Ferrielectric-mediated morphotropic phase boundaries in Bi-based polar perovskites
Ferrielectric-mediated morphotropic phase boundaries in Bi-based polar perovskites
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DOI：
10.1038/s41598-019-40724-1
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发表时间：
2019-03-11
影响因子：
4.6
通讯作者：
Noguchi, Yuji
中科院分区：
文献类型：
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作者：
Kitanaka, Yuuki;Miyayama, Masaru;Noguchi, Yuji
铁电体的自发极化（P-s）为传感器、致动器和诊断成像传感器等压电器件的发展提供了动力。广泛使用的铅基钙钛矿表现出一个成分驱动的相图，涉及一个过渡区域，称为形态取向相边界，其中铁电结构变化剧烈，压电活性最大。在某些钙钛矿中，铁极化与八面体的非极性旋转共存，显示出前所未有的相图。在这里，我们展示了在bi1 / 2na1 / 2tio3基钙钛矿中，“铁电体”作为铁电体之间具有菱形和四方对称的桥接相出现。中子衍射分析表明，中间铁电体表现出较小的P-s，这是由上下极化加上同相TiO6旋转引起的。我们的从头计算表明，在适当的化学压力下，交错的Bi-O构象提供了铁电介导的相边界，这为具有增强物理性能的（多）铁材料提供了一个有前途的平台。
Spontaneous polarization (P-s) in ferroelectrics has provided the impetus to develop piezoelectric devices such as sensors, actuators and diagnostic imaging transducers. Widely used lead-based perovskites exhibit a composition-driven phase diagram involving a transition region, known as a morphotropic phase boundary, where the ferroelectric structure changes dramatically and the piezoelectric activity is maximal. In some perovskites, ferroic polarization coexists with nonpolar rotations of octahedra, suggesting an unprecedented phase diagram. Here, we show morphotropic phase boundaries, where 'ferrielectric' appears as a bridging phase between ferroelectrics with rhombohedral and tetragonal symmetries in Bi1/2Na1/2TiO3-based perovskites. Neutron diffraction analysis demonstrates that the intermediate ferrielectric displays a small P-s resulting from up and down polarizations coupled with an in-phase TiO6 rotation. Our ab initio calculations indicate that a staggered Bi-O conformation at an appropriate chemical pressure delivers the ferrielectric-mediated phase boundaries, which provides a promising platform for (multi) ferroic materials with enhanced physical properties.