Composition modulation away from the polar direction inPb(Sc,Nb)O3alloys

Abstract
A first-principles-derived approach is used to study properties of Pb(Sc,Nb)O3 alloys that are compositionally modulated along the [001] pseudocubic direction. The direction of the local electrical polarizations is found to be spatially-dependent, and can be adjusted with the modulation parameters. Furthermore, modulated structures with large composition gradients adopt a monoclinic phase—in which the total electrical polarization lies between the [111] and [110] directions—for their ferroelectric ground state, and exhibit large electromechanical responses.