Electric field-induced polarization rotation and ultrahigh piezoelectricity in PbTiO3

Polarization rotation, phase changes, and piezoelectric property of PbTiO3 under high electric field have been investigated using a Landau-Ginzburg-Devonshire phenomenological approach. Electric field versus temperature phase diagram has been constructed. Tetragonal (T)-monoclinic (M-A)-rhombohedral (R) phase transition occurs when electric field is applied along pseudo-cubic [111] axis, and piezoelectric coefficient d(33) is remarkably enhanced near the critical electric field for MA-R transition. With electric field applied along pseudo-cubic [011] axis, the polarization rotation involves the other two monoclinic phases (M-B and M-C), and ultrahigh d(33) over 8000 pC/N has been found at the monoclinic-orthorhombic (M-O) transition region. The critical field for M-O transition (similar to 1000 MV/m) can be greatly lowered under hydrostatic pressure. Based on the reported strain gradient induced polarization rotation in epitaxial film, flexoelectric coefficient mu(12) of PbTiO3 is estimated to be similar to 156-312 nC/m at room temperature. (C) 2014 AIP Publishing LLC.