Ferroelectric thin films of bismuth-containing layered perovskites: Part II, PbBi2Nb2O9

Ferroelectric thin films of bismuth-containing layered perovskite PbBi2Nb2O 9 have been prepared by a metalorganic decomposition (MOD) method. Random a nd highly c-oriented films of the same starting composition have been obtai ned under different intermediate- and high-temperature heat treatments. A c omparison of their crystallization and properties with those of Bi4Ti3O12 f ilms reveals similar trends that are common to bismuth-containing Au-rivill ius compounds. Heterogeneous nucleation of the perovskite phase either on t he pyrochlore (444) plane because of lattice matching or on the substrate s urface because of lower interfacial energy is proposed as the cause of orie ntation selection during crystallization. The different thickness of the ps eudoperovskite subunits in these layered compounds may be responsible for t he systematic difference in the anisotropic ferroelectric properties. Small er polarization and higher coercive field are expected for PbBi2Nb2O9, whic h has thinner pseudoperovskite units than Bi4Ti3O12.