Atomistic calculations of charged point defects at grain boundaries in 
SrTiO3

The electrical properties of SrTiO3 (strontium titanate) ceramics are strongly influenced or even dictated by grain boundary segregation of charged point defects, such as dopant atoms, impurities, vacancies, or self-interstitials. The atomistic structure of the grain boundaries, their energy, and the segregation of point defects mutually depend on each other. Grain boundary segregation of charged point defects induces the formation of space charge layers in the adjoining crystals. In order to investigate the relation between grain boundary structure and composition, grain boundaries in Fedoped SrTiO3 bicrystals and in SrTiO3 ceramics were studied by HRTEM and by AEM with subnanometer resolution.Quantitative HRTEM served to investigate the atomistic structure of Σ=3, (111) grain boundaries in Fe-doped SrTiO3 bicrystals with a doping level of Fe/Ti= 0.04at% (Fig. 1). Analysis of the translation state revealed that the Σ=3, (111) grain boundary has an excess volume: normal to the boundary plane, the spacing between the two crystals exceeds what one would expect from a coincidence site lattice model by (0.06 ±0.01 )nm.

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Stability of point defects near MgO grain boundaries in FeCoB/MgO/FeCoB magnetic tunnel junctions

Physical Review Materials ◽

10.1103/physrevmaterials.2.125002 ◽

2018 ◽

Vol 2 (12) ◽

Cited By ~ 3

Author(s):

Jonathan J. Bean ◽

Keith P. McKenna

Keyword(s):

Grain Boundaries ◽

Point Defects ◽

Tunnel Junctions ◽

Magnetic Tunnel Junctions

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Disordering and grain boundaries of (Ni,Fe)Cr2O4 spinels from atomistic calculations

The Journal of Chemical Physics ◽

10.1063/1.4822262 ◽

2013 ◽

Vol 139 (13) ◽

pp. 134702 ◽

Cited By ~ 3

Author(s):

Alain Chartier ◽

Bogdan Golovchuk ◽

Stéphane Gossé ◽

Laurent Van Brutzel

Keyword(s):

Grain Boundaries ◽

Atomistic Calculations

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Antagonist effects of grain boundaries between the trapping process and the fast diffusion path in nickel bicrystals

Scientific Reports ◽

10.1038/s41598-021-94107-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

J. Li ◽

A. Hallil ◽

A. Metsue ◽

A. Oudriss ◽

J. Bouhattate ◽

...

Keyword(s):

Grain Boundaries ◽

Hydrogen Diffusion ◽

Short Circuit ◽

Diffusion Path ◽

Fast Diffusion ◽

Fundamental Parameters ◽

Segregation Energy ◽

Atomistic Calculations ◽

And Migration ◽

Trapping Process

AbstractHydrogen-grain-boundaries interactions and their role in intergranular fracture are well accepted as one of the key features in understanding hydrogen embrittlement in a large variety of common engineer situations. These interactions implicate some fundamental processes classified as segregation, trapping and diffusion of the solute which can be studied as a function of grain boundary configuration. In the present study, we carried out an extensive analysis of four grain-boundaries based on the complementary of atomistic calculations and experimental data. We demonstrate that elastic deformation has an important contribution on the segregation energy which cannot be simply reduced to a volume change and need to consider the deviatoric part of strain. Additionally, some significant configurations of the segregation energy depend on the long-range elastic distortion and allows to rationalize the elastic contribution in three terms. By investigating the different energy barriers involved to reach all the segregation sites, the antagonist impact of grain boundaries on hydrogen diffusion and trapping process was elucidated. The segregation energy and migration energy are two fundamental parameters in order to classify the grain-boundaries as a trapping location or short circuit for diffusion.

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