铁电性
居里温度
材料科学
超晶格
电介质
凝聚态物理
钙钛矿(结构)
兴奋剂
相变
布里渊区
晶格常数
衍射
分析化学(期刊)
结晶学
化学
光学
物理
铁磁性
光电子学
色谱法
作者
Lintao Liu,Tao Chen,Di Ouyang,Yumei Yue,Bin Yang,Haixue Yan,Isaac Abrahams,Zhengqian Fu,Ruihong Liang,Zhiyong Zhou
摘要
Abstract The spontaneous polarization of perovskite layer structured Sr 2 Nb 2 O 7 ferroelectrics (FEs) is originated from mainly the oxygen octahedral rotations and partially the displacement of Sr 2+ ions. However, there is FE anomaly of showing the typical characteristics of antiferroelectric (AFE)‐like behavior with double polarization–electric field hysteresis loops of Sr 2 Nb 2 O 7 ceramics by Pb doping. Here, combinations of low frequency and sub‐terahertz band dielectric measurements under applied DC field reveal field‐induced transition from AFE to FE structure. Temperature dependence of dielectric constant suggested a second‐order phase transition near 215°C, which further supported by the lattice parameters and thermal expansion coefficient extracted from the variable temperature X‐ray diffraction in the heating and cooling processes. The selected area electron diffraction results show no new superlattice spots are observed along [1 0 0] zone axis related to c direction. We proposed a model based on octahedral tilting/rotation that accounted for the incommensurate lattice modulation in the c direction for Sr 2 Nb 2 O 7 system by Pb doping. All the results show AFE‐like behavior be likely to origin from the electron structures of Pb 2+ with a 6 s 2 lone pair. Our results gave us a new concept provide possibilities for the design of AFE‐like materials in layer structured compounds with super high FE Curie point.
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