Diffraction line profiles from polydisperse crystalline systems

Scardi, Paolo; Leoni, Matteo

doi:10.1107/s0108767301008881

Cited by 207 publications

(165 citation statements)

References 13 publications

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“…The specimen broadening function used was specific to modeling of cylinders of constant aspect ratio with a distribution of diameters presumed to be log-normal. A numerical approach, based on the model for cylinders proposed by Langford & Louër (1982) and the distribution treatment of Scardi & Leoni (2001) and Leoni & Scardi (2004), was employed to calculate the profile for the distributed domains. The Warren (1969) model for hexagonal stacking faults was used.…”

Section: Methodsmentioning

confidence: 99%

Crystalline domain size and faulting in the new NIST SRM 1979 zinc oxide

et al. 2013

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A NIST SRM certified to address the issue of crystallite size measurement through a line profile analysis has been under development for several years. In order to prepare the feedstock for the SRM, nano-crystalline zinc oxide was produced from thermal decomposition of zinc oxalate.The thermal processing parameters were chosen to yield particles in two size ranges, one with a distribution centered at approximately 15 nm and another centered at 60 nm. Certification data were collected on a NIST-built diffractometer equipped with a Johansson incident beam monochromator and scintillation detector. Data were analyzed using whole powder pattern modeling to determine microstructural data. The analysis shows domains to be in the form of discs of a fairly small aspect ratio. While both materials exhibit the effects of stacking faults through broadening of specific hkl reflections, their presence in the 60 nm is more difficult to discern. Images of the crystallites obtained with transmission electron microscopy are consistent with the results from the X-ray diffraction analyses.

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Section: Methodsmentioning

confidence: 99%

Crystalline domain size and faulting in the new NIST SRM 1979 zinc oxide

et al. 2013

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“…Among the most frequently implemented models, finite size and shape of the crystalline domain, dislocations of different type and stacking faults. [10,22,23] The key to use a convolution of effects is to exploit the convolution theorem for Fourier Transforms, which turns a computationally complex problem of folding into a simple multiplication of different terms. As of the most recent developments, [24] WPPM can use virtually any crystalline domain shape and strain models for dislocations in any crystal system.…”

Section: B Whole Powder Pattern Modeling (Wppm) and Dsementioning

confidence: 99%

On the Modeling of the Diffraction Pattern from Metal Nanocrystals

Gelisio

Scardi

2014

Metall Mater Trans A

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The powder diffraction patterns of spherical nanocrystals made of five different fcc metals were generated using atomistic models within a Molecular Dynamics simulation. Static and dynamic effects are interpreted and discussed within the framework of two different approaches, respectively, based on (1) a Reciprocal Space and (2) a Direct Space representation of diffraction. Chosen elements display a wide range of properties, especially related to material stiffness and elastic anisotropy, so to deeply challenge interpretation paradigms. The effect of the shape on static and dynamic features is also addressed.

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“…For polydisperse crystallites L is determined by the ratio of the fourth and third moments of the size distribution function in the way (Scardi & Leoni, 2001):…”

Section: Experimental Aspects: Liquid Dispersions Of Detonation Nanodmentioning

confidence: 99%

Small-angle scattering from polydisperse particles with a diffusive surface

et al. 2014

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Small-angle scattering from polydisperse particles with a diffusive surfaceIn: Journal of Applied Crystallography (2014) Blackwell DOI: 10.1107/S1600576714001216Person to contact for this submission: Mikhail Avdeev (avd@nf.jinr.ru; phone: (+7-49621) 62-674; fax: (+7-49621) SynopsisSmall-angle scattering from polydisperse non-homogeneous particles with diffusive interface is considered for the case of small diffusivity. The deduced simplifications both in the analysis of polydispersity and inner structure (contrast variation) of the particles are used in the treatment of the small-angle neutron scattering data from liquid dispersions of detonation nanodiamonds. AbstractThe particles with a diffusive surface, which is characterized by a deviation from the Porod power-law asymptotic behavior in small-angle scattering towards the exponent below 4, are considered with respect to the polydispersity problem. The case of small diffusivity is emphasized, which allows one to describe the scattering length density distribution within the spherically isotropic particles in terms of a continuous profile. This significantly simplifies the analysis of the particle size distribution function, as well as the change in the scattering invariants under contrast variation. The effect of the solvent scattering contribution on the apparent exponent value in the power-law type scattering and related restrictions in the analysis of the scattering curves are discussed. The principal features and possibilities of the developed approach are illustrated in the treatment 2 of the experimental small-angle neutron scattering data from liquid dispersions of detonation nanodiamonds.The obtained scattering length density profile of the particles fits well a transition of the diamond states of carbon inside the crystallites to graphite-like states at the surface and makes it possible to combine the diffusive properties of the surface with the experimental shift of the mean scattering length density of the particles as compared to that of pure diamond. The moments of the particle size distribution are derived and analyzed in terms of the lognormal approximation.

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Diffraction line profiles from polydisperse crystalline systems

Cited by 207 publications

References 13 publications

Crystalline domain size and faulting in the new NIST SRM 1979 zinc oxide

Crystalline domain size and faulting in the new NIST SRM 1979 zinc oxide

On the Modeling of the Diffraction Pattern from Metal Nanocrystals

Small-angle scattering from polydisperse particles with a diffusive surface

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