LATTICE STRUCTURE OF (100) FREE SURFACE OF BARIUM TITANATE

The lattice structure of the (100) BaTiO3 surface has been examined. The deformations of the lattice due to the termination of the lattice at the surface were assumed to be restricted to the outermost layer, and the polarization of the surface cations was neglected. The equilibrium configuration was then obtained by equating forces on a negative and on a positive surface ion to zero and expressing the induced dipole moment on the negative ion in terms of the electric field and polarizability of the negative ion. The solution of the resulting equations was computed by the Linear Iteration method. The surface cation and anion were found to be displaced ~ 0.23 Å and ~ - 0.021 Å respectively towards the lattice, and the dipole moment associated with the negative surface ion is ~ 1.34 D, with its negative end pointing towards the lattice. It was found that the dipole moment associated with the displacements of ions overrides the effects of their polarization and results in a net moment in the opposite direction. © 1968.