A novel mechanism to reduce coercive field of ferroelectric materials via {1 1 1} twin engineering

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 {1 1 1} 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.

本研究提出了一种基于晶体孪晶工程（crystal twin engineering）的全新策略，用以提升铁电体整体体系内的畴变体（domain variants）总量——该策略通过增加每个孪晶晶粒内的铁电畴变体数目实现，并以多晶钛酸钡（barium titanate）薄膜验证了该策略的有效性。研究开发了一种新型热机械处理工艺，可在不同孪晶密度的薄膜中引入{111}纳米孪晶。实验结果表明，高孪晶密度样品的矫顽场（coercive field）较低孪晶密度样品低32%。所开展的相场模拟（phase field simulations）定性验证了上述实验结果。此外，高孪晶密度样品的表观饱和极化强度较低孪晶密度样品高72%。孪晶工程可推广应用于所有铁电陶瓷与薄膜，以大幅提升其性能。