Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 8, Issue 19, Pages 12246-12256Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.5b12574
Keywords
SrTiO3; dislocation; oxygen diffusion; MD simulations; resistive switching
Funding
- German Science Foundation (DFG) within the collaborative research centre, Nanoswitches [SFB 917]
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We used classical molecular-dynamics simulations to study the atomistic structure of, and the diffusion of oxygen ions along, the periodic array of edge dislocations comprising a symmetrical 6.0 degrees [100] tilt grain boundary in SrTiO3. The results indicate that, at elevated temperatures, the two types of dislocation core (TiO2-type and SrO-type) that make up the boundary are stable and that oxygen-deficient cores maintain their dissociated structures. They also confirm that oxygen vacancies prefer to reside at the cores rather than in the bulk. Tracer diffusion coefficients of oxygen were obtained for oxygen-deficient bulk and grain-boundary simulation cells at temperatures in the range of 1000 <= T/K <= 2300. Calculated values of the oxygen-vacancy diffusion coefficient for the bulk phase agree extremely well with published experimental data. Tracer diffusion coefficients obtained for the grain-boundary cell are, in comparison to those for the bulk, lower in magnitude and have a higher activation enthalpy, indicating that, relative to the bulk, the migration of oxygen ions along a[100] dislocation cores in SrTiO3 is hindered. These results provide further support for the decoupled model of filament formation in resistively switching SrTiO3.
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