
Anna V. Kimmel*, Jorge Íñiguez, Markys G. Cain, and Peter V. Sushko
J. Phys. Chem. Lett., 2013, 4 (2), pp 333–337
An atomistic model of the SiO
2/BaTiO
3 interface was constructed using ab initio molecular dynamics. Analysis of its structure and electronic properties reveals that (i) the band gap at the stoichiometric SiO
2/BaTiO
3 interface is significantly smaller than those of the bulk BaTiO
3 and SiO
2, and (ii) the interface contains

5.5 nm
–2 oxygen vacancies (
V2+) in the outermost TiO
2 plane of the BaTiO
3 and

11 nm
–2 Si–O–Ti bonds resulting from breaking Si–O–Si and Ti–O–Ti bonds and subsequent rearrangement of the atoms. This structure gives rise to the interface polar region with positive and negative charges localized in the BaTiO
3 and SiO
2 parts of the interface, respectively. We propose that high dielectric response, observed experimentally in the SiO
2-coated nanoparticles of BaTiO
3, is due to the electron gas formed in oxygen-deficient BaTiO
3 and localized in the vicinity of the polar interface.