Oxygen polyhedral dipole-dipole interaction induced domain reconstruction and relaxor behaviors in layered perovskite films for dielectric energy storage.

We define AO12 and BO6 oxygen polyhedra in layered perovskite films as A–O* and B–O* polyhedral dipoles, respectively, which are responsible for the spontaneous polarization and the construction of domains. Based on the dipole–dipole interaction among such polyhedral dipoles, we propose and deduce the forming domain energy Gk, which decides the evolution of domains. Furthermore, A–O* polyhedral dipoles of three-layered Bi4Ti3O12 are regulated by respectively inserting two layers of SrTiO3 and Sr0.92Ba0.08TiO3 into it to form Sr2Bi4Ti5O18 (SBT) and Ba0.16Sr1.84Bi4Ti5O18 (BSBT) films. It is shown that the domains are reconstructed to form smaller domains due to the decrease of the forming domain energy, which is also embodied in the relaxor characteristics. Likewise, interestingly, the maximum polarization of a BSBT film is enhanced due to the lattice extension derived from A–O* dipole regulation, which brings about improved energy storage performances with the density reaching as high as 102.9 J cm−3 and the efficiency increasing to 64.8%. This work provides a preferred alternative strategy to regulate the relaxor behavior by domain reconstruction for dielectric energy storage.