基于压电模式原子力显微技术的铁电材料纳米尺度非线性动力学研究

Tunable ferroelectric domains at the nanoscale underpins the future broad applications of ferroelectrics in information storage areas. Recently, piezoresponse force microscopy has rapidly developed as one of the powerful tools on the characterization and investigation of various polar materials and systems in the nanoscale, particularly on the nucleation and switching of ferroelectric domains, and harvest findings have been achieved. Although the basic principle of piezoresponse force microscopy is straightforward, it is still limited to distinguish the deformation of ferroelectrics induced by a variety of micro-mechanisms, including spontaneous polarization, charges, and ionics. The complex interactions among them, further lead to the great difficulty on investigating the nonlinear dynamics of ferroelectric domains. Based on the confusions and difficulties, in this project, we will devote to resolve the micro-mechanisms of the deformation induced by the spontaneous polarization and ionics in ferroelectrics, and further move to study their interactions. The ultimate goal of this project is to analyze the nonlinear dynamics of ferroelectric domains with consideration of surface charges and ionics. Our works should provide the significant guidance for nanoscale process and manufacture of ferroelectrics, laid foundations for the design, fabrication, and optimization of the nanoscale ferroelectric devices.

铁电材料因内部电畴能够在纳米尺度实现可控性翻转而在信息存储等领域具有广泛的应用前景。近年提出的压电模式原子力显微技术，已经快速发展成为在纳米尺度表征和研究各类极性材料体系的重要工具，特别是在电畴形核和翻转动力学方面取得了丰硕的成果。虽然其工作原理非常直观，然而材料内引起铁电材料发生形变的微观机制却非常复杂，目前实验上仍然无法准确区分不同微观机制下的应变响应。这些微观机制包括自发极化、电荷和离子，而它们间又存在复杂交互作用，这使得铁电畴非线性动力学分析变得尤为困难。基于此，本项目将针对压电模式原子力显微技术在响应机理和铁电畴动力学方面的困难，建立力-电-化学多场耦合模型，分析不同微观机制下位移响应的微观机理，探究极化、电荷与离子间复杂交互作用，实现铁电材料纳米尺度的非线性动力学分析。这为铁电材料纳米加工和制造提供了重要指导，最终为纳米器件的设计、制造和优化奠定基础。

铁电材料作为一类重要的功能材料在信息领域中极富应用前景，主要是因为其优异的力电耦合性能和可控的微观电畴结构。压电模式原子力显微技术(PFM)已经广泛用于在纳米尺度表征铁电材料局域力电耦合性能和微观结构，然而引起铁电材料发生形变的微观机制却非常复杂，目前实验上仍然无法准确区分不同微观机制下的应变响应。本项目基于导电扫描探针激发的局域的非均匀电场，发展了力-电-化学多场耦合力学方法、非传统的相场方法、接触模式力电全耦合力学理论，用于分析离子导体中的离子输运特性，探究铁电材料中电畴结构的演化，并提出了分辨不同机理下的压电模式原子力显微技术信号响应的新方法。相关成果发表在Journal of the Mechanics and Physics of Solids, International Journal of Mechanical Sciences, npj Computational Materials, Journal of Applied Physics等国际国内知名期刊上，为复杂耦合机理下纳米尺度力电耦合响应定量分析提供重要指导。