Pressure-Induced Anomalous Phase Transitions and Colossal Enhancement of Piezoelectricity inPbTiO3

Abstract

We find an unexpected tetragonal-to-monoclinic-to-rhombohedral-to-cubic phase transition sequence induced by pressure, and a morphotropic phase boundary in a pure compound using first-principles calculations. Huge dielectric and piezoelectric coupling constants occur in the transition regions, comparable to those observed in the new complex single-crystal solid-solution piezoelectrics such as Pb(Mg(1/3)Nb(2/3))O3-PbTiO3, which are expected to revolutionize electromechanical applications. Our results show that morphotropic phase boundaries and giant piezoelectric effects do not require intrinsic disorder, and open the possibility of studying this effect in simple systems.

Effects of tricritical points and morphotropic phase boundaries on the piezoelectric properties of ferroelectrics

“…We have seen this in equating Eqs. (8) and (10). A notable consequence of the above analysis is that for a vertical MPB anisotropy arises from sixth and higher order terms of the free energy expansion (the fourth order term is isotropic, as a ′ 4 = 0) and therefore the degree of anisotropy will be small, enhancing the piezoelectric response by means of the polarization rotation mechanism.…”

“…The piezoelectric response is usually a maximum in the vicinity of phase transitions due to the flattening of the free energy profile facilitating polarization extension and/or polarization rotation. [7][8][9][10][11] While polarization extension is usually the dominant mechanism in phase transitions from a nonpolar to a polar phase, such as the paraelectric cubic to ferroelectric tetragonal in BaTiO 3 , the polarization rotation mechanism is dominant in phase transitions between two polar phases with different crystal symmetry and different orientation directions of the polarization vector, such as the composition driven rhombohedral to tetragonal phase transition in PZT. 12,13 These ideas have led to the suggestion of a phase diagram which takes advantage of both mechanisms simultaneously by introducing a polar phase between another polar phase of a different symmetry and a nonpolar phase in a narrow region of the temperature-composition parameter space.…”

First-principles studies of lone-pair-induced distortions in epitaxial phases of perovskiteSnTiO3andPbTiO3

“…12, when performance, cost, ease of preparation and precursors availability are taken into account, PZT still remains the almost perfect all-around piezoelectric material. The exceptional piezoelectric properties of PZT, compared to only moderate piezoelectricity of PbTiO 3 , are attributed to the emergence of a morphotropic phase boundary (MPB) 3,[15][16][17][18] near the Zr:Ti = 52:48 and high mobility of FE domain walls, indicating that the existence of large PJTE-induced structural distortions is a necessary but not sufficient ingredient for attaining colossal property responses.…”

Ultrahigh electromechanical response in (1−x)(Na0.5Bi0.5)TiO3-xBaTiO3 single-crystals via polarization extension

“…8 It has been shown that phase transitions near MPBs between R and T phases actually occur by structurally bridging intermediate monoclinic (M) phases. 9 The high electromechanical responses are then believed to relate to symmetry-allowed polarization rotations [10][11][12][13] during which the transverse dielectric susceptibility v 11 and shear piezoelectric coefficient d 15 are enhanced as discussed by Damjanovic. [14][15][16][17][18][19] The large piezoelectric response along non-polar axes is, then, a consequence of the large v 11 and d 15 values.…”