Observation of 90° domain walls in relaxor ferroelectrics PMN-28.6%PT by focusing upon the CTR scattering

Self Cite

The shapes and sizes of grains influence the anisotropy of crystal structures and the configuration of ferroelectric domains. In order to better understand these effects, we introduce a method to observe a ferroelectric phase transition in a single ferroelectric particle of sub-micrometer size. The phase transition was observed by cooling the sample through its Curie temperature, and studying the pattern variations of Bragg coherent X-ray diffraction from a single particle of 500-nm-sized BaTiO3. A change from a single 200 peak (cubic phase) to both 200 and 002 peaks (tetragonal phase); was seen, with fringes connecting them like a bridge. The pattern from the BaTiO3 particle in the cubic phase was also imaged using Bragg coherent diffraction imaging. The apparent strain distribution caused by dislocation internal to the BaTiO3 crystal was visible in the reconstructed image.

“…The steps shown in Ref. 40 are followed in the model calculation. The main idea for connecting the two adjacent domains as 90°domain was based on the theoretical results shown in Refs.…”

Section: Appendix: On the Bridged Bragg Reflectionsmentioning

confidence: 99%

Section: Appendix: On the Bridged Bragg Reflectionsmentioning

confidence: 99%

The ferroelectric phase transition in a 500 nm sized single particle of BaTiO₃ tracked by coherent X-ray diffraction

Oshime

Ohwada

Machida

et al. 2022

Self Cite

“…Although a detailed near-boundary structure is not available because of the inadequate spatial resolution, the spotted streak tail in the CXD pattern at 313 K suggests a domain wall of negligible width according to model calculations. 27,37) Notably, the domain boundary observed in the tetragonal phase [Fig. 5(b)] is at the same position as that of the phase boundary observed in the cubic phase [Fig.…”

Section: Resultsmentioning

confidence: 76%

“…3, from this analysis, because although the domain corresponding to 200 T2 and 002 T forms another boundary elsewhere, the volume of the 200 T2 domain is negligibly small. The 200 T1 and 002 T Bragg spots of BTO connected by the streak tail correspond to the adjacent 90°domains; 37) herein, 200 T1 and 002 T are named as the a-and c-domains, respectively. Figure 5(b) shows the reconstructed 3D outer shape of the BTO single grain consisting of a-and c-domains viewed from the same direction as that in Fig.…”

Section: Resultsmentioning

confidence: 99%

Lattice strain visualization inside a 400 nm single grain of BaTiO₃ in polycrystalline ceramics by Bragg coherent X-ray diffraction imaging

Oshime

Ohwada

Machida

et al. 2023

Self Cite

The degree of anisotropy and the domain arrangement of crystal structures in ferroelectrics are affected by the grain boundaries and by the shape and size of the grains. To understand the grain boundary effects that occur in ferroelectric ceramics, we introduce a technique for nondestructively observing the internal lattice strain distribution of a submicrometer-sized ferroelectric grain in polycrystalline materials. The ferroelectric phase transition of a single grain in the polycrystalline materials was evaluated by tracking the changes in the Bragg coherent X-ray diffraction patterns. The internal lattice strain distribution of the grains in the paraelectric phase was visualized via Bragg coherent X-ray diffraction imaging. A pair of 90° domains in the ferroelectric phase were also imaged in three dimensions, and showed a domain boundary correlated with the internal lattice strain caused by the stresses from the adjacent grains.

“…[4][5][6][7][8][9] For Pb(Mg, Nb)O 3 -PbTiO 3 and Pb(Zn, Nb)O 3 -PbTiO 3 with extraordinary high piezoelectric properties, their MPBs provide a bridging phase in monoclinic symmetry 3,[10][11][12] that enables a rotation of the spontaneous polarization (P s ) vector. 10,[13][14][15][16][17][18][19][20][21][22] To establish an MBP similar to the PZT system, various lead-free solid solution systems have been investigated and composition-driven variations of crystal structure and properties have been studied. Since the discovery of (K, Na)NbO 3 -based ceramics with properties comparable to PZT, 23) (K, Na)NbO 3 [24][25][26][27][28][29][30] and its related Nb-based materials [31][32][33][34][35][36] have intensively studied with the aim of developing lead-free piezoelectric devices.…”

Section: Introductionmentioning

confidence: 99%

Ferroelectric polarization of tetragonal BiFeO₃—an approach from DFT calculations for BiFeO₃–BaTiO₃ superlattices—

Noguchi

Matsuo

2022

Density functional theory calculations are conducted for tetragonal BiFeO3–BaTiO3 superlattices to investigate the influence of electronic structures on ferroelectric spontaneous polarization (Ps). When the number of the perovskite unit cell in one layer (N) is decreased below 10, the Ps starts to decrease from the volume-averaged one of 50.9 C/cm2 and eventually becomes half at N = 1. In the BiFeO3 cell (N = ∞) with a large Ps (73.3 C/cm2), a Bi-O covalent bond arising from a Bi_6p-O_2p orbital interaction is extended in an -O-Bi-O- network, and stereo-chemical lone-pair electrons of Bi are accommodated in the opposite direction of the c axis. In the superlattice with N = 1, the -O-Bi-O- bonding is interrupted by Ba and then the Bi-O bond becomes ionic. We show that the large Ps of the BiFeO3 cell originates from the Bi_6p-O_2p mixing superimposed on the stereo-chemical nature of lone-pair electrons of Bi.