Stability of ferroic phases in the highly piezoelectric Pb(Zr_xTi_1−x)O₃ceramics

Abstract

The morphotropic phase boundary in the phase diagram of the technologically important Pb(Zr x Ti 1Àx )O 3 (PZT) ceramics has been traditionally believed to separate ferroelectric tetragonal and rhombohedral phase regions. This old picture has come under close scrutiny during the last eight years following the discovery of new monoclinic phases in the Cm and Cc space groups. This article presents a brief overview of these discoveries in which the use of multiple diffraction probes (X-ray, electron, neutron diffraction) in conjunction with physical property measurements has played a crucial role. A new phase diagram of PZT showing the stability fields of these structures below room temperature is also presented.

Strain Mechanisms in Lead-Free Ferroelectrics for Actuators

“…The role of low symmetry phases such as O or M has been pointed out in several works as a fundamental aspect to realize a high electromechanical response due to facilitated reorientation of . [170][171][172][173][174][175][176] The results of this work indicate that the low symmetry interleaving region promotes non-180° domain switching ( )). The high degree of non-reversible switching enables a maximized 33 and , while the high overall switching contribution leads to considerably enhanced 33 , , and 33 * .…”

“…156 The MPB region marked with point in Figure 2.16 has been generically characterized as O or Monoclinic (M) phases. [170][171][172][173][174][175][176] This interleaving region was proposed to be a bridge phase between the nearby phases B and C, as there is no group-subgroup relation between the commonly found 4 / 4 and 3 symmetries. It was stated that these phases aid reorientation, indicating that this model mostly rationalizes intrinsic contributions.…”

Elastic and anelastic relaxation behaviour of perovskite multiferroics I: PbZr0.53Ti0.47O3 (PZT)–PbFe0.5Nb0.5O3 (PFN)

“…The loss peak measured at kHz frequencies remains discernible in the vicinity of the MPB, but its influence on the Young's modulus is much harder to see [44,49,109]. The minimum in Young's modulus is sharp when measurements are made on poled samples [52,60,113,114]. A single measurement of longitudinal acoustic velocity through a sample of Pb(Zr 0.53 Ti 0.47 )O 3 showed a small rounded minimum with a slight hysteresis [61].…”

“…If there is any associated anomaly in Q À1 , it is perhaps only a slight increase with falling temperature through the transition at both Hz and kHz frequencies [49,[105][106][107]109]. By way of contrast, a poled sample of Pb(Zr 0.52 Ti 0.48 )O 3 displayed a sharp minimum in the Young's modulus measured at *150 kHz [52,60,113,114]. The difference is presumed to reflect a difference in microstructure, with the unpoled sample having a higher density of nanoscale twinning.…”

“…As discussed above, this same transition may also occur along the PZ-PFN binary join and would give a stability field for the R3c structure extending into the ternary system at room temperature. In the stability field of the monoclinic structure below the MPB of PZT, the same octahedral tilting transition involves the symmetry change Cm-Cc [57][58][59][60][61][62], but no information is yet available to determine whether this occurs in the ternary system as well. In (Pb 0.94 Sr 0.06 )(Zr 0.55 Ti 0.…”