Connecting the Multiscale Structure with Macroscopic Response of Relaxor Ferroelectrics

Abstract

Lead-based relaxor ferroelectrics are characterized by outstanding piezoelectric and dielectric properties, making them useful in a wide range of applications. Despite the numerous models proposed to describe the relation between their nanoscale polar structure and the large properties, the multiple contributions to these properties are not yet revealed. Here, by combining atomistic and mesoscopic-scale structural analyses with macroscopic piezoelectric and dielectric measurements across the (100-x)Pb(Mg 1/3 Nb 2/3) O 3-xPbTiO 3 (PMN-xPT) phase diagram, a direct link is established between the multiscale structure and the large nonlinear macroscopic response observed in the monoclinic PMN-xPT compositions. The approach reveals a previously unrecognized softening effect, which is common to Pb-based relaxor ferroelectrics and arises from the displacements of low-angle nanodomain walls, facilitated by the nanoscale polar character and lattice strain disorder. This comprehensive comparative study points to the multiple, distinct mechanisms that are responsible for the large piezoelectric response in relaxor ferroelectrics.

The mechanism for the enhanced piezoelectricity in multi-elements doped (K,Na)NbO3 ceramics

“…Interestingly, the rare-earth-doped PMN-PT ceramics with enhanced piezoelectric coefficient also exhibit increased volume fraction of tetragonal phase with reduced Curie temperature and broad relaxation peak 31,36 . Tetragonal phase with low-angle domain wall was also observed in the structure evolution of PMN-PT solid solution with increasing Ti concentration based on the molecular dynamic calculation and STEM observation, being considered responsible for its high piezoelectric properties 26,37,38 .…”

Frequency-dependent suppression of field-induced polarization rotation in relaxor ferroelectric thin films

“…Our combined results of in operando X-ray diffraction, STEM, and ferroelectric switching studies show the suppression of polarization rotation at ultrasonic frequencies (a 20 kHz), 13 which is hypothesized to be due to the existence of a high density of low-angle domain walls in relaxors. 5,12,15,16,26 Recent theoretical studies estimated that the domain-wall regions in PMN-PT can have an extremely high piezoelectric coefficient (d 33 > 30,000 pC/N) and thus may play a key role in ultrahigh piezoelectricity in relaxors. 8 The in operando X-ray diffraction results suggest that the mesoscale domain structures are strongly coupled to the average unit-cell structures and thus have dominant effects on the dynamics of polarization rotation.…”

Dielectric and electro-mechanic nonlinearities in perovskite oxide ferroelectrics, relaxors, and relaxor ferroelectrics

“…A representation of the field dependence in terms of real and imaginary components of P (3) and x (3) could be helpful for additional analysis, as demonstrated in Ref. [7]. Normalized permittivity and piezoelectric coefficients presented in Figure 4 show that the relative deviation between nonlinear polarization and strain response increase towards rhombohedral compositions.…”

“…For a more detailed analysis it can be useful to analyze the real and the imaginary parts of harmonic components in addition, as done in Ref. [7].…”