Origin of ultrahigh piezoelectricity in relaxor-PbTiO3 single crystals
In plain words
Crystals of lead magnesium niobate mixed with lead titanate deform several times more per applied voltage than conventional piezoelectric ceramics. Whether this comes from easy rotation of the dipole direction or from the disordered polar patches is debated.
Precise statement
Rhombohedral PMN-xPT near the morphotropic phase boundary ($x\sim 0.3$), poled along $[001]$, has a longitudinal piezoelectric coefficient d33 several times that of lead zirconate titanate ceramics. Determine the fractional contributions of polarization rotation through monoclinic phases, local structural heterogeneity (polar nanoregions, claimed as 50 to 80 percent of the room-temperature response by Li et al., Nature Communications 2016) and domain-wall motion, from a calculation or experiment that reproduces d33(T, x). An answer is a quantitative partition with uncertainty.
What would settle it
Temperature- and composition-resolved d33 compared with atomistic simulations in which each contribution can be switched off.