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Title: Eshelby twist and correlation effects in diffraction from nanocrystals

Molecular dynamics simulations were used to model the Eshelby dislocation inside Pd and Ir nanowires and to predict the powder diffraction pattern using the Debye scattering equation. We find that the ideal dislocation solution by Eshelby is in good agreement with the observed twist angle and deviatoric strain, even though it ignores both the splitting of the Eshelby dislocation into two partials and surface stress. Surface stress plays a significant role only for nanorods with small aspect ratio (∼1:1). We also find that Wilson's prediction on the diffraction peak broadening for the Eshelby dislocation is overestimated because it ignores the fact that the Eshelby twist relaxes the deviatoric strain. Moreover, the twist loosens the correlation along the nanorod, causing additional line profile broadening, which is read by diffraction as a decrease of coherent domain size when the total twist angle is bigger than 1.5°. Overall, our findings suggest a novel way to predict and analyze the dislocations as well as the resulting strain fields in the twisted nanocrystalline rods.
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento 38123 (Italy)
  2. Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-338 (Korea, Republic of)
  3. Department of Civil, Environmental and Mechanical Engineering, Laboratory of Bio-Inspired and Graphene Nanomechanics, Universita' di Trento, via Mesiano, 77, 38123 Trento (Italy)
  4. (Trento) (Italy)
  5. (United Kingdom)
Publication Date:
OSTI Identifier:
22402931
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 16; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 77 NANOSCIENCE AND NANOTECHNOLOGY; ASPECT RATIO; COMPUTERIZED SIMULATION; CORRELATIONS; CRYSTALS; DIFFERENTIAL EQUATIONS; DIFFRACTION; DISLOCATIONS; MOLECULAR DYNAMICS METHOD; NANOWIRES; PALLADIUM; POWDERS; PRASEODYMIUM; STRAINS; STRESSES; SURFACES