Highly charged 180 degree head-to-head domain walls in lead titanate
Highly charged 180 degree head-to-head domain walls in lead titanate
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DOI：
10.1038/s42005-020-00488-x
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发表时间：
2020-12-15
影响因子：
5.5
通讯作者：
Bangert, Ursel
中科院分区：
文献类型：
--
作者：
Moore, Kalani;Conroy, Michele;Bangert, Ursel
铁电材料中的带电畴壁是一个研究热点。微尺度应变被认为是一种诱导双壁阵列以直角相遇的方法，形成具有新材料特性的针尖畴。原子尺度的特征表现出这些令人兴奋的行为是无法访问的piezoresponse力显微镜分辨率以前的工作。在这里，我们使用像差校正的扫描透射电子显微镜观察短，阶梯状，高度带电的DWs在铁电PbTiO 3的针尖。反向Ti 4+位移极化映射证实了相邻域中的头对头极化。应变映射揭示了大的偏差，从散装和更广泛的DW与高Pb2+空位浓度。额外的屏蔽电荷被发现，以稳定DW垂直于相反的极化矢量，从而构成最高度带电DW可能在PbTiO 3。针尖结处的这一特征是贯穿样品的5 nm x 2 nm通道，并且可能具有有用的导电性质。我们设想类似的结可以在其他铁弹性材料中形成，并产生令人兴奋的现象，为未来的研究。畴壁是铁性系统的基本组成部分，并决定了整体铁性。在这里，作者使用像差校正的扫描透射电子显微镜观察铁电PbTiO 3中带电针点畴壁的形成及其特性如何取决于铅空位浓度。
Charged domain walls (DWs) in ferroelectric materials are an area of intense research. Microscale strain has been identified as a method of inducing arrays of twin walls to meet at right angles, forming needlepoint domains which exhibit novel material properties. Atomic scale characterisation of the features exhibiting these exciting behaviours was inaccessible with the piezoresponse force microscopy resolution of previous work. Here we use aberration corrected scanning transmission electron microscopy to observe short, stepped, highly charged DWs at the tip of the needle points in ferroelectric PbTiO3. Reverse Ti4+ shift polarisation mapping confirms the head-to-head polarisation in adjacent domains. Strain mapping reveals large deviations from the bulk and a wider DW with a high Pb2+ vacancy concentration. The extra screening charge is found to stabilise the DW perpendicular to the opposing polarisation vectors and thus constitutes the most highly charged DW possible in PbTiO3. This feature at the needle point junction is a 5 nm x 2 nm channel running through the sample and is likely to have useful conducting properties. We envisage that similar junctions can be formed in other ferroelastic materials and yield exciting phenomena for future research.Domain walls are the basic building blocks of a ferroic system and determine the overall ferroic properties. Here, the authors use aberration corrected scanning transmission electron microscopy to observe the formation of charged needle point domain walls in ferroelectric PbTiO3 and how their characteristics depend on the lead vacancy concentration.