论文标题
极性不连续性的铁电钙钛矿超晶格的压电特性
Piezoelectric properties of ferroelectric perovskite superlattices with polar discontinuity
论文作者
论文摘要
从密度功能功能理论中的第一个原理中研究了高对称性$ p4mm $ pall pall阶段的稳定性。结果表明，在大多数超级晶格中，此阶段表现出铁电的不稳定性或抗铁病症或两者。对于每个超晶格，计算地下结构，可能的亚稳相结构，自发极化和压电特性。将超极性不连续性的超晶格的性质与具有破碎的对称性和普通超级晶格的超级晶格的特性进行了比较，而这些超晶格没有极性不连续性。结果表明，在某些超极性不连续性的某些超晶格中，高的压电系数（高达150--270 pc/n）是由于外部应变的影响，其对称性遵循强烈的晶格扭曲的出现，其对称性遵循地下态结构的低ly裂极性声子模式。
The stability of a high-symmetry $P4mm$ polar phase in seventeen short-period ferroelectric perovskite superlattices with polar discontinuity is studied from first principles within the density-functional theory. It is shown that in most superlattices this phase exhibits either the ferroelectric instability or the antiferrodistortive one, or both of them. For each superlattice, the ground-state structure, the structure of possible metastable phases, the spontaneous polarization, and piezoelectric properties are calculated. The properties of superlattices with the polar discontinuity are compared with those of superlattices with broken symmetry and of ordinary superlattices, which have no the polar discontinuity. It is shown that high piezoelectric coefficients (up to 150--270 pC/N) in some superlattices with the polar discontinuity are due to the appearance of strong lattice distortions, whose symmetry follows that of a low-lying polar phonon mode of the ground-state structure, under the influence of external strain.
