Influence of misfit stresses on the dielectric permeability of ferroelectric superlattices BaTiO₃/BaZrO₃

Abstract

The mechanisms of increasing the dielectric response of the BaTiO 3 /BaZrO 3 ferroelectric superlattices in comparison with the characteristics of the bulk materials of the lattice are discussed. It is assumed that changes in the dielectric response in superlattices are caused by mechanical stresses arising in layers of the superlattice due to the mismatch of the sizes of the unit cells that make up the lattice of single-crystal layers. These stresses lead to the formation of longitudinal polarization in the layers of barium titanate and to the related contribution of the transverse component of the dielectric tensor to the effective permeability of the superlattice in the direction normal to the plane of the layers. The misfit stresses cause the appearance of a ferroelectric phase transition in the barium zirconate the lattice layers with an increase in the dielectric constant of these layers in the direction normal to the plane of the lattice layers. Highlights: Mismatch stresses in ferroelectric superlattices

Research Progress on Ferroelectric Superlattices

“…铁电薄膜具有比较高的介电常数，被广泛用于 制造薄膜电容器等电子元器件。电容与介电常数成 正比，提高介电常数有利于器件的小型化。对于铁 电超晶格，利用 Maxwell-Wagner 效应 [63] 、应变效 应 [47,64] 、以及调控界面缺陷分布 [9,[65][66] 和电畴形态 [67] 可以显著地提高其介电性能。Bousquet 等 [13]…”

“…BaTiO3/SrTiO3 超晶格的介电常数高达 900，远大于 (Ba0.5Sr0.5)TiO3 固 溶 体 薄 膜 [32] 。在 Ba-TiO3/Pb(Zr0.52Ti0.48)O3 铁电超晶格中 [9] ，聚集在 Ba-TiO3/Pb(Zr0.52Ti0.48)O3 界面的空间电荷降低了其对 于畴壁运动的钉扎，使超晶格的介电常数远大于在 相同条件下制备的纯 BaTiO3 和 Pb(Zr0.52Ti0.48)O3 薄 膜。Chen 等 [65] 在 BaTiO3/NiO 铁电超晶格内也观察 到了类似的现象，并且认为 Maxwell-Wagner 效应 和界面聚集的空间电荷是介电性能增加的主要原因。 大量的研究结果表明，铁电超晶格的介电性能与周 期厚度密切相关 [32,35,47,64,[67][68] ，通过减小周期厚度， 增强界面效应的作用，可以显著地提高超晶格的介 电常数。…”