纳米线电卡效应的表面应力与固溶改性相场模拟  

Simulation of surface stress and solid solution modification phase field of nanowire electrocaloric effect

作　　者：邹幸 朱哲 方文啸[2] Zou Xing;Zhu Zhe;Fang Wen-Xiao(School of Materials Science and Engineering,Xiangtan University,Xiangtan 411100,China;School of Integrated Circuit,Sun Yat-sen University,Shenzhen 518107,China)

机构地区：[1]湘潭大学材料科学与工程学院,湘潭411100 [2]中山大学集成电路学院,深圳518107

出　　处：《物理学报》2024年第10期50-58,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:92166111);湖南省教育厅重点项目(批准号:21A0121)资助的课题。

摘　　要：以铁电纳米线为填料的复合薄膜表现出了满足固态制冷需求的高绝热温变,其平行分布填充的纳米线因和传统垂直分布的取向不同,被认为是获得大电卡效应的关键因素,然而其大电卡效应的内在机理尚不十分明确.因此本文以PbTiO_(3)纳米线为研究对象,建立平行分布纳米线模型,通过相场模拟研究表面应力和固溶改性对其电卡效应的影响.结果表明,表面应力和固溶改性能够分别调控纳米线相变温度并获取大的绝热温变,并最终实现了在600 kV/cm电场下,0-300℃的宽温度区间获得大于6 K绝热温变的效果.同时结合三维畴结构的演变,揭示了诱发不同畴翻转类型是平行分布纳米线结构获得大电卡效应的内在机理.通过本研究为基于平行分布铁电纳米线电卡效应的固态制冷技术发展提供了有益的理论指导.Composite films with ferroelectric nanowires serving as fillers,exhibit high adiabatic temperature change to meet the requirement for solid-state refrigeration,and their parallel-distributed filled nanowires are considered to be the key factor because their orientation is different from the orientation of the conventional perpendicularly distributed filled nanowires.However,the underlying mechanism of the electrocaloric effect of parallel-distributed nanowires has not been well understood.In this paper,a parallel-distributed PbTiO_(3) nanowire model is established to investigate the effects of surface stress and solid solution modification on their electrocaloric effects through phase field simulations.The results show that an adiabatic temperature change of 5 K can be obtained near 200℃ with 1.5%compressive stress under an electric field of 260 kV/cm.In order to further reduce its operating temperature,the electrocaloric effects of PST nanowires with different Sr contents are calculated,and it is found that the lower the doping amount of Sr,the higher the phase transition temperature of PST nanowires is.When the doping amount of Sr is 0.45,the phase transition temperature of the nanowires can be reduced to near 100℃,and an adiabatic temperature change of more than 8 K can be obtained under an electric field of 600 kV/cm.Even in the low-temperature interval from 50 to 100℃the nanowires exhibit an adiabatic temperature change close to 8 K.The nanowires are also characterized by an adiabatic temperature change in a low-temperature interval from 50 to 100℃.At the same time,by combining the evolution of the simulated three-dimensional domain structure,it is revealed that the underlying mechanism of the change of the electrocaloric effect under surface stress and solid solution modification is due to different types of domain transformations.Finally,the combinations of components and surface stresses corresponding to the maximum value of the electrocaloric effect at different operating temperatures are discuss

关 键 词：电卡效应 纳米线 表面应力 固溶改性 

分 类 号：O469[理学—凝聚态物理] TB383.1[理学—电子物理学]