论文标题
稳定的极性氧气通过外延菌株
Stable Polar Oxynitrides through Epitaxial Strain
论文作者
论文摘要
我们通过基于群 - 智能的结构预测方法，DFT晶格动力学和第一原则分子动力学来研究ABO $ _2 $ n oxyntrides的能量有利的结构。我们预测在高压下的几种热力学稳定的极性氧气钙钛矿。此外，我们发现钙钛矿结构的氧硝酸盐的铁电性相位可以在适当的底物上在高压下在高压下合成。在环境压力下外延应变下铁电氧的动力稳定性也意味着有可能使用脉冲激光沉积或其他原子层沉积方法合成它们。我们的结果对进一步探索其他氧气含量也具有广泛的影响。我们进行了第一原理分子动力学，发现Ysio $ _2 $ n的极性钙钛矿在压缩外延菌株下至少至至少600 K，然后再转换为稳定的Wollastonite-like-like-like结构。 YSIO $ _2 $ N在压力下以延伸的外延应变稳定。我们预测Lasi $ _2 $ n，Lageo $ _2 $ N，BISIO $ _2 $ N和BIGEO $ _2 $ N即使没有外部压力，也可以在零压力下作为零压力的Ferroelectric Perovskites进行中稳定。
We investigate energetically favorable structures of ABO$_2$N oxynitrides as functions of pressure and strain via swarm-intelligence-based structure prediction methods, DFT lattice dynamics and first-principles molecular dynamics. We predict several thermodynamically stable polar oxynitride perovskites under high pressures. In addition, we find that ferroelectric polar phases of perovskite-structured oxynitrides can be thermodynamically stable and synthesized at high pressure on appropriate substrates. The dynamical stability of the ferroelectric oxynitrides under epitaxial strain at ambient pressure also imply the possibility to synthesize them using pulsed laser deposition or other atomic layer deposition methods. Our results have broad implications for further exploration of other oxynitride materials as well. We performed first-principles molecular dynamics and find that the polar perovskite of YSiO$_2$N is metastable up to at least 600 K under compressive epitaxial strain before converting to the stable wollastonite-like structures. YSiO$_2$N is stabilized under pressure with extensional epitaxial strain. We predict that LaSi$_2$N, LaGeO$_2$N, BiSiO$_2$N, and BiGeO$_2$N are metastable as ferroelectric perovskites at zero pressure even without epitaxial strain.
