Perovskite Formation of Pb(Mg1/3Nb2/3)O3 and Pb(Fe1/2Nb1/2)O3 Film by Sol-Gel Method

Dielectric thin films of Pb(Mg1/3Nb2/3)O3 and Pb(Fe1/2Nb1/2)O3 were prepared by sol-gel method. The Pb(Mg1/3Nb2/3)O3 perovskite film was formed by heat treatment at over 600°C and oriented on substrates whose interplanar spacings were close to that for the perovskite. On the other hand, Pb(Fe1/2Nb1/2)O3 perovskite appeared at below 500°C. It was not oriented in spite of having almost the same lattice parameters. Transmission electron microscopy revealed that Pb(Mg1/3Nb2/3)O3 perovskite nucleation occurs at specific places on the substrate, while Pb(Fe1/2Nb1/2)O3 occurs randomly in the film. The grain of these films grew larger than 0.1 µm, and the dielectric constant was 1800 for the PMN film.