A thin-film bilayer structure consisting of polycrystalline Pb0.85Sm0.1TiO3 (PST) and preferentially (1 1 1)-orientated Bi2Ti2O7 were prepared using sol-gel technique. The structural properties were studied by X-ray diffraction. We compared the memory properties and retention time of PST/Bi2Ti2O7 with those of PST, respectively. The results show that because of the intervention of Bi2Ti2O7, it needs lower voltage to cause the inversion of spontaneous polarization, and the memory window becomes symmetrical. The PST/Bi2Ti2O7 film in the ON and OFF states is relatively stable compared to PST film. (C) 2004 Elsevier B.V. All rights reserved.