Fabrication and electrical properties of sol-gel-derived relaxor ferroelectric thin films

A sol-gel derived Pb(Mg_1/3 Nb_2/3)_0.7Ti_0.3O₃ (PMNT) relaxor ferroelectric thin film was prepared by using a spin coating and a PbO cover coat technique. The amount of lead excess in the precursor solution had significant effects on the phase development and microstructure of the PMNT film. The PbO cover coat was proved to be effective on suppressing the formation of pyrochlore phases. PMNT thin films with a pure perovskite structure were obtained by adding 30 mol% excess lead in the precursor solution and coating the PbO layer on the top. A dynamic growth mechanism for PMNT thin films was proposed briefly. The electrical property of the perovskite PMNT films was analyzed by measuring the temperature and frequency dependence of the dielectric constant and loss as well as the polarization hysteresis loop.