Enhanced hybrid improper ferroelectricity in Fe/Nb cosubstituted Ca3Mn2O7 ceramics
Enhanced hybrid improper ferroelectricity in Fe/Nb cosubstituted Ca3Mn2O7 ceramics
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Fe/Nb 共取代 Ca3Mn2O7 陶瓷中增强的杂化不当铁电性
DOI：
10.1111/jace.17791
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发表时间：
2021
影响因子：
3.9
通讯作者：
Chen Xiang Ming
中科院分区：
文献类型：
--
作者：
Chen Bu Hang;Sun Tu Lai;Wei Li Yu;Liu Xiao Qiang;Wen Wen;Tian He;Li Jiang Yu;Chen Xiang Ming
原型Ruddlesden-Popper化合物Ca 3 Mn 2 O 7被预测具有混合反常铁电性，其中极化由两个氧八面体畸变模式的凝聚引起。然而，这是一个很大的挑战，在室温下在Ca 3 Mn 2 O 7中的极化切换，因为中间非极化相的存在下，通常会导致复杂的域形态。本文报道了Fe/Nb共取代对Ca 3 Mn 2 O 7中混合反常铁电性的影响，并在室温下实现了Ca 3 [Mn0.5（Fe0.5Nb0.5）0.5] 2 O 7的易极化反转。在远高于室温的温度下，铁电相变直接从I4/mmm转变到A21 am，而没有中间的非极化相。不同的转变路径形成交替的180°型铁电畴，而不是沿着沿着[001]堆叠的不规则的90°型铁弹畴，导致在室温下容易的极化切换。此外，由于氧八面体畸变的幅度较大，A位Ca阳离子的反铁电畸变位移增加，从而获得增强的铁电极化（Pr~2.0 μC/cm ~ 2）。本文强调了化学压力对于相变、畴形态和铁电特性的可调谐性，它为设计和制造高性能反常铁电体提供了一种有用的方法。
The prototypical Ruddlesden‐Popper compound Ca3Mn2O7has been predicted to possess hybrid improper ferroelectricity, where the polarization is induced by the condensation of two oxygen octahedral distortion modes. Nevertheless, it is a big challenge to switch the polarization at room temperature in Ca3Mn2O7since the presence of intermediate nonpolarAcaaphase generally leads to the complex domain morphology. Here, the effects of Fe/Nb cosubstitution on hybrid improper ferroelectricity in Ca3Mn2O7are reported, and easy polarization switching at room temperature is achieved in Ca3[Mn0.5(Fe0.5Nb0.5)0.5]2O7. The ferroelectric phase transition occurs directly fromI4/mmmtoA21amat a temperature far above room temperature without intermediate nonpolarAcaaphase. The distinct transition pathway forms the alternating 180°‐type ferroelectric domains rather than the irregular 90°‐type ferroelastic domains stacked along [001], resulting in easy polarization switching at room temperature. Moreover the enhanced ferroelectric polarization (Pr~2.0 μC/cm2) is obtained due to the increased anti‐ferrodistortive displacements of Ca cations atA‐site, arising from the larger amplitudes of oxygen octahedral distortions. Chemical pressure is emphasized here for the tunability of phase transition, domain morphology, and ferroelectric characteristics, and it provides a useful approach for designing and creating high‐performance improper ferroelectrics.