other methods owing to the large cross sections for the absorption of neutrons. The neutron correlation function of a sample of Sr2IrO4 enriched in 193Ir is used to determine values {\overline b} = 9.71 (18) fm and {\overline b} = 12.1 (9) fm for 193Ir and 191Ir, respectively, and these are consistent with the tabulated scattering length and cross sections of natural Ir. These values are of potential application for obtaining improved neutron diffraction results on iridates by the use of samples enriched in 193Ir, so that the severe absorption problems associated with 191Ir are avoided. Rietveld refinement of the neutron diffraction pattern of isotopically enriched Sr2IrO4 is used to yield a similar result for Ir. However, in practice the Rietveld result is shown to be less reliable because of correlation between the parameters of the fit.

Real-space interpretation of spin-echo small-angle neutron scattering

2003 ◽  
Vol 36 (1) ◽  
pp. 117-124 ◽  
Author(s):  
Timofei Krouglov ◽  
Ignatz M. de Schepper ◽  
Wim G. Bouwman ◽  
M. Theo Rekveldt
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Spin Echo ◽  
Scattering Length ◽  
Structural Parameters ◽  
Pair Correlation ◽  
Real Space ◽  
Radius Of Gyration ◽  
Solid Spheres

Spin-echo small-angle neutron scattering (SESANS) is a novel real-space scattering technique. SESANS measures a correlation-like functionG(Z), the meaning of which was unknown until now. Here a direct real-space interpretation ofG(Z) through the particle scattering density and pair correlation function is given. One-dimensional and two-dimensional SESANS are compared. The case of non-interacting particles is considered in detail with an explicit geometrical interpretation. General methods for the calculation of structural parameters, such as the total scattering length and the radius of gyration, are developed. Analytical expressions ofG(Z) for non-interacting solid spheres, hollow spheres and Gaussian coils are derived. The case of solid spheres is compared with experimental data.

scholarly journals Neutron sub-micrometre tomography from scattering data

IUCrJ ◽  
2020 ◽  
Vol 7 (5) ◽  
pp. 893-900
Author(s):  
B. Heacock ◽  
D. Sarenac ◽  
D. G. Cory ◽  
M. G. Huber ◽  
J. P. W. MacLean ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Neutron Scattering ◽  
Spatial Resolution ◽  
Phase Retrieval ◽  
Scattering Length ◽  
Neutron Imaging ◽  
Scattering Data ◽  
Retrieval Algorithm ◽  
Scanning Electron Micrographs ◽  
Topological Features

Neutrons are valuable probes for various material samples across many areas of research. Neutron imaging typically has a spatial resolution of larger than 20 µm, whereas neutron scattering is sensitive to smaller features but does not provide a real-space image of the sample. A computed-tomography technique is demonstrated that uses neutron-scattering data to generate an image of a periodic sample with a spatial resolution of ∼300 nm. The achieved resolution is over an order of magnitude smaller than the resolution of other forms of neutron tomography. This method consists of measuring neutron diffraction using a double-crystal diffractometer as a function of sample rotation and then using a phase-retrieval algorithm followed by tomographic reconstruction to generate a map of the sample's scattering-length density. Topological features found in the reconstructions are confirmed with scanning electron micrographs. This technique should be applicable to any sample that generates clear neutron-diffraction patterns, including nanofabricated samples, biological membranes and magnetic materials, such as skyrmion lattices.

Sign in / Sign up

Export Citation Format

Share Document