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Machine learning models based on convolutional neural networks have been used for predicting space groups of crystal structures from their atomic pair distribution function (PDF). However, the PDFs used to train the model are calculated using a fixed set of parameters that reflect specific experimental conditions, and the accuracy of the model when given PDFs generated with different choices of these parameters is unknown. In this work, the results of the top‐1 accuracy and top‐6 accuracy are robust when applied to PDFs of different choices of experimental parameters rmax, Qmax, Qdamp and atomic displacement parameters. [ABSTRACT FROM AUTHOR]

The use of the non‐negative matrix factorization (NMF) technique is validated for automatically extracting physically relevant components from atomic pair distribution function (PDF) data from time‐series data such as in situ experiments. The use of two matrix‐factorization techniques, principal component analysis and NMF, on PDF data is compared in the context of a chemical synthesis reaction taking place in a synchrotron beam, applying the approach to synthetic data where the correct composition is known and on measured PDFs from previously published experimental data. The NMF approach yields mathematical components that are very close to the PDFs of the chemical components of the system and a time evolution of the weights that closely follows the ground truth. Finally, it is discussed how this would appear in a streaming context if the analysis were being carried out at the beamline as the experiment progressed. [ABSTRACT FROM AUTHOR]

sasPDF, a method for characterizing the structure of nanoparticle assemblies (NPAs), is presented. The method is an extension of the atomic pair distribution function (PDF) analysis to the small‐angle scattering (SAS) regime. The PDFgetS3 software package for computing the PDF from SAS data is also presented. An application of the sasPDF method to characterize structures of representative NPA samples with different levels of structural order is then demonstrated. The sasPDF method quantitatively yields information such as structure, disorder and crystallite sizes of ordered NPA samples. The method was also used to successfully model the data from a disordered NPA sample. The sasPDF method offers the possibility of more quantitative characterizations of NPA structures for a wide class of samples. [ABSTRACT FROM AUTHOR]

This article demonstrates spatial mapping of the local and nanoscale structure of thin film objects using spatially resolved pair distribution function (PDF) analysis of synchrotron X‐ray diffraction data. This is exemplified in a lab‐on‐chip combinatorial array of sample spots containing catalytically interesting nanoparticles deposited from liquid precursors using an ink‐jet liquid‐handling system. A software implementation is presented of the whole protocol, including an approach for automated data acquisition and analysis using the atomic PDF method. The protocol software can handle semi‐automated data reduction, normalization and modeling, with user‐defined recipes generating a comprehensive collection of metadata and analysis results. By slicing the collection using included functions, it is possible to build images of different contrast features chosen by the user, giving insights into different aspects of the local structure. [ABSTRACT FROM AUTHOR]

Temperature is a ubiquitous environmental variable used to explore materials structure, properties and reactivity. This article reports a new paradigm for variable‐temperature measurements that varies the temperature continuously across a sample such that temperature is measured as a function of sample position and not time. The gradient approach offers advantages over conventional variable‐temperature studies, in which temperature is scanned during a series measurement, in that it improves the efficiency with which a series of temperatures can be probed and it allows the sample evolution at multiple temperatures to be measured in parallel to resolve kinetic and thermodynamic effects. Applied to treat samples at a continuum of temperatures prior to measurements at ambient temperature, the gradient approach enables parametric studies of recovered systems, eliminating temperature‐dependent structural and chemical variations to simplify interpretation of the data. The implementation of spatially resolved variable‐temperature measurements presented here is based on a gradient‐heater design that uses a 3D‐printed ceramic template to guide the variable pitch of the wire in a resistively heated wire‐wound heater element. The configuration of the gradient heater was refined on the basis of thermal modelling. Applications of the gradient heater to quantify thermal‐expansion behaviour, to map metastable polymorphs recovered to ambient temperature, and to monitor the time‐ and temperature‐dependent phase evolution in a complex solid‐state reaction are demonstrated. [ABSTRACT FROM AUTHOR]