Total scattering and pair distribution function analysis in modelling disorder in PZN (PbZn1/3Nb2/3O3)

Whitfield, Ross; Goossens, Darren; Welberry, T. R.

doi:10.1107/s2052252515018722

Cited by 14 publications

(13 citation statements)

References 32 publications

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“…Modern synchrotron radiation sources have led to an increasing number of cases in which diffraction and scattering can reach atomic resolution measurement (Codling et al, 2013;Keen & Goodwin, 2015). At the atomic resolution, the structure models can include the atomic anisotropic displacement parameters (ADPs) for individual atoms (Merritt, 1999;Whitfield et al, 2016). The ADPs represent atomic motions and static displacement disorder of the crystal structure, which is important to understand the physical behavior of crystals (Trueblood et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

“…Diffuse scattering influences the shape and broadness of PDF peaks (Proffen et al, 2005;Egami & Billinge, 2003;Masadeh, 2016). Whitfield et al (2016) reported that the PDF method appears to be sensitive to the ADPs and is clearly more quantitative than single-crystal diffuse scattering when refining the magnitudes of ADPs. Therefore, the PDF refinement has great potential to provide high quality ADPs for a crystal structure.…”

Section: Introductionmentioning

confidence: 99%

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Using powder XRD and pair distribution function to determine anisotropic atomic displacement parameters of orthorhombic tridymite and tetragonal cristobalite

Lee

2019

Acta Crystallogr Sect B

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Determination of the crystal structures of low-temperature tridymite and cristobalite using single-crystal XRD has been challenging because they generally occur as metastable fine-grained crystals in the geological environment. Therefore, using powder diffraction and scattering techniques is critical to study the low-temperature crystals. Synchrotron powder X-ray diffraction (XRD), pair distribution function (PDF) and transmission electron microscopy were used to investigate the structure of orthorhombic tridymite with C222 1 symmetry and tetragonal cristobalite with P4 1 2 1 2 symmetry, including their anisotropic atomic displacement parameters (ADPs). Rietveld refinement was used to determine the unit-cell parameters, fractional coordinates and isotropic atomic displacement parameters (U iso ) of the tridymite and cristobalite. The PDF method was used to determine ADPs for each atom. The results suggest that the crystal structure with high quality ADP values can be obtained using the combined methods of XRD and PDF analyses. The method can be used for characterizing crystals that are not suitable for single-crystal XRD.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Using powder XRD and pair distribution function to determine anisotropic atomic displacement parameters of orthorhombic tridymite and tetragonal cristobalite

Lee

2019

Acta Crystallogr Sect B

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“…This allows elucidation of SRO that is anisotropic or only affects small regions of reciprocal space. Similarly, the use of pair distribution function and powder diffraction is not discussed, though both are very important techniques [3,18,19,32].…”

Section: Data Collectionmentioning

confidence: 99%

“…When contrast between scatterers is weak (atoms nearby on the periodic table will have very similar X-ray scattering factors), it may be necessary to use neutron and/or X-ray single-crystal diffuse scattering (SCDS) data. Neutron diffraction requires larger crystals, which may be difficult to obtain, so it may be that X-ray SCDS is coupled with neutron pair distribution function analysis (PDF; [18][19][20]), obtained from polycrystalline specimens.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo Modelling of Single-Crystal Diffuse Scattering from Intermetallics

Goossens

2016

Metals

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Single-crystal diffuse scattering (SCDS) reveals detailed structural insights into materials. In particular, it is sensitive to two-body correlations, whereas traditional Bragg peak-based methods are sensitive to single-body correlations. This means that diffuse scattering is sensitive to ordering that persists for just a few unit cells: nanoscale order, sometimes referred to as "local structure", which is often crucial for understanding a material and its function. Metals and alloys were early candidates for SCDS studies because of the availability of large single crystals. While great progress has been made in areas like ab initio modelling and molecular dynamics, a place remains for Monte Carlo modelling of model crystals because of its ability to model very large systems; important when correlations are relatively long (though still finite) in range. This paper briefly outlines, and gives examples of, some Monte Carlo methods appropriate for the modelling of SCDS from metallic compounds, and considers data collection as well as analysis. Even if the interest in the material is driven primarily by magnetism or transport behaviour, an understanding of the local structure can underpin such studies and give an indication of nanoscale inhomogeneity.

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“…Several articles describe the role of PDF analyses in structural studies of disordered materials. Whitfield et al (2016) examine the perennially important topic of cation displacements in perovskite structured ferroelectrics, focusing on the widely studied PZN [(Pb/Zn)NbO 3 ]. They show how PDF data from powders yield valuable information on lead cation displacements, while at the same time finding that such analyses could not distinguish some of the features that could be observed in analyses of single-crystal diffuse-scattering (SCDS) data.…”

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confidence: 99%

Challenges in the structural science of materials

Catlow

2016

Int Union Crystallogr J

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The articles published recently in IUCrJ continue to exemplify the developments and challenges in the structural science of materials. They illustrate the exciting rapid developments in technique, sources, instrumentation and data analysis, the continuing role and growing power of computation in the field, and the increasing ability to investigate complex structural problems in materials that are of direct relevance to their function.Advances in technique and data analysis are well illustrated by the review article of Van Aert et al. (2016) which describes how developments in transmission electron microscopy coupled with novel data analysis methods can give accurate structural information on nanostructured and disordered materials; and illustrates how increased precision can be achieved in atomic positions using these techniques. Several examples illustrate the power of the approach, for example the accurate information on atomic coordinates adjacent to a twin boundary in CaTiO 3 , as illustrated in Fig. 1.Significant developments in techniques are also described in the article of Rius et al. (2015), who describe how the synchrotron-based through-the-substrate X-ray microdiffraction technique (tts-XRD) can now be used to obtain structural information on microvolumes of crystals embedded in a complex matrix -a development of importance for several areas of materials science including the study of complex mineralogical samples. The use of synchrotron radiation in operando methods in structural science, particularly relating to catalytic systems, continues to grow as illustrated by the recent study of Lezcano-Gonzá lez et al. (2016) who investigated complex structural changes during the operation of a microporous dehydroaromatization catalyst.A core area of crystallography is of course the determination and modelling of electron density, recent developments in which are discussed in the article of Macchi et al. (2015), who emphasize multi-technique approaches, and show the importance of developments in sources and detectors and of new multipole models for describing charge densities accurately. Related topics are considered in the article of Sanjuan-Szklarz et al. (2016), which discusses how improved accuracy may be obtained by using transferable aspherical atom models (TAAM) in structure refinements and how such an approach can yield highquality structures even from low-resolution data.

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Total scattering and pair distribution function analysis in modelling disorder in PZN (PbZn_1/3Nb_2/3O₃)

Cited by 14 publications

References 32 publications

Using powder XRD and pair distribution function to determine anisotropic atomic displacement parameters of orthorhombic tridymite and tetragonal cristobalite

Using powder XRD and pair distribution function to determine anisotropic atomic displacement parameters of orthorhombic tridymite and tetragonal cristobalite

Monte Carlo Modelling of Single-Crystal Diffuse Scattering from Intermetallics

Challenges in the structural science of materials

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