Cation ordering in epitaxial lead zirconate titanate films

Abstract

Electron diffraction and atom location by channeling enhanced microanalysis were used to show that epitaxial PbZr0.2Ti0.8O3 films grown on (001) SrTiO3 substrates by pulsed laser deposition exhibit long-range order on the tetravalent cation sublattice parallel to the film/substrate interface. This ordering gives two distinct tetravalent cation sites, one Zr lean and one Zr rich, and results in a superlattice with a tetragonal unit cell with lattice parameters a(0)approximate to root 2a(PZT) and c(0)approximate to a(PZT). Since such ordered states are inherently unstable in homovalent perovskite solutions, it is inferred that the ordering arises in response to the lattice misfit and could constitute an additional relaxation mode.