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3D Dislocation Structure Evolution in Strontium Titanate: Spherical Indentation Experiments and MD Simulations

Javaid, Farhan and Stukowski, Alexander and Durst, Karsten (2016):
3D Dislocation Structure Evolution in Strontium Titanate: Spherical Indentation Experiments and MD Simulations.
In: Journal of the American Ceramic Society, pp. 1134-1145, 100, (3), ISSN 00027820, DOI: 10.1111/jace.14626, [Online-Edition: https://doi.org/10.1111/jace.14626],
[Article]

Abstract

In the present work, the dislocation structure evolution around and underneath the spherical indentations in (001) oriented single crystalline strontium titanate (STO) was revealed by using an etch-pit technique and molecular dynamics (MD) simulations. The 3D defect structure at various length scales and subsurface depths was resolved with the help of a sequential polishing, etching, and imaging technique. This analysis, combined with load-displacement data, shows that the incipient plasticity (manifested as sudden indenter displacement bursts) is strongly influenced by preexisting dislocations. In the early stage of plastic deformation, the dislocation pile-ups are all aligned in 〈100〉 directions, lying on {110}45 planes, inclined at 45° to the (001) surface. At higher mean contact pressure and larger indentation depth, however, dislocation pile-ups along 〈110〉 directions appear, lying on {110}90 planes, perpendicular to the (100) surface. MD simulations confirm the glide plane nature and provide further insights into the dislocation formation mechanisms by tracing the evolution of the complete dislocation line network as function of indentation depth.

Item Type: Article
Erschienen: 2016
Creators: Javaid, Farhan and Stukowski, Alexander and Durst, Karsten
Title: 3D Dislocation Structure Evolution in Strontium Titanate: Spherical Indentation Experiments and MD Simulations
Language: English
Abstract:

In the present work, the dislocation structure evolution around and underneath the spherical indentations in (001) oriented single crystalline strontium titanate (STO) was revealed by using an etch-pit technique and molecular dynamics (MD) simulations. The 3D defect structure at various length scales and subsurface depths was resolved with the help of a sequential polishing, etching, and imaging technique. This analysis, combined with load-displacement data, shows that the incipient plasticity (manifested as sudden indenter displacement bursts) is strongly influenced by preexisting dislocations. In the early stage of plastic deformation, the dislocation pile-ups are all aligned in 〈100〉 directions, lying on {110}45 planes, inclined at 45° to the (001) surface. At higher mean contact pressure and larger indentation depth, however, dislocation pile-ups along 〈110〉 directions appear, lying on {110}90 planes, perpendicular to the (100) surface. MD simulations confirm the glide plane nature and provide further insights into the dislocation formation mechanisms by tracing the evolution of the complete dislocation line network as function of indentation depth.

Journal or Publication Title: Journal of the American Ceramic Society
Volume: 100
Number: 3
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
11 Department of Materials and Earth Sciences > Material Science > Physical Metallurgy
Date Deposited: 27 Nov 2017 12:03
DOI: 10.1111/jace.14626
Official URL: https://doi.org/10.1111/jace.14626
Funders: The authors gratefully acknowledge the funding from the Deutscher Akademischer Austaus chdienst (FJ) and the Gauss Centre for Supercomputing (GCS) for providing computing time through the John von Neumann Institute for Computing on the GCS share of, the supercomputer JUQUEEN at Jülich Supercomputing Centre. The authors would also like to thank Prof. Dr. Karsten Albe of TU Darmstadt for helpful discussion and critical examination of the paper, and Dr. Eric Patterson of TU Darmstadt for providing, STO single crystals.
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