Effect of geometric configuration on the electrocaloric properties of nanoscale ferroelectric materials
Effect of geometric configuration on the electrocaloric properties of nanoscale ferroelectric materials
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DOI：
10.1063/1.5020584
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发表时间：
2018-03-28
影响因子：
3.2
通讯作者：
Wang, Jie
中科院分区：
文献类型：
--
作者：
Hou, Xu;Li, Huiyu;Wang, Jie
铁电体的电热性能与材料中的电畴结构密切相关。对于纳米铁电材料，系统的几何构型对电畴结构有很大的影响。采用基于Ginzburg-Landau理论的实空间相场模型，研究了纳米铁电材料的几何构型对电热性能的影响。对正方形、蜂窝状和三角形阿基米德几何构型的铁电纳米材料在不同温度下的电滞回线进行了模拟。利用基于电滞回线的麦克斯韦关系计算了三种铁电纳米材料在不同电场作用下的绝热温变。结果表明，在3种几何构型中，蜂窝状试样在391.8kV/cm电场下的ATC最大，为Δ T = 4.3 ℃，而正方形试样在相同电场下的ATC最小，为Δ T = 2.7 ℃。三种几何构型的不同电热特性源于不同的畴结构。正方形试样中垂直于电场方向的自由面比其他两个试样多，这限制了更多的垂直于电场方向的极化，导致较小的ATC。由于蜂窝状试样中没有垂直于电场的自由表面，在电场方向上极化随温度的变化更容易，从而导致大的ATC。本工作提出了一种新的方法来获得可调的电热性能的纳米铁电材料，通过设计其几何构型。出版社：AIP Publishing
The electrocaloric properties of ferroelectrics are highly dependent on the domain structure in the materials. For nanoscale ferroelectric materials, the domain structure is greatly influenced by the geometric configuration of the system. Using a real-space phase field model based on the GinzburgLandau theory, we investigate the effect of geometric configurations on the electrocaloric properties of nanoscale ferroelectric materials. The ferroelectric hysteresis loops under different temperatures are simulated for the ferroelectric nano-metamaterials with square, honeycomb, and triangular Archimedean geometric configurations. The adiabatic temperature changes (ATCs) for three ferroelectric nano-metamaterials under different electric fields are calculated from the Maxwell relationship based on the hysteresis loops. It is found that the honeycomb specimen exhibits the largest ATC of Delta T = 4.3 degrees C under a field of 391.8 kV/cm among three geometric configurations, whereas the square specimen has the smallest ATC of Delta T = 2.7 degrees C under the same electric field. The different electrocaloric properties for three geometric configurations stem from the different domain structures. There are more free surfaces perpendicular to the electric field in the square specimen than the other two specimens, which restrict more polarizations perpendicular to the electric field, resulting in a small ATC. Due to the absence of free surfaces perpendicular to the electric field in the honeycomb specimen, the change of polarization with temperature in the direction of the electric field is more easy and thus leads to a large ATC. The present work suggests a novel approach to obtain the tunable electrocaloric properties in nanoscale ferroelectric materials by designing their geometric configurations. Published by AIP Publishing.