Large piezoelectric response in (111)-oriented epitaxial Pb(Zr,Ti)O3 films consisting of mixed phases with rhombohedral and tetragonal symmetry

Abstract

Pb ( Zr,Ti ) O 3 films with a Zr/(Zr+Ti) ratio of 0.48 having 1.5 μm in thickness were grown on (100)c-, (110)c-, and (111)c-oriented SrRuO3//SrTiO3 substrates by metalorganic chemical vapor deposition. It was ascertained by θ–2θ scans of x-ray diffraction that (001)T-/(100)T-/(100)R-, {110}-, and {111}-oriented films were epitaxially grown on (100)c-, (110)c-, and (111)c-oriented substrates. Polarization and field-induced strain in these films were simultaneously observed through a scanning probe microscope that was attached to a ferroelectric test system. About three times larger field-induced strain than that on other substrates was observed together with the largest spontaneous polarization for a film grown on a (111)cSrRuO3//(111)SrTiO3 substrate. High-resolution x-ray diffraction analysis suggested that the film grown on the (111)cSrRuO3//(111)SrTiO3 substrate consisted of rhombohedral and tetragonal mixture phases. Its crystal structure possibly contributed to the large piezoelectric response.