Ab initio study of dipolar defects and 180° domain walls in PbTiO3 Original Research Article

We have calculated the electronic and ionic structures for oxygen-vacancy–impurity-metal complexes and 180° domain walls in PbTiO3 using a first-principles total energy method. The binding energy of an oxygen vacancy to a Pt impurity in PbTiO3 is calculated to be ∼3.0 eV. The complex is strongly polar, stabilized by electron capture, and pins the polarization of the surrounding lattice. Domain walls are found to be Pb-centered and extremely narrow with a width of only about two lattice constants. The energy density of a domain wall is calculated to be ∼150 erg/cm2.