Giant piezoelectricity of Sm-doped Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ single crystals

High-performance piezoelectrics benefit transducers and sensors in a variety of electromechanical applications.The materials with the highest piezoelectric charge coefficients (d33) are relaxor-PbTiO₃ crystals, which were discovered two decades ago. We successfully grew Sm-doped Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (Sm-PMN-PT) single crystals with even higher d33 values ranging from 3400 to 4100 picocoulombs per Newton, with variation below 20%over the as-grown crystal boule, exhibiting good property uniformity.We characterized the Sm-PMN-PTon the atomic scale with scanning transmission electron microscopy and made first-principles calculations to determine that the giant piezoelectric properties arise fromthe enhanced local structural heterogeneity introduced by Sm3+ dopants. Rare-earth doping is thus identified as a general strategy for introducing local structural heterogeneity in order to enhance the piezoelectricity of relaxor ferroelectric crystals.