Macroscopic and local piezoelectric properties of Pb(Mg _1/3Nb_2/3)O₃-PbTiO₃ single crystals exhibiting giant piezoelectric response

The temperature and bias field dependences of macroscopic, measured by pulsating load method, and local, measured by piezoresponse force microscopy, longitudinal piezoelectric responses have been studied in (001)-oriented flux-grown (1 - x)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO ₃ (0.0 x 0.29) single crystals. Both types of responses exhibit a dramatic enhancement with increasing bias fields. At the same time, their temperature maxima shift from the Vogel-Fulcher temperature to the vicinity of the dielectric permittivity maximum, where the critical point in the E-T phase diagram is located. Both datasets confirm a quasicritical nature of the giant field-induced piezoelectric response in relaxor single crystals.