A common theory of line broadening and rocking curves

Zilahi, Gyula; Ungár, Tamás; Tichy, G.

doi:10.1107/s1600576715001466

Cited by 26 publications

(15 citation statements)

References 65 publications

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“…The first is to find an approach of assembling inhomogeneous strains into a nanostructure; and the second is to make these complex strains precisely measured. To quantitatively measure an inhomogeneous strain is always a great challenge, since peak broadening in diffraction experiments results from not only inhomogeneous strains but also a number of other components such as crystallographic defects, refined grains and similarly orientated domains 35 .…”

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confidence: 99%

Giant linear strain gradient with extremely low elastic energy in a perovskite nanostructure array

et al. 2017

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Although elastic strains, particularly inhomogeneous strains, are able to tune, enhance or create novel properties of some nanoscale functional materials, potential devices dominated by inhomogeneous strains have not been achieved so far. Here we report a fabrication of inhomogeneous strains with a linear gradient as giant as 106 per metre, featuring an extremely lower elastic energy cost compared with a uniformly strained state. The present strain gradient, resulting from the disclinations in the BiFeO3 nanostructures array grown on LaAlO3 substrates via a high deposition flux, induces a polarization of several microcoulomb per square centimetre. It leads to a large built-in electric field of several megavoltage per metre, and gives rise to a large enhancement of solar absorption. Our results indicate that it is possible to build up large-scale strain-dominated nanostructures with exotic properties, which in turn could be useful in the development of novel devices for electromechanical and photoelectric applications.

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confidence: 99%

Giant linear strain gradient with extremely low elastic energy in a perovskite nanostructure array

et al. 2017

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“…References 5, 15, and 20, the concrete values of dislocation densities cannot be determined from such slopes. [23,29,30,73,74] A large number of investigations proved that the breadths and shape of line profiles depend on the coupled values of the number density, q, and the effective outer cut-off radius, R e , of dislocations. [23,29,30,38,39,41,43,[47][48][49][50][51] These two parameters determine the distortion distribution function, f(g), derived by Wilkens.…”

Section: A Strain Distribution In the Near Gb Regionmentioning

confidence: 99%

Dislocations in Grain Boundary Regions: The Origin of Heterogeneous Microstrains in Nanocrystalline Materials

Zhang

Ódor

Farkas

et al. 2019

Metall Mater Trans A

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Nanocrystalline materials reveal excellent mechanical properties but the mechanism by which they deform is still debated. X-ray line broadening indicates the presence of large heterogeneous strains even when the average grain size is smaller than 10 nm. Although the primary sources of heterogeneous strains are dislocations, their direct observation in nanocrystalline materials is challenging. In order to identify the source of heterogeneous strains in nanocrystalline materials, we prepared Pd-10 pct Au specimens by inert gas condensation and applied high-pressure torsion (HPT) up to c @ 21. High-resolution transmission electron microscopy (HRTEM) and molecular dynamic (MD) simulations are used to investigate the dislocation structure in the grain interiors and in the grain boundary (GB) regions in the as-prepared and HPT-deformed specimens. Our results show that most of the GBs contain lattice dislocations with high densities. The average dislocation densities determined by HRTEM and MD simulation are in good correlation with the values provided by X-ray line profile analysis. Strain distribution determined by MD simulation is shown to follow the Krivoglaz-Wilkens strain function of dislocations. Experiments, MD simulations, and theoretical analysis all prove that the sources of strain broadening in X-ray diffraction of nanocrystalline materials are lattice dislocations in the GB region. The results are discussed in terms of misfit dislocations emanating in the GB regions reducing elastic strain compatibility. The results provide fundamental new insight for understanding the role of GBs in plastic deformation in both nanograin and coarse grain materials of any grain size.

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“…Powder X-ray diffraction was recorded for our samples using a Rigaku MiniFlex II desktop X-ray diffractometer to identify the microstructural changes that occurred in the polymer matrix as a result of doping, and these changes were evaluated using the whole powder pattern fitting (WPPF) method (Scardi & Leoni, 2006;Balzar et al, 2004;Koker et al, 2014;Zilahi et al, 2015). Measurements were recorded at an output of 30 kV and 15 mA of Cu K radiation for a scanning angle between 6 and 60 , with a speed of 5 min À1 and a step size of 0.02 .…”

Section: Microstructural Changes Observed With X-ray Diffractionmentioning

confidence: 99%

Functional data analysis techniques for the study of structural parameters in polymer composites

et al. 2016

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This article presents a novel method, based on functional data analysis, to analyse measurements of structural parameters of polymers and polymer composites. The method is demonstrated using newly developed biodegradable conducting polymer composites prepared via a solution casting technique. The measurements of the macro-and microstructural parameters that are used in the characterization of these films are obtained using X-ray diffraction, an impedance analyser and a UV-vis spectrometer. A functional representation of the measured values of the parameters at different dopant concentrations is adopted by viewing them as realizations of a continuous-time stochastic process observed with measurement error. This allows one to estimate the mean functional relationship between a parameter and the dopant concentration. A functional version of principal component analysis is performed, by which the major modes of variation are discovered and the correlations of parameter values at different concentrations are estimated. This provides insight into local and global features of the relationship between these parameters. Some comments are made on how the parameters vary as a function of dopant concentration. research papers J. Appl. Cryst. (2016). 49, 594-605 Thejas Gopal Krishne Urs et al. Functional data analysis techniques 595

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A common theory of line broadening and rocking curves

Cited by 26 publications

References 65 publications

Giant linear strain gradient with extremely low elastic energy in a perovskite nanostructure array

Giant linear strain gradient with extremely low elastic energy in a perovskite nanostructure array

Dislocations in Grain Boundary Regions: The Origin of Heterogeneous Microstrains in Nanocrystalline Materials

Functional data analysis techniques for the study of structural parameters in polymer composites

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