Theory of ferroelectricity in the tetragonal phase of pure and Co-Doped BaTiO₃ due to the lattice deformation

Abstract

The ferroelectricity in the tetragonal phase of pure and Co-doped BaTiO₃, BaTiO₃:Co, is discussed quantitatively from the dipole-dipole interaction caused by the strong local field acting on the constituent ions. In this microscopic model, only the Ti ions situated at the center of the lattice are assumed to have the spontaneous shift. The ferroelctric-paraelectric phase transition in BaTiO₃ is also analyzed. It is found that the ferroelectricity and the order of the phase transition in BaTiO₃ are in good agreement with the experimental data.