论文标题
dion-jacobson分层perovskites csndnb $ _2 $ o $ $ _7 $和rbndnb $ _2 $ o $ $ _7 $
Ferroelectricity of Dion-Jacobson layered perovskites CsNdNb$_2$O$_7$ and RbNdNb$_2$O$_7$
论文作者
论文摘要
Dion-Jacobson中的晶体学和电介质特性分层的钙钛矿，CSNDNB $ _2 $ o $ _7 $和rbndnb $ _2 $ o $ _7 $，已在密集的多晶体样品中进行了检查，并且极化的近极化渗透率是室内的室温，已经在室内体验了室温。这两个阶段在两种类型的非极性八面体旋转的组合引起的自发极化的理论机制是，“混合不当的铁电机制”，通过两种类型的非极性八面体旋转。到目前为止，Ferroectricity在CSNDNB中的介电常数$ _2 $ o $ _7 $在625 K处表现出对应于铁电的异常，如X射线和中子衍射量，以前揭示了$ __2 $ __2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2。 773 k），这与以前的衍射法一致，显示了极性$ i2cm $对称的持久性，最高为790 k。
Crystallography and dielectric properties in Dion-Jacobson layered perovskites, CsNdNb$_2$O$_7$ and RbNdNb$_2$O$_7$, have been examined in dense polycrystalline samples, and polarization hysteresis loops that substantiate ferroelectricity have been observed at room temperature. The theoretical mechanism for the spontaneous polarization, "hybrid improper ferroelectric mechanism,'' induced by a combination of two types of non-polar octahedral rotations, is confirmed in these two phases. Our samples show remanent polarizations of 2-3 $μ$C/cm$^2$, which are much larger than those obtained in polycrystalline samples with the hybrid improper ferroelectricity reported so far. A dielectric constant in CsNdNb$_2$O$_7$ exhibits an anomaly at 625 K, corresponding to the ferroelectric transition, as previously revealed by x-ray and neutron diffractometry. No dielectric anomaly is observed for RbNdNb$_2$O$_7$ throughout the temperature range studied here ($\leq$ 773 K), which is consistent with the previous diffractometry showing the persistence of polar $I2cm$ symmetry up to 790 K.
