Regensburg 2022 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 24: Non-equilibrium Phenomena in Materials Induced by Electrical and Magnetic Fields 4
MM 24.3: Talk
Wednesday, September 7, 2022, 16:30–16:45, H45
Atomistic calculations of charged point defects at grain boundaries in SrTiO3 — •Cong Tao1, Daniel Mutter1, Daniel Urban1, and Christian Elsässer1,2 — 1Fraunhofer IWM, Freiburg, Germany — 2University of Freiburg, FMF, Germany
Oxygen vacancies have been identified to play an important role in accelerating grain growth in polycrystalline perovskite-oxide ceramics. To advance the fundamental understanding of growth mechanisms at the atomic scale, we performed classical atomistic simulations to investigate the atomistic structures and oxygen vacancy formation energies at grain boundaries in the prototypical perovskite-oxide material SrTiO3 [1]. We focus on two symmetric tilt grain boundaries, namely Σ5(310)[001] and Σ5(210)[001]. Electrostatic potentials are present in supercells containing alternatingly charged lattice planes and grain boundaries. We derive analytic solutions for these potentials for both open and periodic boundary conditions and apply them to our atomistic model structures. In this way, simulation artifacts resulting from the interaction of the electrostatic potential with charged point defects can be corrected, leading to physically reasonable defect energies. We report calculated formation energies of oxygen vacancies on all possible sites across boundaries between the two misoriented grains, and we analyze the values with respect to local charge densities at the vacant sites. The developed calculation procedure can be transferred to more complicated interfaces such as asymmetric tilt grain boundaries [2].
[1] C. Tao, et. al., Phys. Rev. B 104, 054114 (2021).
[2] C. Tao, et. al., arxiv.org/abs/2110.02118.