Investigating Grain Boundary Structures and Energetics of Rutile with Reactive Molecular Dynamics

PJ Shamberger and JL Wohlwend and AK Roy and AA Voevodin, JOURNAL OF PHYSICAL CHEMISTRY C, 120, 13049-13062 (2016).

DOI: 10.1021/acs.jpcc.6b02695

Determining quantitative grain boundary (GB) energies as a function of microscopic orientation parameters is essential in order to understand the population of boundaries present in polycrystalline ceramics and films, and the physical properties that result from these boundaries. Here, we investigate the use of two reactive potentials, COMB3 and ReaxFF, to predict free surface and grain boundary structures and energies in the TiO2 rutile system, and compare these results against previously reported ab initio surface and interfacial energies. We demonstrate reactive MD potentials to be generally capable of reproducing key features anticipated for GB structures and energetics, including relative GB and surface energy, charge distributions and potential for different polar and nonpolar terminations, and energy cusps at low-energy interfaces (e.g., coherent twin boundaries, coherent site lattice boundaries). This work establishes the foundation for further use of reactive MD to simulate libraries of oxide GBs and dynamic processes occurring along those GBs.

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