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论文采用动态金茨堡-朗道(DGL)方程研究了薄膜厚度与错配应变对(0 0 1)取向单畴外延PbTiO3(PTO)铁电薄膜相结构与稳定性的影响.结合平面内松弛应变(等效应变)、表面效应与退极化场等机电耦合边界条件,通过数值求解DGL方程获得外延单畴铁电薄膜错配应变-厚度相图和错配应变-温度相图.数值分析结果显示,由于生成的界面位错松弛了薄膜内错配应变,在理论高应变区相图与传统分析结果有较大差别,文中发现在更广的理论错配拉应变区出现稳定的四方相(c相)结构和单斜相(r相)结构.结果也显示,随着薄膜厚度的减小,表面效应与退极化效应会把顺电相扩展到更低温度区域,从而压缩稳定的铁电相存在的温度区域.
The effects of film thickness and mismatch strain on the structure and stability of (0 0 1) oriented single domain epitaxial PbTiO3 (PTO) ferroelectric thin films were investigated by the dynamic Gurley-Landau equation (DGL) Strain (equivalent strain), surface effect and depolarization field and other electromechanical coupling boundary conditions, obtained by the numerical solution of DGL equation obtained epitaxial single domain ferroelectric thin film misfit strain - thickness phase diagram and mismatch strain - temperature phase diagram. Numerical analysis The results show that due to the relaxation of interfacial mismatch strain caused by dislocations generated in the interface, there is a great difference between the theoretical high strain region phase diagram and the traditional analysis results. It is found that in the wider theoretical mismatch strain zone, stable tetragonal phase (c-phase) structure and the monoclinic phase (r-phase) structure.The results also show that the surface effect and depolarization effect will extend the paraelectric phase to a lower temperature region as the film thickness decreases, so that the compressively stable iron Electrical phase exists in the temperature range.