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Static and dynamic atom displacements in nanocrystalline powders from diffraction analysis at finite temperature

Title	Static and dynamic atom displacements in nanocrystalline powders from diffraction analysis at finite temperature
Author	Ozturk, Hande, Erucar, Ilknur, Batyrow, Merdan
Publication Date:	2024-05
Publication Place	- Elsevier
Subject	Rietveld refinement, Thermal diffuse scattering, Molecular dynamics simulations, Size effects, X-ray diffraction, Nanoparticles
Type	Periodical
Language	English
Digital	Yes
Manuscript	No
Library:	Özyeğin University
Library Asset ID	2589-1529
Record ID	3d56ed9b-8b92-4abb-8c80-caef58853c48
Library Location	Mechanical Engineering, Natural and Mathematical Sciences
Date	2024-05
Notes	TÜBİTAK
Sample Text	We evaluate the accuracy of x-ray diffraction analysis performed by Rietveld refinement in extracting the static and dynamic atomic displacement parameters of spherical gold nanocrystals with sizes of 30 nm and below and within a temperature interval of 10-300 K. A self-consistent computational workflow composed of real- and reciprocal- space analyses is designed for this purpose. We obtain average lattice parameters, static and thermal atomic displacements as well as their temperature and particle size dependence in an ideally monodispersed and realistic nanocrystalline powder generated by molecular dynamics simulations. Then, we compare crystallographic parameters obtained from real- and reciprocal- space analyses to evaluate the accuracy of diffraction analysis. We also extend the comparison to local variations of crystallographic parameters in the nanocrystals and show how Rietveld refinement relates to the average parameters of the core and surface regions separately. We show that 1) average lattice parameters obtained from Rietveld refinement are greater than the mean lattice parameter of small nanocrystals and converge to the core lattice parameter with increasing particle size, 2) Rietveld refinement significantly underestimates static atom displacements of surface atoms in small nanocrystals, 3) dynamic atomic displacements in nanocrystalline gold powders are reliably obtained within 5 % error by Rietveld refinement, provided that thermal diffuse scattering is adequately removed from the diffraction data, 4) the discrepancy between real- and reciprocal-space analysis increases for the smallest gold nanocrystal.
DOI	10.1016/j.mtla.2024.102099
Cilt	34

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Özyeğin University

Static and dynamic atom displacements in nanocrystalline powders from diffraction analysis at finite temperature

Author Ozturk, Hande, Erucar, Ilknur, Batyrow, Merdan

Publication Date 2024-05

Publication Place - Elsevier

Subject Rietveld refinement, Thermal diffuse scattering, Molecular dynamics simulations, Size effects, X-ray diffraction, Nanoparticles

Type Periodical

Language English

Digital Yes

Manuscript No

Library Özyeğin University

Library Asset ID 2589-1529

Record ID 3d56ed9b-8b92-4abb-8c80-caef58853c48

Library Location Mechanical Engineering, Natural and Mathematical Sciences

Date 2024-05

Notes TÜBİTAK

Sample Text We evaluate the accuracy of x-ray diffraction analysis performed by Rietveld refinement in extracting the static and dynamic atomic displacement parameters of spherical gold nanocrystals with sizes of 30 nm and below and within a temperature interval of 10-300 K. A self-consistent computational workflow composed of real- and reciprocal- space analyses is designed for this purpose. We obtain average lattice parameters, static and thermal atomic displacements as well as their temperature and particle size dependence in an ideally monodispersed and realistic nanocrystalline powder generated by molecular dynamics simulations. Then, we compare crystallographic parameters obtained from real- and reciprocal- space analyses to evaluate the accuracy of diffraction analysis. We also extend the comparison to local variations of crystallographic parameters in the nanocrystals and show how Rietveld refinement relates to the average parameters of the core and surface regions separately. We show that 1) average lattice parameters obtained from Rietveld refinement are greater than the mean lattice parameter of small nanocrystals and converge to the core lattice parameter with increasing particle size, 2) Rietveld refinement significantly underestimates static atom displacements of surface atoms in small nanocrystals, 3) dynamic atomic displacements in nanocrystalline gold powders are reliably obtained within 5 % error by Rietveld refinement, provided that thermal diffuse scattering is adequately removed from the diffraction data, 4) the discrepancy between real- and reciprocal-space analysis increases for the smallest gold nanocrystal.

DOI 10.1016/j.mtla.2024.102099

Cilt 34