Combinatorial discovery of a lead-free morphotropic phase boundary in a thin-film piezoelectric perovskite

We report on the discovery of a lead-free morphotropic phase boundary (MPB) in Sm doped BiFeO(3) with a simple perovskite structure using the combinatorial thin film strategy. The boundary is a rhombohedral to pseudo-orthorhombic structural transition which exhibits a ferroelectric to antiferroelectric transition at approximately Bi(0.86)Sm(0.14)FeO(3) with dielectric constant and out-of-plane piezoelectric coefficient comparable to those of epitaxial (001) oriented PbZr(0.52)Ti(0.48)O(3) (PZT) thin films at the MPB. The discovered composition may be a strong candidate of a Pb-free piezoelectric replacement of PZT. (C) 2008 American Institute of Physics.