Characterization of the Piezoelectric Properties of Pb0.98Ba0.02(Mg1/3Nb2/3)O3–PbTiO3 Epitaxial Thin Films

Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) (70/30) thin films were deposited by pulsed laser deposition using two growth strategies: adsorption controlled deposition from lead-rich targets (∼25–30 mass%) and lower-temperature deposition (Td≤600°C) from targets containing a small amount of excess lead oxide (≤3 mass %). The substrates used were (001) SrRuO3/LaAlO3. Typical remanent polarization values ranged between 12 and 14 μC/cm2 for these films. The longitudinal piezoelectric coefficient (d33,f) was measured using in situ four-circle X-ray diffraction, and the transverse coefficient (d31,f or e31,f) was measured using the wafer flexure method. d33,f and e31,f coefficients of ∼300–350 pm/V and ∼−11 C/m2 were calculated, respectively. In general, the piezoelectric coefficients and aging rates were strongly asymmetric, suggesting the presence of a polarization bias. The large, extremely stable piezoelectric response that results from poling parallel to the preferred polarization direction is attractive for miniaturized sensors and actuators.