Temperature-dependent structure and electromechanical properties of Er doped PMN-PT single crystal grown by modified Bridgman technique

In this work, the Er-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal with a large size was successfully grown by the modified Bridgman technique. The temperature dependent phase structure, domain configuration and electromechanical properties of the single crystal with the composition of 2 wt%Er-0.66PMN-0.34PT (Er-0.66PMN-0.34PT) were investigated in detail. For [001]C oriented Er-0.66PMN-0.34PT single crystal, it is found that the room temperature phase structure is the coexistence of rhombohedral (R) and monoclinic (M) phases and M phase is dominated. The piezoelectric constant d33 through the converse piezoelectric effect is about 2410 pC/N. The phase transition from R+M to tetragonal (T) phase begins at 80 ℃ and finishes at 120 ℃. Between 80 ℃ and 120 ℃, the single crystal belongs to the coexistence of R, M and T phases. At 135 ℃, the T phase and polar nanoregions (PNRs) transform into cubic phase and PNRs. The compliance constantss33Dand s33E, longitudinal coupling factor k33 and piezoelectric constant d33 increase by 32%, 77%, 34% and 133%, respectively, with temperature increasing from 22 ℃ to 80 ℃. The ultrahigh increase of d33 is derived from the increase of dielectric constant due to easier polarization rotation and domain wall movement at elevated temperature. Our results will helpful for the study of rare-earth doped relaxor ferroelectric single crystals.