Electric-field-induced strain contributions in morphotropic phase boundary composition of (Bi1/2Na1/2)TiO3-BaTiO3 during poling

Abstract

The microscopic contributions to the electric-field-induced macroscopic strain in a morphotropic 0.93(Bi1/2Na1/2TiO3)−0.07(BaTiO3) with a mixed rhombohedral and tetragonal structure have been quantified using full pattern Rietveld refinement of in situ high-energy x-ray diffraction data. The analysis methodology allows a quantification of all strain mechanisms for each phase in a morphotropic composition and is applicable to use in a wide variety of piezoelectric compositions. It is shown that during the poling of this material 24%, 44%, and 32% of the total macroscopic strain is generated from lattice strain, domain switching, and phase transformation strains, respectively. The results also suggest that the tetragonal phase contributes the most to extrinsic domain switching strain, whereas the lattice strain primarily stems from the rhombohedral phase. The analysis also suggests that almost 32% of the total strain is lost or is a one-time effect due to the irreversible nature of the electric-field-induced phase transformation in the current composition. This information is relevant to on-going compositional development strategies to harness the electric-field-induced phase transformation strain of (Bi1/2Na1/2)TiO3-based lead-free piezoelectric materials for actuator applications.

In-situ XRD study of actuation mechanisms in BiFeO3-K0.5Bi0.5TiO3-PbTiO3 ceramics

“…Therefore, the phase transformation is a dynamic and competitive process for both intrinsic and extrinsic contributions before reaching a stable state, where the extrinsic effect is gradually enhanced during the two complete cycles of the electric field. However, the intrinsic strain is still dominant with a major contribution after the first half cycle (around 2.5×10 -3 at 5 kV/mm) compared with the extrinsic strain (around 1.5×10 -3 at 5 kV/mm); this is somewhat different to previous observations in normal ferroelectrics, where the extrinsic contributions tend to be more pronounced or close to that of the intrinsic effect [17,21]. Furthermore, 33 varies more sensitively with the applied electric field compared with the corresponding behavior of ε 33 , which exhibits a tendency for saturation.…”

“…This may lead to the misinterpretation of the measured XRD patterns if suitable physical models are not utilised in the fitting procedures. Therefore, single peak profile fitting and full pattern refinement methods incorporating such models have been proposed in order to address these problems [15][16][17][18]. For both of these approaches, the crystallographic parameters corresponding to the unpoled state are required to precisely evaluate the electric field-induced strain.…”

Origin of ferroelectric P‐E loop in cubic compositions and structure of poled (1‐x)Bi(Mg1/2Zr1/2)O3‐xPbTiO3 piezoceramics

“…The c ‐axis lattice strain was calculated using lattice parameters of poled and unpoled samples as: Lattice strain (%) = × 100. Similar to our results, transformation of pseudocubic/rhombohedral phase in to the coexistence of two phases by application of electric‐field is reported in several Bi 1/2 Na 1/2 TiO 3 ‐based solid solutions . The mixed phases persist even after removal of the electric‐field.…”

Critical Role of Monoclinic Polarization Rotation in High-Performance Perovskite Piezoelectric Materials

“…S1(a), of the Supplemental Material [ 26 ]), the 4 diffraction patterns at the 45° sectors contain negligible effects of preferred 5 orientation, which allows extracting the important piezoelectric-related structure 6 information, such as the polarization rotation behavior. This strategy to minimize the 7 effect of preferred orientation is analogous to the important method reported by 8 Hinterstein et al [16,36]. The in-situ diffraction data were collected during the 9 unloading procedure from an electric field near the coercive field (E C ) to zero electric 10 field (E = 0 kV/mm).…”