Domain- and symmetry-transition origins of reduced nanosecond piezoelectricity in ferroelectric/dielectric superlattices
Domain- and symmetry-transition origins of reduced nanosecond piezoelectricity in ferroelectric/dielectric superlattices
复制标题
铁电/介电超晶格中纳秒压电性降低的畴和对称性跃迁起源
DOI：
10.1088/1367-2630/14/1/013034
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
P. Evans
中科院分区：
文献类型：
--
作者：
Pice Chen;J. Jo;Ho Nyung Lee;E. Dufresne;S. Nakhmanson;P. Evans
具有原子尺度周期性的复合氧化物超晶格(SLS)具有不同于均匀组成的薄膜的动力学性质。这些性质的起源与极化域的动力学和场驱动的对称性变化密切相关，这些对称性是由不同组分之间的界面耦合引起的。在使用时间分辨X射线显微衍射探测铁电/电介质BaTiO(BTO)/CaTiO(CTO)SL的压电性的实验中，这些动力学在从几纳秒到几毫秒的时间尺度上是显而易见的。在100 ns的时间尺度上，压电变形大约是毫秒范围内的十分之一。在以前研究的PbTiO_3/SrTiO_3 SLS或成分均匀的铁电材料中，如PbTiO_3/SrTiO_3的四方组成的Pb(Zr，Ti)O_3，在短时间内没有观察到这种降低的压电性。BTO/CTO SL的异常行为可以与纳米域态向均匀偏振态的转变或场诱导的晶体对称性转变有关。与其他组成不同的复合氧化物中这两种动力学现象的特征时间尺度的比较表明，相变是一种更可能的可能性。
Complex-oxide superlattices (SLs) with atomic-scale periodicity have dynamical properties that are distinct from thin films of uniform composition. The origins of these properties are closely related to the dynamics of polarization domains and to field-driven changes in the symmetries resulting from interfacial coupling between different components. These dynamics are apparent at timescales from a few nanoseconds to several milliseconds in experiments probing the piezoelectricity of a ferroelectric/dielectric BaTiO3(BTO)/CaTiO3 (CTO) SL using time-resolved x-ray microdiffraction. At the 100 ns timescale, the piezoelectric distortion is approximately ten times smaller than in the millisecond regime. This reduced piezoelectricity at short timescales is not observed in previously studied PbTiO3/SrTiO3 SLs or compositionally uniform ferroelectrics such as tetragonal compositions of Pb(Zr,Ti)O3. The unusual behavior of the BTO/CTO SL can be linked to the switching of a nanodomain state into a uniform polarization state or to a field-induced crystallographic symmetry transition. A comparison of the results with the characteristic timescales of these two dynamical phenomena in other complex oxides with different compositions suggests that the phase transition is a more likely possibility.