Study on the structure and ferroelectric properties of sol-gel derived Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ thin films

92%Pb(Mg_1/3Nb_2/3)O₃-8%PbTiO₃ (PMNT) thin films on Pt/TiO₂/SiO₂/Si substrates with and without a LaNiO₃ (LNO) buffered layer have been prepared using a sol-gel method. Structures and electrical properties of these two films have been investigated and compared. Highly (111)-oriented PMNT thin films with some amounts of pyrochlore phase are obtained on bare Pt electrodes. On the contrary, (100)-oriented PMNT thin films with pure perovskite phase are formed on Pt electrodes with a LNO buffered layer. Electrical properties of the PMNT thin films are highly improved by using the buffered layer LNO. It is found that the remanent polarization (P_r) and the dielectric constant for the PMNT film with a LNO buffered layer are larger than that for the film without a LNO buffered layer.