EFFECT OF NB DOPING ON THE MICROSTRUCTURE OF SOL-GEL-DERIVED PZT THIN-FILMS

Aliovalent Nb doping (less than or equal to 10 at.%) of sol-gel-derive d lead zirconate titanate (PZT) thin films was investigated with the i ntention of improving the ferroelectric properties. Nb addition was fo und to significantly alter the perovskite crystallization by stabilizi ng the transient pyrochlore phase, resulting in the retention of pyroc hlore second phases and an increase in the perovskite lateral grain si ze and columnarity. The occurrence and composition of Zr-rich (surface ) pyrochlore phases were found to depend on Nb concentration, annealin g temperature, and Pb content. The observed changes in ferroelectric a nd dielectric properties as a function of Nb dopant addition were foun d to be strongly influenced by microstructural effects and the occurre nce of pyrochlore, and hence the intrinsic effects of Nb incorporation in the perovskite lattice could not be directly ascertained.