Dielectric and piezoelectric properties of prestressed Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystals under alternating and direct current poling

This study investigates the effect of prestress during the electric poling of [001]-cut Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) piezoelectric single crystals under both alternating current poling (ACP) and direct current poling (DCP). The samples were poled under various levels of mechanical stress and characterized via dielectric, piezoelectric, strain–electric field, and temperature-dependent measurements. It was found that samples poled via ACP with intermediate prestresses between 10 and 18 MPa showed an 8% and 10% increase in d33 and dielectric permittivity ε33T/ε0, respectively, compared to samples without prestress. At 18 MPa, the measured values of d33 and dielectric permittivity were 2470 pC/N and 8340, respectively, under ACP with a 15 kV/cm peak-to-peak electric field. In contrast, there was no obvious enhancement in the samples poled via DCP with prestress compared to without prestress. It was also found that prestress leads to increasing dielectric loss factors for the poled crystals under either ACP or DCP. The polarization loop data suggested that prestress can increase the coercive fields for ACP samples. Moreover, temperature-dependent experiments revealed that prestressed samples have significantly elevated dielectric constant and d33 at higher temperatures (above 93 °C). PFM scans showed that poling samples in the presence of prestress resulted in finer and more densely packed domains. These findings demonstrate that the combination of mechanical prestress and ACP poling can provide an effective route for engineering domain structures in PMN-PT single crystals suitable for advanced piezoelectric device applications.