Recrystallization, Phase Composition, and Local Structure of Amorphous Lactose from the Total Scattering Pair Distribution Function

2015 ◽  
Vol 16 (1) ◽  
pp. 210-220 ◽  
Author(s):  
Maxwell W. Terban ◽  
Eugene Y. Cheung ◽  
Paul Krolikowski ◽  
Simon J. L. Billinge
Keyword(s):  
Distribution Function ◽  
Phase Composition ◽  
Local Structure ◽  
Pair Distribution Function ◽  
Total Scattering ◽  
Amorphous Lactose

scholarly journals Demonstration of thin film pair distribution function analysis (tfPDF) for the study of local structure in amorphous and crystalline thin films

IUCrJ ◽  
2015 ◽  
Vol 2 (5) ◽  
pp. 481-489 ◽  
Author(s):  
Kirsten M. Ø. Jensen ◽  
Anders B. Blichfeld ◽  
Sage R. Bauers ◽  
Suzannah R. Wood ◽  
Eric Dooryhée ◽  
...  
Keyword(s):  
Thin Films ◽  
Distribution Function ◽  
Structure Analysis ◽  
Local Structure ◽  
Pair Distribution Function ◽  
High Energy ◽  
Scattering Data ◽  
X Rays ◽  
Amorphous Precursor ◽  
Total Scattering

By means of normal-incidence, high-flux and high-energy X-rays, total scattering data for pair distribution function (PDF) analysis have been obtained from thin films (tf), suitable for local structure analysis. By using amorphous substrates as support for the films, the standard Rapid Acquisition PDF setup can be applied and the scattering signal from the film can be isolated from the total scattering data through subtraction of an independently measured background signal. No angular corrections to the data are needed, as would be the case for grazing incidence measurements. The `tfPDF' method is illustrated through studies of as-deposited (i.e.amorphous) and crystalline FeSb3films, where the local structure analysis gives insight into the stabilization of the metastable skutterudite FeSb3phase. The films were prepared by depositing ultra-thin alternating layers of Fe and Sb, which interdiffuse and after annealing crystallize to form the FeSb3structure. The tfPDF data show that the amorphous precursor phase consists of corner-sharing FeSb6octahedra with motifs highly resembling the local structure in crystalline FeSb3. Analysis of the amorphous structure allows the prediction of whether the final crystalline product will form the FeSb3phase with or without excess Sb present. The study thus illustrates how analysis of the local structure in amorphous precursor films can help to understand crystallization processes of metastable phases and opens for a range of new local structure studies of thin films.

Engineering Porosity Through Defects in a Giant Pore Metal–Organic Framework

2020 ◽  
Author(s):  
Adam Sapnik ◽  
Duncan Johnstone ◽  
Sean M. Collins ◽  
Giorgio Divitini ◽  
Alice Bumstead ◽  
...  
Keyword(s):  
Distribution Function ◽  
Ball Milling ◽  
Local Structure ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Defect Engineering ◽  
Metal Organic ◽  
Unsaturated Metal Sites

<p>Defect engineering is a powerful tool that can be used to tailor the properties of metal–organic frameworks (MOFs). Here, we incorporate defects through ball milling to systematically vary the porosity of the giant pore MOF, MIL-100 (Fe). We show that milling leads to the breaking of metal–linker bonds, generating more coordinatively unsaturated metal sites, and ultimately causes amorphisation. Pair distribution function analysis shows the hierarchical local structure is partially</p><p>retained, even in the amorphised material. We find that the solvent toluene stabilises the MIL-100 (Fe) framework against collapse and leads to a substantial rentention of porosity over the non-stabilised material.</p>

scholarly journals Structural characterisation of amorphous solid dispersions via metropolis matrix factorisation of pair distribution function data

2019 ◽  
Vol 55 (89) ◽  
pp. 13346-13349 ◽  
Author(s):  
Harry S. Geddes ◽  
Helen Blade ◽  
James F. McCabe ◽  
Leslie P. Hughes ◽  
Andrew L. Goodwin
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Solid Dispersions ◽  
Complex Mixture ◽  
Amorphous Solid ◽  
Amorphous Solid Dispersions ◽  
Total Scattering ◽  
Structural Characterisation ◽  
Function Data ◽  
Matrix Factorisation

We use total scattering and non-negative matrix factorisation to characterise the structure of an amorphous pharmaceutical in a complex mixture.

scholarly journals Precise implications for real-space pair distribution function modeling of effects intrinsic to modern time-of-flight neutron diffractometers

2018 ◽  
Vol 74 (4) ◽  
pp. 293-307 ◽  
Author(s):  
Daniel Olds ◽  
Claire N. Saunders ◽  
Megan Peters ◽  
Thomas Proffen ◽  
Joerg Neuefeind ◽  
...  
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Amorphous Materials ◽  
Best Practice ◽  
Time Of Flight ◽  
Real Space ◽  
Mitigation Strategies ◽  
Total Scattering ◽  
Conventional Analysis ◽  
Pdf Analysis

Total scattering and pair distribution function (PDF) methods allow for detailed study of local atomic order and disorder, including materials for which Rietveld refinements are not traditionally possible (amorphous materials, liquids, glasses and nanoparticles). With the advent of modern neutron time-of-flight (TOF) instrumentation, total scattering studies are capable of producing PDFs with ranges upwards of 100–200 Å, covering the correlation length scales of interest for many materials under study. Despite this, the refinement and subsequent analysis of data are often limited by confounding factors that are not rigorously accounted for in conventional analysis programs. While many of these artifacts are known and recognized by experts in the field, their effects and any associated mitigation strategies largely exist as passed-down `tribal' knowledge in the community, and have not been concisely demonstrated and compared in a unified presentation. This article aims to explicitly demonstrate, through reviews of previous literature, simulated analysis and real-world case studies, the effects of resolution, binning, bounds, peak shape, peak asymmetry, inconsistent conversion of TOF to d spacing and merging of multiple banks in neutron TOF data as they directly relate to real-space PDF analysis. Suggestions for best practice in analysis of data from modern neutron TOF total scattering instruments when using conventional analysis programs are made, as well as recommendations for improved analysis methods and future instrument design.

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