多晶铁电薄膜的双层结构模型

实验观察发现：多晶钛酸铅铁电薄膜的表面层与体内层有不同的结晶和相变特性。根据实验结果，可假设多晶铁电薄膜具有与铁电微粉类似的特征，将表面层描述为小晶粒低应变层；体内层描述为大晶粒高应变层；所有晶粒均被一薄的非铁电层覆盖。

A DOUBLE LAYER MODEL OF POLYCRYSTALLINE FERROELECTRIC THIN FILMS

It is experimentally investigated that the crystallography properties and phase transition property of the surface layer of the lead titanate polycrystalline thin films are different from those of bulk layer. According to the experimental results, the surface layer is described as a layer with smaller crystallite size and weakly stressed; and the bulk layer is described as a layer with larger crystallite size and highly stressed; All the crystallites are covered by a thin nonferroelectric layer. A double layer model is presented to analyze the differences. The formation of the double layer structure is described. Influences of the special structure on the di-electric properties, such as dielectric constant and coercive field, and phase transition proper-ties of the film are analyzed with the double layer model.