Domain Wall Displacement is the Origin of Superior Permittivity and Piezoelectricity in BaTiO 3 at Intermediate Grain Sizes
Domain Wall Displacement is the Origin of Superior Permittivity and Piezoelectricity in BaTiO 3 at Intermediate Grain Sizes
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DOI：
10.1002/adfm.201301913
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发表时间：
2014-02-01
影响因子：
19
通讯作者：
Jones, Jacob L.
中科院分区：
文献类型：
--
作者：
Ghosh, Dipankar;Sakata, Akito;Jones, Jacob L.
铁电多晶材料的介电和压电性能一直被认为是晶粒尺寸和畴壁运动等外在效应的强烈函数。例如，在BaTiO3中，几十年来已经观察到压电和介电性能在中等晶粒尺寸（约1 m）时达到最大，并且已经引入了不同的理论模型来描述这种效应的物理起源。在此，在电场作用过程中使用原位高能x射线衍射，表明在这些中间晶粒尺寸下，在强（高于矫顽力）和弱（低于矫顽力）电场下，90度畴壁运动最大，这与在BaTiO3中观察到的增强的介电常数和压电性能有关。这一结果验证了长期以来将多晶BaTiO3的尺寸效应归因于畴壁位移的理论。目前已有经验证明，通过畴壁位移效应可以使多晶铁电材料的压电和介电性能提高一倍以上；这些机制被建议用于设计具有增强性能的新型铁电材料。
The dielectric and piezoelectric properties of ferroelectric polycrystalline materials have long been known to be strong functions of grain size and extrinsic effects such as domain wall motion. In BaTiO3, for example, it has been observed for several decades that the piezoelectric and dielectric properties are maximized at intermediate grain sizes (approximate to 1 m) and different theoretical models have been introduced to describe the physical origin of this effect. Here, using in situ, high-energy X-ray diffraction during application of electric fields, it is shown that 90 degrees domain wall motion during both strong (above coercive) and weak (below coercive) electric fields is greatest at these intermediate grain sizes, correlating with the enhanced permittivity and piezoelectric properties observed in BaTiO3. This result validates the long-standing theory in attributing the size effects in polycrystalline BaTiO3 to domain wall displacement. It is now empirically established that a doubling or more in the piezoelectric and dielectric properties of polycrystalline ferroelectric materials can be achieved through domain wall displacement effects; such mechanisms are suggested for use in the design of new ferroelectric materials with enhanced properties.