scholarly journals Advanced analysis of neutron total scattering data: modelling disorder in network structures

2004 ◽  
Vol 60 (a1) ◽  
pp. s104-s104
Author(s):  
D. A. Keen ◽  
M. T. Dove ◽  
M. G. Tucker
Keyword(s):  
Scattering Data ◽  
Network Structures ◽  
Data Modelling ◽  
Total Scattering ◽  
Advanced Analysis ◽  
Neutron Total Scattering

scholarly journals The atomic structure of a MgCo2O4 nanoparticle for a positive electrode of a Mg rechargeable battery

2019 ◽  
Vol 55 (17) ◽  
pp. 2517-2520 ◽  
Author(s):  
Naoto Kitamura ◽  
Yuhei Tanabe ◽  
Naoya Ishida ◽  
Yasushi Idemoto
Keyword(s):  
Monte Carlo ◽  
Atomic Structure ◽  
Positive Electrode ◽  
Scattering Data ◽  
Rechargeable Battery ◽  
Reverse Monte Carlo ◽  
Spinel Type ◽  
Total Scattering ◽  
X Ray ◽  
Neutron Total Scattering

The atomic structure of a spinel-type MgCo2O4 nanoparticle was investigated by the reverse Monte Carlo modelling using X-ray and neutron total scattering data.

MCGRtof: Monte CarloG(r) with resolution corrections for time-of-flight neutron diffractometers

2001 ◽  
Vol 34 (6) ◽  
pp. 780-782 ◽  
Author(s):  
Matthew G. Tucker ◽  
Martin T. Dove ◽  
David A. Keen
Keyword(s):  
Pair Distribution Function ◽  
Time Of Flight ◽  
Distribution Functions ◽  
Monte Carlo Algorithm ◽  
Scattering Data ◽  
Spallation Neutron Source ◽  
Total Scattering ◽  
Inverse Monte Carlo ◽  
Pair Distribution Functions ◽  
Neutron Total Scattering

A new implementation of the programMCGR[Pusztai & McGreevy (1997).Physica B,234–236, 357–358] for the calculation of pair distribution functions from neutron total scattering data using an inverse Monte Carlo algorithm is presented. The new implementation, calledMCGRtof, incorporates the resolution functions for time-of-flight neutron diffractometers, and is suitable for analysis of data from instruments such as GEM at the ISIS spallation neutron source. The effect of including resolution correctly is to increase the magnitude of the pair distribution function at larger distances. The working program is illustrated with total scattering measurements from crystalline AlPO4.

Neutron total scattering of crystalline materials in the gigapascal regime

2017 ◽  
Vol 50 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Helen Y. Playford ◽  
Matthew G. Tucker ◽  
Craig L. Bull
Keyword(s):  
High Pressure ◽  
Structural Information ◽  
Functional Materials ◽  
Planetary Science ◽  
Scattering Data ◽  
Structure Property ◽  
Total Scattering ◽  
Crystalline Materials ◽  
Time Required ◽  
Neutron Total Scattering

Neutron total scattering of disordered crystalline materials provides direct experimental access to the local (short-range) structure. The ways in which this local structure agrees (or disagrees) with the long-range crystal structure can provide important insight into structure–property relationships. High-pressure neutron diffraction using a Paris–Edinburgh (P–E) pressure cell allows experimenters to explore the ways in which materials are affected by pressure, can reveal new synthetic routes to novel functional materials and has important applications in many areas, including geology, engineering and planetary science. However, the combination of these two experimental techniques poses unique challenges for both data collection and analysis. In this paper it is shown that, with only minor modifications to the standard P–E press setup, high-quality total scattering data can be obtained from crystalline materials in the gigapascal pressure regime on the PEARL diffractometer at ISIS. The quality of the data is assessed through the calculation of coordination numbers and the use of reverse Monte Carlo refinements. The time required to collect data of sufficient quality for detailed analysis is assessed and is found to be of the order of 8 h for a quartz sample. Finally, data from the perovskite LaCo0.35Mn0.65O3 are presented and reveal that PEARL total scattering data offer the potential of extracting local structural information from complex materials at high pressure.

scholarly journals Local and long-range atomic/magnetic structure of non-stoichiometric spinel iron oxide nanocrystallites

IUCrJ ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 33-45
Author(s):  
Henrik L. Andersen ◽  
Benjamin A. Frandsen ◽  
Haraldur P. Gunnlaugsson ◽  
Mads R. V. Jørgensen ◽  
Simon J. L. Billinge ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Magnetic Nanoparticles ◽  
Iron Oxide Nanoparticles ◽  
Structural Characterization ◽  
Magnetic Domain ◽  
Scattering Data ◽  
Oxide Nanoparticles ◽  
Total Scattering ◽  
X Ray ◽  
Neutron Total Scattering

Spinel iron oxide nanoparticles of different mean sizes in the range 10–25 nm have been prepared by surfactant-free up-scalable near- and super-critical hydrothermal synthesis pathways and characterized using a wide range of advanced structural characterization methods to provide a highly detailed structural description. The atomic structure is examined by combined Rietveld analysis of synchrotron powder X-ray diffraction (PXRD) data and time-of-flight neutron powder-diffraction (NPD) data. The local atomic ordering is further analysed by pair distribution function (PDF) analysis of both X-ray and neutron total-scattering data. It is observed that a non-stoichiometric structural model based on a tetragonal γ-Fe2O3 phase with vacancy ordering in the structure (space group P43212) yields the best fit to the PXRD and total-scattering data. Detailed peak-profile analysis reveals a shorter coherence length for the superstructure, which may be attributed to the vacancy-ordered domains being smaller than the size of the crystallites and/or the presence of anti-phase boundaries, faulting or other disorder effects. The intermediate stoichiometry between that of γ-Fe2O3 and Fe3O4 is confirmed by refinement of the Fe/O stoichiometry in the scattering data and quantitative analysis of Mössbauer spectra. The structural characterization is complemented by nano/micro-structural analysis using transmission electron microscopy (TEM), elemental mapping using scanning TEM, energy-dispersive X-ray spectroscopy and the measurement of macroscopic magnetic properties using vibrating sample magnetometry. Notably, no evidence is found of a Fe3O4/γ-Fe2O3 core-shell nanostructure being present, which had previously been suggested for non-stoichiometric spinel iron oxide nanoparticles. Finally, the study is concluded using the magnetic PDF (mPDF) method to model the neutron total-scattering data and determine the local magnetic ordering and magnetic domain sizes in the iron oxide nanoparticles. The mPDF data analysis reveals ferrimagnetic collinear ordering of the spins in the structure and the magnetic domain sizes to be ∼60–70% of the total nanoparticle sizes. The present study is the first in which mPDF analysis has been applied to magnetic nanoparticles, establishing a successful precedent for future studies of magnetic nanoparticles using this technique.

A Bayesian approach to removal of incoherent scattering from neutron total-scattering data

2014 ◽  
Vol 47 (6) ◽  
pp. 2060-2068 ◽  
Author(s):  
Anton Gagin ◽  
Igor Levin
Keyword(s):  
Probability Distributions ◽  
Simulated Data ◽  
Incoherent Scattering ◽  
Scattering Data ◽  
Data Sets ◽  
Background Signal ◽  
Total Scattering ◽  
Public Domain Software ◽  
Principle Of Maximum ◽  
Neutron Total Scattering

A Bayesian statistics approach for subtraction of incoherent scattering from neutron total-scattering data has been developed and implemented in a public domain software package. In this approach, the estimated background signal associated with incoherent scattering maximizes the posterior probability, which combines the likelihood of this signal in reciprocal and real spaces with the prior that favors smooth lines. The probability distributions are constructed according to the principle of maximum entropy. The method enables robust subtraction of incoherent-scattering backgrounds while providing estimated uncertainties for recovered signals. The developed procedure was first tested using simulated data and then demonstrated using three representative experimental data sets, collected on bulk materials and nanoparticles, featuring distinct ratios of coherent to incoherent scattering.

scholarly journals Improving the accuracy of time-of-flight neutron total scattering data and analysis

2017 ◽  
Vol 73 (a1) ◽  
pp. a215-a215
Author(s):  
Daniel Olds ◽  
Richard Archibald ◽  
Thomas Proffen ◽  
Katharine Page
Keyword(s):  
Time Of Flight ◽  
Scattering Data ◽  
Total Scattering ◽  
Neutron Total Scattering
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