人工复合铁电薄膜的相变性质研究

Investigation on Phase Transition Properties of Artificial Composite Ferroelectric Thin Films

建立3层铁电复合薄膜的理论模型,在G inzburg-Landau-Devonsh ire(GLD)唯象理论的框架下,引入局域分布函数描述不同材料间过渡层的性质,重点研究具有不同相变温度的铁电材料复合而成的铁电薄膜的相变性质.通过改变3种不同铁电材料的相变温度,计算复合铁电薄膜内部的极化强度分布和相变温度.研究表明:3种铁电材料相变温度的梯度变化导致了复合薄膜内部极化分布的梯度变化;在未达到薄膜的相变温度前,薄膜的平均极化强度的一阶导数出现了一个突降,造成了平均极化强度的极大降低;不同材料间过渡层厚度对薄膜内部极化分布影响显著,而对平均极化强度和相变温度影响不大.

A theoretical model of three components composite ferroelectric thin film was setup.In the frame of Ginzburg-Landau-Devonshire（GLD） theory,a local distribution function was introduced to describe the properties of the transition layers,and the phase transition properties of the ferroelectric thin films composed of three ferroelectric materials with different transition temperatures were mainly investigated.Changing the phase transition temperatures of three different ferroelectric materials,the polarization distribution in the film and the phase-transition temperatures were calculated.The results were shown that the gradient variation of phase-transition temperatures of the three materials leads to the gradient polarization distribution in the film;before the phase-transition point,the first derivative of the mean polarization occurs a sudden decrease,which lead to a great decrease of mean polarization;the thickness variation of transition layers had obvious influence on polarization distribution,while had little influence on mean polarization and phase-transition temperatures.