The bismuth-based perovskites are an interesting class of materials that exhibit a variety of coupled ferroic properties. Through epitaxial growth in the (001) pseudo-cubic [(001)pc] orientation, various phases with variable ferroelectric polarization can be stabilized. Using density-functional theory calculations, we predict the phase stability of the bismuth-based perovskite oxides as a function of pseudo-cubic in-plane (IP) lattice constant, mimicking (001)pc epitaxial films. We find that the BiMnO3, BiCoO3, and BiNiO3 systems each exhibit only one stable phase over a wide range of IP lattice constants. In the BiFeO3 (BFO) and BiCrO3 (BCO) systems, by comparison, we find several phases that are energetically favorable, depending on the value of the IP strain. The BFO phases predicted to be stable, in order of increasing compressive IP strain, are monoclinic Cc, triclinic P1, monoclinic Cm, and tetragonal P4mm. In the BCO system, we find two orthorhombic Pbnm phases, respectively, under no IP strain and under compressive IP strain, and one monoclinic Cc phase to be stable under tensile IP strain. Our results serve to guide experimental efforts in terms of selecting growth substrates with the goal of achieving desired epitaxial-stabilized perovskite phases and to support future investigations of the tunability of BXO properties with epitaxial strain.

中文翻译：

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基于密度泛函理论的外延 BiXO3 相稳定性

铋基钙钛矿是一类有趣的材料，具有多种耦合铁性。通过（001）伪立方[（001）pc]取向的外延生长，可以稳定具有可变铁电极化的各种相。使用密度泛函理论计算，我们预测铋基钙钛矿氧化物的相稳定性作为伪立方面内 (IP) 晶格常数的函数，模拟 (001) pc 外延膜。我们发现 BiMnO3、BiCoO3 和 BiNiO3 系统在很宽的 IP 晶格常数范围内都只表现出一种稳定相。相比之下，在 BiFeO3 (BFO) 和 BiCrO3 (BCO) 系统中，我们发现了几个在能量上有利的相，这取决于 IP 应变的值。BFO 相预测为稳定，按 IP 压缩应变增加的顺序，是单斜 Cc、三斜 P1、单斜 Cm 和四方 P4mm。在 BCO 系统中，我们发现两个正交 Pbnm 相分别在无 IP 应变和压缩 IP 应变下，以及一个单斜 Cc 相在 IP 拉伸应变下稳定。我们的结果有助于在选择生长衬底方面指导实验工作，以实现所需的外延稳定钙钛矿相，并支持未来对 BXO 特性与外延应变的可调性的研究。