Preparation and characterization of sol-gel-derived lead magnesium niobium titanate thin films with pure perovskite phase and lead oxide cover coat

A sol-gel-derived Pb(Mg_1/3Nb_2/3)_0.7Ti_0.3O₃ (PMNT) thin film was prepared using 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 proved to he 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 of the film. The remnant polarization (P_r), the dielectric constant (ε_r), and the dissipation factor (tan δ) of these thin films, which had a thickness of 150 nm, were determined to be 9 μC/cm², 1370, and 0.031, respectively.