Crystal structure, electrical properties, and mechanical response of (100)-/(001)-oriented epitaxial Pb(Mg1/3Nb2/3)O 3-PbTiO3 films grown on (100)cSrRuO 3∥(100)SrTiO3 substrates by metal-organic chemical vapor deposition

摘要

Relaxor-type ferroelectric (1-x)Pb(Mg1/3Nb2/3)O 3-xPbTiO3 (PMN-PT) films, 2-3 μm in thickness, with a PbTiO3 content (x) ranging from 0 to 1 were grown on (100) cSrRuO3∥(100)SrTiO3 substrates at 650°C by metal-organic chemical vapor deposition. The effects the x value had on the crystal structure, dielectric and ferroelectric properties, and mechanical response of these films were systematically investigated. Epitaxial growth having (100)/(001) orientation irrespective of x and the constituent phase change with x were ascertained from both x-ray diffraction reciprocal space mapping analysis and Raman spectroscopy. The constituent phase changed from a rhombohedral (pseudocubic) single phase, a mixture phase of rhombohedral (pseudocubic) and tetragonal phases, and a tetragonal single phase, with increasing x. The mixed phase region was found to exist at x=0.40-0.55, which was different from that reported for single crystals (x=0.31-0.35). The dependencies of relative dielectric constant and remanent polarization on x showed a similar trend in the case of a PMN-PT sintered body; however, the magnitudes of these values were relatively low. The effective longitudinal piezoelectric coefficient (d33,f) and the transverse coefficient (e31,f) of 100-120 pm/V and ∼-11.0 C/m2 were, respectively, calculated for a film with x=0.39, which corresponds to a larger x edge for the rhombohedral (pseudocubic) region following the engineered domain concept proposed for PMN-PT single crystals.