【摘要】 以二级相变铁电材料为例,利用推广的Ginzburg-Landau-Devonshire(GLD)理论,研究不均匀结构对梯度铁电薄膜性质的影响.结果表明:退极化场对于两层薄膜中间的极化影响较小,而在薄膜的两端处影响最大;梯度铁电薄膜的平均极化随膜厚按线性规律变化;在接近相变温度时,自发极化消失,梯度铁电薄膜的这一现象与铁电材料的性质相同.在外场不等于零的情况下,得到的梯度铁电薄膜的电滞回线中心对称.更多还原

【Abstract】 Using the generalized theory of Ginzburg-Landau-Devonshire,the influence of inhomogeneous structure on properties of gradient ferroelectric film is studied.We take the ferroelectric material with the second order phase transition as an example to complete numerical calculation.The results showed that the influence of depolarization field on the middle of gradient ferroelectric film is larger than that toward each end.The average polarization of gradient ferroelectric film varys linearly with the thickness of film.When the reduced temperature is equal to 1,spontaneous polarization vanishes.This phenomenon of gradient ferroelectric film is identical with that of bulk ferroelectric material.When the external field is not equal to zero,electric hysteresis loop we obtained is centrosymmetry.更多还原