论文标题
原子量表对称性和极性纳米簇在铁电材料的副阶段
Atomic scale symmetry and polar nanoclusters in the paraelectric phase of ferroelectric materials
论文作者
论文摘要
自从氧化物钙钛矿中发现铁电性以来，铁电材料名义上非极性副阶段的“禁止”局部和远程极性的性质一直是一个公开的问题（ABO3）。当前考虑的模型表明，B位原子沿<111>立方方向的局部相关的位移。这种异地位移已通过实验证实，但是，本质上是动态的，它们无法解释宏观实验所隐含的对称性孔偏振的静态性质。在这里，在通过纠正的扫描透射电子显微镜（STEM）通过拉曼光谱辅助的原子解决研究中，我们揭示，直接形象化和定量描述静态，2-4 nm大的极性纳米群，在名义上非极性立方体的（BA，SR）Tio3和Batio3和Batio3和Batio3。这些结果对理解无序材料的原子尺度结构，铁电的原始状态的起源，并且可能有助于回答有关纳米大小簇的动态静态性质的歧义。
The nature of the "forbidden" local- and long-range polar order in nominally nonpolar paraelectric phases of ferroelectric materials has been an open question since the discovery of ferroelectricity in oxide perovskites (ABO3). A currently considered model suggests locally correlated displacements of B-site atoms along a subset of <111> cubic directions. Such offsite displacements have been confirmed experimentally, however, being essentially dynamic in nature they cannot account for the static nature of the symmetry-forbidden polarization implied by the macroscopic experiments. Here, in an atomically resolved study by aberration corrected scanning transmission electron microscopy (STEM) complemented by Raman spectroscopy, we reveal, directly visualize and quantitatively describe static, 2-4 nm large polar nanoclusters in the nominally nonpolar cubic phases of (Ba,Sr)TiO3 and BaTiO3. These results have implications on understanding of the atomic-scale structure of disordered materials, the origin of precursor states in ferroelectrics, and may help answering ambiguities on the dynamic-versus-static nature of nano-sized clusters.
