Abstract The stability of a high-symmetry P 4 mm 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.

中文翻译：

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具有极性不连续性的铁电钙钛矿超晶格的压电特性

摘要 从密度泛函理论中的第一性原理出发，研究了 17 个具有极性不连续性的短周期铁电钙钛矿超晶格中高对称性 P 4 mm 极性相的稳定性。结果表明，在大多数超晶格中，该相表现出铁电不稳定性或反铁畸变，或两者兼而有之。对于每个超晶格，计算基态结构、可能的亚稳态结构、自发极化和压电特性。将具有极不连续性的超晶格的性质与具有破缺对称性的超晶格和没有极不连续性的普通超晶格的性质进行比较。