A novel mechanism to reduce coercive field of ferroelectric materials via {111} twin engineering

The switchability of domains is essential for a wide range of applications of ferroelectrics and piezoelectrics. Unfortunately, the morphotropic phase boundary which is one of the most successful strategies to improve it only exists in few selected systems. Here we propose an alternative strategy that works for any systems, based on {111} twin engineering which increases the number of domain variants. [Display omitted] In the present work, we proposed a new strategy to increase the domain variants within the entire body of ferroelectrics, based on crystal twin engineering that increases the number of ferroelectric variants within each twinned grain, and demonstrated this strategy with polycrystalline barium titanate films. A novel thermomechanical treatment technique was developed to introduce {111} nanotwins into the films with different twin densities. The experimental results show that the coercive field is 32% lower in the high twin density samples than that in the low twin density ones. The conducted phase field simulations qualitatively confirmed the experimental results. Furthermore, the magnitude of the apparent saturation polarization is 72% higher in the high twin density samples than that in the low twin density samples. Twin engineering might be applied universally to all ferroelectric ceramics and films to substantially enhance their performance.