Computer simulation of the cluster structure of an oxygen-octahedral lithium niobate crystal

We have performed a computer simulation of processes taking place at formation of energetic equilibrium oxygen-octahedral clusters in a ferroelectric phase of a stoichiometric lithium niobate crystal (LN, LiNbO3). In order to do so we used a semiclassical atomistic model with a qualitative approach. For the first time we have modeled lithium niobate structure on the basis of oxygen octahedra, while unit cell are usually used. We have established that there is an energy efficient cluster size with a specific structure that approaches a congruent LN structure. We have also proved that stoichiometric composition of LN leads to loss of electrical neutrality; thus achievement of demanded properties including photorefractive ones is possible by doping. We have chosen an ion with a charge 3+ to build a model.