纳米铁电材料铁电性及其力电耦合特性的原子尺度模拟研究

doi:10.15541/jim20140492

摘要/Abstract

摘要：

纳米铁电材料的几何构型和特征尺寸严重影响着材料的铁电性, 对微电子器件中功能材料的可靠性有着至关重要的影响。数值模拟是研究铁电材料物理特性的重要手段, 并且当材料的特征尺寸缩小至数个纳米的量级时, 由于极小试样精密制备和微小物理量准确测量等方面困难的制约, 数值模拟可能是唯一有效的办法。本文综述了典型二维、一维及零维纳米铁电材料铁电性的若干数值模拟研究进展, 重点介绍了纳米铁电材料的极化分布、铁电相变、铁电临界尺寸和力电耦合特性等关键问题的研究成果, 展望了纳米铁电材料模拟研究方面的研究重点。

关键词: 纳米铁电材料, 铁电极化, 铁电临界尺寸, 力电耦合, 数值模拟, 综述

Abstract:

For nanoscale ferroelectric materials, their geometrical structures and characteristic sizes strongly affect the ferroelectricity, which are dominant factors for the reliability of functional materials in micro-electronics. Numerical simulation is an effective tool instead of the experimental method to investigate the physical properties of ferroelectrics. Particularly, when the characteristic sizes of these materials shrink to several nanometers, it may be the only option because no experimental testing system is available due to the restriction in specimen fabrication and measurement precision. In this paper, recent progresses in numerical simulations on the ferroelectricity of typical 2D, 1D and 0D nano-ferroelectrics are reviewed, especially researches on the polarization distribution, phase transition, critical size, and electromechanical coupling behavior of nanoscale ferroelectrics. Finally, the potential research emphases on numerical simulation of the nanoscale ferroelectrics are prospected.

Key words: nanoscale ferroelectrics, polarization, critical size of ferroelectricity, electromechanical coupling behavior, numerical simulation, review

中图分类号:

TM22

王晓媛, 闫亚宾, 嶋田隆広, 北村隆行. 纳米铁电材料铁电性及其力电耦合特性的原子尺度模拟研究[J]. 无机材料学报, 2015, 30(6): 561-570.

WANG Xiao-Yuan, YAN Ya-Bin, SHIMADA Takahiro, KITAMURA Takayuki. Research Progress in Atomistic Simulation on Ferroelectricity and Electromechanical Coupling Behavior of Nanoscale Ferroelectrics[J]. Journal of Inorganic Materials, 2015, 30(6): 561-570.

图/表 8

图1 (a)顺电相和(b)铁电相时钙钛矿材料ABO3的晶体结构

Fig. 1 Crystal structures of perovskite oxides ABO3 in the (a) paraelectric phase and (b) ferroelectric phase

图2 顺电态、铁电态和反铁电畸变态时钙钛矿材料ABO3的原子位移示意图

Fig. 2 Atomic structure of ABO3 in the paraelectric, ferroelectric and antiferrodistortive phases

图3 发生c(2×2)表面重组时TiO2层原子结构示意图[45]

Fig. 3 Atomic structure of the TiO2 layer for the c(2×2) PbTiO3 surface reconstruction[45]

图4 (a)、(b)和(c)为发生c(2×2)表面重组时表面TiO2层和PbO层原子的AFD、AFE和FE位移图, (d)、(e)和(f)为极化方向示意图[48]

Fig.4 Atomic displacements in TiO2 and PbO planes, for the AFD, AFE and FE distortions of the c(2×2) surface reconstruction (a-c), and schematic representation of the polarization distortion parameters, respectively (d-f)[48]

图5 拉伸应变εzz作用下边缘处由(a)PbO表面层和(b)TiO2表面层构成的PbTiO3纳米线平均铁电极化P的变化趋势, 其中1×1、2×2和3×3代表纳米线横截面的大小[58]

Fig. 5 Averaged polarization, P, in (a) PbO-terminated and (b) TiO2-terminated nanowires with the cross-section of the 1×1、2×2 and 3×3 cells as a function of tensile strain, εzz[58]

图6 (a)4×4 TiO2表面纳米线面内电偶极子分布, (b)~ (f)4×4纳米线各原子的面内位移[66]

Fig. 6 (a) Dipole moments, and (b)-(f) in-plane displacements of individual atoms with respect to a paraelectric reference state for a 4×4 TiO2-terminated PbTiO3 nanowire[66]

图7 (a)二维涡旋极化分布和(b)三维涡旋极化分布示意图[83]

Fig. 7 (a) 2-D tetradomain vortex consisting of four domains, (b) 3-D hexadomain vortex[83]

图8 归一化自由能随纳米点结构长高比的变化趋势[83]

Fig. 8 Normalized free energy vs aspect ratio for cuboidal nanodots[83]

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