scholarly journals A real-space approach to the analysis of stacking faults in close-packed metals: G(r) modelling and Q-space feedback

2020 ◽  
Vol 76 (1) ◽  
pp. 84-91
Author(s):  
Alessandro Longo ◽  
Francesco Giannici ◽  
Luisa Sciortino ◽  
Antonino Martorana
Keyword(s):  
Pair Distribution Function ◽  
Structural Model ◽  
Function Analysis ◽  
Stacking Faults ◽  
Structural Disorder ◽  
Real Space ◽  
High Angle ◽  
Debye Function ◽  
Experimental Pair ◽  
Space Approach

An R-space approach to the simulation and fitting of a structural model to the experimental pair distribution function is described, to investigate the structural disorder (distance distribution and stacking faults) in close-packed metals. This is carried out by transferring the Debye function analysis into R space and simulating the low-angle and high-angle truncation for the evaluation of the relevant Fourier transform. The strengths and weaknesses of the R-space approach with respect to the usual Q-space approach are discussed.

Real-Space X-Ray Pair Distribution Function Analysis and Molecular-Dynamics Modelling of Diflunisal Channel Hydrates

2020 ◽  
Author(s):  
Anuradha Pallipurath ◽  
Francesco Civati ◽  
Jonathan Skelton ◽  
Dean Keeble ◽  
Clare Crowley ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Distribution Function ◽  
Structural Dynamics ◽  
First Principles ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
Real Space ◽  
X Ray ◽  
Dynamics Modelling ◽  
Dynamics Simulations

X-ray pair distribution function analysis is used with first-principles molecular dynamics simulations to study the co-operative H<sub>2</sub>O binding, structural dynamics and host-guest interactions in the channel hydrate of diflunisal.

scholarly journals There's no place like real-space: elucidating size-dependent atomic structure of nanomaterials using pair distribution function analysis

2020 ◽  
Vol 2 (6) ◽  
pp. 2234-2254 ◽  
Author(s):  
Troels Lindahl Christiansen ◽  
Susan R. Cooper ◽  
Kirsten M. Ø. Jensen
Keyword(s):  
Distribution Function ◽  
Atomic Structure ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
Real Space ◽  
Size Dependent ◽  
Structure Of Nanomaterials

We review the use of pair distribution function analysis for characterization of atomic structure in nanomaterials.

Structure of nanocrystalline MgFe2O4from X-ray diffraction, Rietveld and atomic pair distribution function analysis

2005 ◽  
Vol 38 (5) ◽  
pp. 772-779 ◽  
Author(s):  
Milen Gateshki ◽  
Valeri Petkov ◽  
Swapan K. Pradhan ◽  
Tom Vogt
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Structural Information ◽  
Function Analysis ◽  
Three Dimensional ◽  
Structural Disorder ◽  
Dimensional Structure ◽  
Spinel Type ◽  
Atomic Pair Distribution Function ◽  
Atomic Pair

The three-dimensional structure of nanocrystalline magnesium ferrite, MgFe2O4, prepared by ball milling, has been determined using synchrotron radiation powder diffraction and employing both Rietveld and atomic pair distribution function (PDF) analysis. The nanocrystalline ferrite exhibits a very limited structural coherence length and a high degree of structural disorder. Nevertheless, the nanoferrite possesses a very well defined local atomic ordering that may be described in terms of a spinel-type structure with Mg2+and Fe3+ions almost randomly distributed over its tetrahedral and octahedral sites. The new structural information helps explain the material's unusual magnetic properties.

scholarly journals The Polymorphs of the Na+ Ion Conductor Na3PS4 from the Perspective of Variable Temperature Diffraction and Spectroscopy

2021 ◽  
Author(s):  
Theodosios Famprikis ◽  
Houssny Bouyanfif ◽  
Pieremanuele Canepa ◽  
James Dawson ◽  
Mohamed Zbiri ◽  
...  
Keyword(s):  
Phase Transition ◽  
Distribution Function ◽  
Order Phase Transition ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
Variable Temperature ◽  
Real Space ◽  
Bragg Diffraction ◽  
Effect Of Temperature ◽  
Ion Conductor

Solid electrolytes are crucial for next generation solid state batteries and Na<sub>3</sub>PS<sub>4</sub> is one of the most promising Na<sup>+</sup> conductors for such applications. In this contribution, we present a detailed investigation of the evolution in structure and dynamics of Na<sub>3</sub>PS<sub>4</sub> under the effect of temperature in the range 30 < T < 600 °C through combined experimental-computational analysis. Although x ray Bragg diffraction experiments indicate a second order phase transition from the tetragonal ground state (α, P-42<sub>1</sub>c) to the cubic polymorph (β, I-43m), pair distribution function analysis in real space and Raman spectroscopy indicate remnants of tetragonal character in the range 250 < T < 500 °C which we attribute to dynamic local tetragonal distortions. The first order phase transition to the mesophasic high temperature polymorph (γ, Fddd) is associated with a sharp volume increase and the onset of liquid like diffusive dynamics for sodium-cations (translative) and thiophosphate-polyanions (rotational) evident by inelastic neutron- and Raman- spectroscopies, as well as pair-distribution function and molecular dynamics. These results shed light on the rich polymorphism in Na<sub>3</sub>PS<sub>4</sub> and are relevant for a host of high performance materials deriving from the Na<sub>3</sub>PS<sub>4</sub> structural archetype.<br>

Real-Space X-Ray Pair Distribution Function Analysis and Molecular-Dynamics Modelling of Diflunisal Channel Hydrates

2020 ◽  
Author(s):  
Anuradha Pallipurath ◽  
Francesco Civati ◽  
Jonathan Skelton ◽  
Dean Keeble ◽  
Clare Crowley ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Distribution Function ◽  
Structural Dynamics ◽  
First Principles ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
Real Space ◽  
X Ray ◽  
Dynamics Modelling ◽  
Dynamics Simulations

X-ray pair distribution function analysis is used with first-principles molecular dynamics simulations to study the co-operative H<sub>2</sub>O binding, structural dynamics and host-guest interactions in the channel hydrate of diflunisal.

scholarly journals The Polymorphs of the Na+ Ion Conductor Na3PS4 from the Perspective of Variable Temperature Diffraction and Spectroscopy

2021 ◽  
Author(s):  
Theodosios Famprikis ◽  
Houssny Bouyanfif ◽  
Pieremanuele Canepa ◽  
James Dawson ◽  
Mohamed Zbiri ◽  
...  
Keyword(s):  
Phase Transition ◽  
Distribution Function ◽  
Order Phase Transition ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
Variable Temperature ◽  
Real Space ◽  
Bragg Diffraction ◽  
Effect Of Temperature ◽  
Ion Conductor

Solid electrolytes are crucial for next generation solid state batteries and Na<sub>3</sub>PS<sub>4</sub> is one of the most promising Na<sup>+</sup> conductors for such applications. In this contribution, we present a detailed investigation of the evolution in structure and dynamics of Na<sub>3</sub>PS<sub>4</sub> under the effect of temperature in the range 30 < T < 600 °C through combined experimental-computational analysis. Although x ray Bragg diffraction experiments indicate a second order phase transition from the tetragonal ground state (α, P-42<sub>1</sub>c) to the cubic polymorph (β, I-43m), pair distribution function analysis in real space and Raman spectroscopy indicate remnants of tetragonal character in the range 250 < T < 500 °C which we attribute to dynamic local tetragonal distortions. The first order phase transition to the mesophasic high temperature polymorph (γ, Fddd) is associated with a sharp volume increase and the onset of liquid like diffusive dynamics for sodium-cations (translative) and thiophosphate-polyanions (rotational) evident by inelastic neutron- and Raman- spectroscopies, as well as pair-distribution function and molecular dynamics. These results shed light on the rich polymorphism in Na<sub>3</sub>PS<sub>4</sub> and are relevant for a host of high performance materials deriving from the Na<sub>3</sub>PS<sub>4</sub> structural archetype.<br>

Analysis and modelling of structural disorder by the use of the three-dimensional pair distribution function method exemplified by the disordered twofold superstructure of decagonal Al–Cu–Co

2010 ◽  
Vol 44 (1) ◽  
pp. 134-149 ◽  
Author(s):  
Philippe Schaub ◽  
Thomas Weber ◽  
Walter Steurer
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Periodic Structures ◽  
Function Analysis ◽  
Three Dimensional ◽  
Structural Disorder ◽  
Structural Features ◽  
Direct Access ◽  
Maximum Diameter ◽  
Theoretical Concepts

Theoretical concepts and the practical application of the three-dimensional pair distribution function (3D-PDF) method and its variant, the three-dimensional Δ-pair distribution function (3D-ΔPDF) method, are presented. In analogy to traditional Patterson function analysis, advantage is taken of the Fourier transformation either of the full three-dimensional diffraction pattern of a disordered crystal or just of the isolated diffuse scattering, respectively. By the use of three-dimensional information, analysis of disorder becomes straightforward, and it becomes possible to investigate far more complicated structures than is feasible with well established powder diffraction-based PDF analysis. Compared to more traditional modelling techniques, such as Monte Carlo simulation, the 3D-ΔPDF provides direct access to disorder models and allows selective modelling of distinct structural features, which are, in contrast to reciprocal space, well localized in PDF space. The principles of the 3D-ΔPDF approach are exemplified using an analysis of the twofold (∼8 Å) periodic superstructure of a decagonal Al65Cu20Co15quasicrystal. Although analysis of disorder in quasicrystals is far more demanding than in the case of periodic structures, details of the disordered structure could be elucidated. The superstructure is found to be built from columnar units, having a maximum diameter of ∼14.5 Å. The lateral correlation between these columns is weak. Internally, the columns consist of a long-range-ordered alternation of flat and puckered layers. The development of the model and the atomic structure of the columns are described in detail.

Magnetic pair distribution function analysis: introduction and applications

2014 ◽  
Vol 70 (a1) ◽  
pp. C1459-C1459
Author(s):  
Benjamin Frandsen ◽  
Xiaohao Yang ◽  
Simon Billinge
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Short Range ◽  
Magnetic Order ◽  
Function Analysis ◽  
Real Space ◽  
Magnetic Scattering ◽  
Magnetic Correlations ◽  
Range Magnetic Order ◽  
Magnetic Pair

Short-range magnetic correlations play a crucial role in a variety of condensed matter phenomena, yet they remain notoriously difficult to investigate experimentally. Quantitative analysis of the diffuse scattering of neutrons from local magnetic correlations represents a viable but challenging route toward revealing short-range magnetic order in complex materials. Reverse Monte Carlo techniques that iteratively fit randomly generated structural models in momentum space have been used successfully [1], demonstrating that diffuse magnetic scattering can be rich in information. Recently [2], we developed a real-space approach to investigating local magnetic correlations, which we call magnetic pair distribution function (mPDF) analysis in analogy to the more familiar atomic pair distribution function. This experimentally accessible quantity reveals magnetic correlations directly in real space and places diffuse and Bragg scattering on equal footing, thereby gaining sensitivity to both short- and long-range magnetic order. Here we present the basic theory behind mPDF analysis and provide several examples of its utility using both simulated and experimentally measured data on several interesting magnetic systems, including a canonical antiferromagnetic, a spin glass, and a spin ice. We discuss the potential impact that mPDF methods may have on current and future research interests in magnetism.

Mitigation of errors in pair distribution function analysis of nanoparticles

2011 ◽  
Vol 44 (4) ◽  
pp. 788-797 ◽  
Author(s):  
Katharine Mullen ◽  
Igor Levin
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
Structural Parameters ◽  
Real Space ◽  
Scattering Data ◽  
Parameter Estimates ◽  
Total Scattering ◽  
Counting Statistics ◽  
Space Data

Information on the size and structure of nanoparticles can be obtainedviaanalysis of the atomic pair distribution function (PDF), which is calculated as the Fourier transform of X-ray/neutron total scattering. The structural parameters are commonly extracted by fitting a model PDF calculated from atomic coordinates to the experimental data. This paper discusses procedures for minimizing systematic errors in PDF calculations for nanoparticles and also considers the effects of noise due to counting statistics in total scattering data used to obtain the PDF. The results presented here demonstrate that smoothing of statistical noise in reciprocal-space data can improve the precision of parameter estimates obtained from PDF analysis, facilitating identification of the correct model (from multiple plausible choices) from real-space PDF fits.

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