Abstract:

Using the firstprinciples calculation, we  studied the 180° domain in the ferroelectric material of KNbO₃ and calculated the thickness, energy and barrier height for the coherent motion of the domain wall of both K centered and Nb centered domain walls. Our calculation reveals that the thickness of 180° domain wall is only one to two lattice constants. The K centered domain wall is preferred because its formation energy (7.58 mJ/m²) is half of t
hat of the Nb centered domain wall (15.16 mJ/m²). The Nb centered domain wall is unstable and will gradually change to the K centered domain wall. The arrier height for the coherent motion of the domain wall to its neighboring lattice position is 7.58 mJ/m².

Key words: KNbO₃, ferroelectric, domain wall