  Relaxor ferroelectrics exhibit a unique competition between long-range and
short-range interactions that can be tuned electrically which prioritizes these
materials in a broad range of electro-mechanical energy-conversion
technologies, including biomedical imaging and electric-charge generators.
Here, we demonstrate differential negative piezoresponse by utilizing the
short-range interactions in relaxor ferroelectrics. The effect was observed
over a broad temperature range with local piezoresponse spectroscopy in unpoled
samples, while no negative piezoresponse was observed when the material was
pre-scan poled. These measurements suggest that the effect, that is promising
for power-generation applications, originates from non-ergodic behavior.
Complementary macroscale impedance and dielectric constant measurements as a
function of temperature and frequency supported the mesoscopic findings.
Bearing in mind the direct relationship between piezoresponse and capacitance,
relaxor ferroelectrics appear as an excellent platform for the emerging
technology of low-power negative-capacitance transistors.
