First-principles study of the ordered structures of the single crystal PMN(0.75)-PT(0.25) and their ferroelectric characteristics

Abstract

For the various PMN(0.75)-PT(0.25) ordered structures, first principles density functional studies using local density approximation (LDA) framework and augmented projected augmented wave (PAW) pseudopotentials. All possible 20-atom ordering along the [001]-, [011]- and [111]- directions are considered in the ab-initio code VASP. Also, we conducted linear response with density functional perturbation theory (DFPT) which is implemented in the VASP to compute the electronic dielectric tensors and piezoelectric tensors. The polar response is strongly dependent of the ionic ordering. Some PMN(0.75)-PT(0.25) ordered structures show strong piezoelectric characteristics.