铁电薄膜中力-挠曲电-化学耦合行为及其守恒积分

Ferroelectric thin film materials are widely used in sensors, ferroelectric memories and other intelligent devices. The performance of ferroelectric thin film determines the intellectualization and multi functions of these devices. The working environment of ferroelectric thin film is complex, and it is easy to be affected by the coupling of fields, such as temperature field, electric field and chemical process. At present, most researches only involve unidirectional or partial coupling, especially ignore the interaction between chemical diffusion process and other fields. Based on this, the irreversible mechano-flexoelectro-chemical diffusion fully coupling theory concerning the flexoelectric effect, surface effect and chemical diffusion process will be developed by combining the Landau - Ginzburg - Devonshire theory and the theory of non-equilibrium thermodynamics in this project. The evolving equations and the flexoelectro-chemical coupling constitutive equations will be established. The effects of flexoelectric coefficients, applied electric field and film thickness on ferroelectric properties of ferroelectric thin films will be investigated. Aiming at the problem that ferroelectric thin films are liable to fracture, this project intends to apply Noether theorem to the mechano-flexoelectro-chemical diffusion coupling process in ferroelectric thin films, and obtain the corresponding conservation integral. A numerical algorithm will be developed to calculate the conservation integral and the corresponding energy release rate will be obtained. The research of this project will contribute to a comprehensive understanding of the relevant influencing factors of ferroelectric thin film working process, provide a theoretical basis for improving device performance, and promote the development of flexoelectro-chemical coupling theory.

铁电薄膜材料被广泛应用于传感器和铁电存储器等智能器件中，铁电薄膜的性能决定了这些设备的智能化和多功能化。铁电薄膜工作环境复杂，容易受到力场、温度场、电场、化学过程等多场多过程的耦合影响。目前大部分研究只涉及到单向耦合或部分耦合，尤其是忽略了化学扩散过程与其他场之间的相互作用。基于此，本项目拟结合Landau-Ginzburg-Devonshire理论和非平衡热力学理论，发展考虑挠曲电效应、表面效应及化学扩散过程的非平衡力-挠曲电-化学扩散全耦合理论，建立挠曲电-化学耦合本构及演化方程，探究挠曲电系数、外加电场与薄膜厚度等因素对铁电薄膜铁电性能的影响；针对铁电薄膜断裂问题，本项目拟把Noether定理应用到铁电薄膜该耦合过程中，得到对应的守恒积分并计算能量释放率。本项目研究将有助于全面了解铁电薄膜工作过程的相关影响因素，为提高器件性能提供理论依据，并推动挠曲电-化学耦合理论的发展。

铁电薄膜材料被广泛应用于传感器和铁电存储器等智能器件中，铁电薄膜的性能决定了这些设备的智能化和多功能化。铁电薄膜工作环境复杂，容易受到力场、温度场、电场、化学过程等多场多过程的耦合影响。目前大部分研究只涉及到单向耦合或部分耦合，尤其是忽略了化学扩散过程与其他场之间的相互作用。基于此，本项目结合Landau-Ginzburg-Devonshire理论和非平衡热力学理论，发展了考虑挠曲电效应及化学扩散过程的非平衡力-挠曲电-化学扩散全耦合理论，建立了挠曲电-化学耦合本构及演化方程，探究了化学扩散对极化、浓度和位移的影响；针对断裂问题，本项目把Noether定理应用到该耦合过程中，得到对应的守恒积分并计算能量释放率。