Domain morphology of newly designed lead‐free antiferroelectric NaNbO₃‐SrSnO₃ ceramics

Abstract

Reversible antiferroelectric-ferroelectric phase transitions were recently observed in a series of SrSnO 3 -modified NaNbO 3 lead-free antiferroelectric materials, exhibiting well-defined double polarization hysteresis loops at ambient conditions. Here, transmission electron microscopy was employed to investigate the crystallography and domain configuration of this newly designed system via electron diffraction and centered dark-field imaging. It was confirmed that antiferroelectricity is maintained in all compositions, manifested by the characteristic ¼ superlattice reflections in the electron-diffraction patterns. By investigating the antiferroelectric domains and domain boundaries in NaNbO 3 , we demonstrate that antiphase boundaries are present and their irregular periodicity is responsible for the streaking features along the ¼ superlattice reflections in the electron-diffraction patterns. The signature domain blocks observed in pure NaNbO 3 are maintained in the SrSnO 3 -modified ceramics, but disappear when the amount of SrSnO 3 reaches 7 mol.%. In particular, a well-defined and distinct domain configuration is observed in the NaNbO 3 sample modified with 5 mol.% SrSnO 3 , which presents a parallelogram domain morphology.

Tailoring high-energy storage NaNbO3-based materials from antiferroelectric to relaxor states

“…1g ). Upon the application of large electric fields, the NN5SS sample transforms into the FE state at E AFE−FE , whereby the moving phase boundary 15 , 33 and the changed domain state 34 facilitate a redistribution of free charges. These are likely to accumulate at grain boundaries, thereby forming a local electric field that partially stabilizes the induced FE state and is responsible for the large remanent polarization.…”

“…2a ) and is characterized by homogeneous domain morphology (Fig. 2d ) and uniform lattice fringes, interrupted by the antiphase boundaries (APBs) with darker line contrast 34 (Fig. 2g ).…”

Energy storage performance of NaNbO3 lead-free dielectric ceramics by doping Sr(Mg1/3Sb2/3)O3

“…The inhomogeneity of the local structure may be related to the generation of vacancy defects and the nonequivalent substitution of NN-SMSb ceramics. [20][21][22][23] The size of the nano-domains affects its response speed to the electric field, [24][25][26] and the smaller nano-domains require a higher electric field to induce the generation of micro-domains, 22,[27][28][29] which may be one of the reasons why the polarization of the ceramic changes with E. In Fig. 2(c) and (d), 1/2{ooe} and 1/2{ooo} superlattice spots can be observed, indicating the existence of a local tetragonal phase in 0.10NN-SMSb and 0.13NN-SMSb ceramics, [30][31][32] which is consistent with the XRD analysis.…”

Revealing the mechanism of electric-field-induced phase transition in antiferroelectric NaNbO3 by in situ high-energy x-ray diffraction

“…The small delay of the macroscopic response can be partially ascribed to the limited time resolution of the measurement (patterns were collected over a time of 415 ms, during which the field increased by 0.67 kV/mm). The critical electric fields for the transitions between individual stages are also expected to be frequency 5 and grain size 40 dependent. Structural and microstructural changes during the stages will be discussed in more detail below.…”

“…Na(1) displacements in a direction close to <110>PC, whereby the sequence of these displacements is antiparallel in consecutive cells along the [001]PC axis 42 (Figure 1). The domain structure consists of orientational domains with antipolarization 43,44 . During stage I, the E-field is not strong enough to induce the AFE-FE phase transition and electrostatically neutral domains are not affected.…”