Lead zirconate-titanate (PbZr_1−xTi_xO₃, PZT) is a piezoelectric perovskite material, which possesses ferroelectric as well as antiferroelectric properties. Thanks to high piezoelectric coefficient PZT is broadly used in many electronic devices [1].

For PZT with 0 < x < 0.06 antiferroelectric phase is stable at room temperature. This phase has an orthorhombic structure resulting from antiparallel displacements of lead ions and opposite rotations of ZrO₆ octahedrals for the neighboring layers of paraelectric cubic perovskite structure [2]. Thus, phase transition into the antiferroelectric phase is associated with condensation of two phonon modes with different symmetry. In paraelectric phase dielectric measurements [3] revealed critical divergence of dielectric constant, which could be associated with ferroelectric mode instability in Brillouin zone center. There is ferroelectric intermediate phase in-between the antiferroelectric and paraelectric phases. Electron diffraction indicates that the intermediate phase has incommensurate modulated structure [4], however, the symmetry of this phase is still not well understood.

To study microscopic mechanism resulting in PZT phase transitions the measurements of single crystal diffuse and inelastic X-ray scattering in PZT with 0.007 < x < 0.04 have been performed.  In the present contribution, the relevant critical dynamics accompanying phase transitions in Zr-rich PZT will be discussed using obtained results.

Andronikova D. acknowledges support by Russian President Grants No. SP-3762.2018.5

References:

[1] Haertling G. H. JACS, 82, 4, 1999
[2] Fujishita H. et.al., JPSJ, 53,1 1984
[3] Roleder K. et.al. Phase Transitions, 71, 287, 2000
[4] Watanabe S. et.al. PRB, 66, 2002