Molecular Dynamics Modeling of Nanoscale CaF2/BaF2 Heterolayer Structures

We present a transferable technique for the preparation of atomistic models mimicking ion conductor heterolayers grown by molecular beam epitaxy. On this basis, CaF2/BaF2 sandwich structures involving (100), (110), and (111.) interfaces were explored. Our molecular dynamics simulations reveal a close interplay of interface-driven lattice deformation and resulting dislocations with the fluoride ion redistribution and local conductivity. From this, an interfacial core region of about 1 nm thickness can be assessed, accompanied by a space charge zone in BaF2 that is, however, three times thicker. Significant conductivity effects owing to charge carrier redistribution are found, which are closely related to the experimental results on this system.