Domain structure and polarization properties of lanthanum-substituted bismuth titanate single crystals

Soga, Masayuki; Noguchi, Yuji; Miyayama, Masaru; Okino, Hirotake; Yamamoto, Takashi

doi:10.1063/1.1638631

Cited by 62 publications

(55 citation statements)

References 20 publications

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“…It is apparent that decreasing grain size drastically decreases the width of striped 90 domains, thereby increasing the domain-wall density in each grain. The width of the 90 domains have been determined to be 8.5 lm in millimeter-sized single crystals, [17] which decreases to below 1 lm in individual grains with a width of~5 lm, as revealed in Figure 4.…”

Section: ±1mentioning

confidence: 99%

Effective Grain Alignment in Bi₄Ti₃O₁₂ Ceramics by Superplastic‐Deformation‐Induced Directional Dynamic Ripening

Shen¹,

Liu

Grîns

et al. 2005

Advanced Materials

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A certain extent of orientation of the Col hd mesophase can be inferred from Figure 1G in the temperature interval corresponding to the very end of melting. Since the width of the mesophase peak significantly decreases at these temperatures, we suggest that larger and more perfectly ordered domains are being formed. Such domains could partially preserve their orientation upon a short passage in the isotropic melt.[39] Although the studied molecule does not contain any chiral centers, the helicity in the crystalline phase is believed to be caused by a slight non-planarity of the molecular core (out-of-plane tilt of the phenyl groups) inducing rotational shift of the neighboring molecules in the column Ceramics are polycrystalline materials that often exhibit isotropic physical properties even when the tiny crystal grains that constitute the dense compact are anisotropic. This is due to the fact that the grains are usually randomly oriented with respect to their crystallographic orientation. Efforts have been made in the past to align the anisotropic grains in ceramics in order to produce anisotropic ceramics that mimic the properties of anisotropic single crystals, i.e., to produce textured or grain-oriented microstructures. Two strategies to achieve such anisotropic microstructures have been examined so far, namely: i) preparation of powders, preferably with needle or platelet morphologies, aligned via a shear-flow process, followed by pressureless sintering and/or hot-forming for extended times at high temperatures in order to allow the growth of aligned grains according to the Ostwald ripening mechanism; [1,2] and ii) in order to improve the grain alignment even further, addition of a small part of well-developed, large (2±5 lm) needles or platelets as grain-growth templates. [3,4] With these established processing concepts, in order to ensure a high degree of grain alignment, an increase in the initial size of the particles is a prerequisite. However, this slows down both the speed of densification and grain alignment, implying an unfavorable prolongation of the processing time.The work reported here opens a new direction by starting with nanopowders instead of micrometer-sized powders. It was initially motivated by the two recent findings that i) rapid COMMUNICATIONS 676

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Section: ±1mentioning

confidence: 99%

Effective Grain Alignment in Bi₄Ti₃O₁₂ Ceramics by Superplastic‐Deformation‐Induced Directional Dynamic Ripening

Shen¹,

Liu

Grîns

et al. 2005

Advanced Materials

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“…Although domain-structure observations of BiT-based films have been conducted, [28,29] the detailed domain structures of 180°DWs in addition to the 90°DWs have not been clarified yet. Recently, Soga et al [30] have reported the 90°domain structures of BiT crystals in the a-b plane using PFM. The domain analysis by using PFM enables us to obtain the information of P s vector of each domain with a high spatial resolution.…”

mentioning

confidence: 99%

3D Domain Structure in Bi₄Ti₃O₁₂ Crystals Observed by Using Piezoresponse Force Microscopy

2007

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The control of bistable polarization states in ferroelectrics is the underlying basis of their applications to nonvolatile memories, piezoelectric devices, and micro-electromechanical systems. The switching of the polarization states by applying an electric field is governed by the dynamics of ferroelectric domains in which spontaneous polarization (P s ) is aligned in a single direction. The polarization switching is established by nucleation of new domains followed by the movement of domain walls (DWs). The crystallography and thermodynamics of the domain structures have been extensively studied and well understood not only in bulk systems [1,2] but also in constrained films. [3,4] Recently, in perovskite ferroelectrics such as PbTiO 3 and BaTiO 3 , 90°DWs have been reported to strongly interact with charged defects such as oxygen vacancies. [5][6][7][8][9][10][11] The interaction between DWs and defects leads to a viscous movement of the DWs, and the domain structure inside ferroelectric crystals is expected to be different from that predicted by the existing theory without taking the influence of defects into account. Here, we report on the 3D domain structure in ferroelectric Bi 4 Ti 3 O 12 crystals investigated by using piezoresponse force microscopy (PFM). Energetically favorable 90°D Ws with faceted structure are established on the surface along the a-b plane, while the 90°DWs have complicated and curved surfaces along the c-axis inside the crystals. The curved 90°domain structure can be explained by the strong interaction between the local electric field near the 90°DWs and oxygen vacancies.Ferroelectric Bi 4 Ti 3 O 12 (BiT) has great potential for various applications such as nonvolatile memories and leadfree piezoelectric devices, because BiT shows a high Curie temperature (T C ) of 675°C and a large P s of more than 50 lC cm -2 . [12][13][14][15] The crystal structure of BiT is described as an alternate stacking of Bi 2 O 2 layers and perovskite Bi 2 Ti 3 O 10 layers along the c-axis. Despite having the large P s , BiT has been reported to exhibit a polarization fatigue as well as a small remanent polarization (P r ). Numerous studies [16][17][18][19][20][21][22] have been conducted to overcome these drawbacks by element substitution and/or doping. It is widely recognized that the polarization fatigue and small P r originate from domain pinning, that is, a decrease in switchable domains by applying an electric field, which is caused by the interaction between DWs and defects such as oxygen vacancies. [8][9][10][11] It is essential to understand the domain structures and the interaction between the DWs and oxygen vacancies for improving the polarization properties of BiT-based devices. Recent experimental observations have revealed that 90°DWs in SrBi 2 Nb 2 O 9[23] are irregular and highly curved due to their extremely low ferroelastic distortion of less than 0.01 %. Phase-field simulations [24] have verified that the curved 90°DWs are a result of the dominant contribution of isotropic DW energy compa...

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“…The theoretical density of BLTBi 3.25 La 0.75 Ti 3 O 12 is 7.43 gcm 3 , which has been determined by neutron powder diffraction analysis. 28 In these experiments, as-synthesized FCM powder without any dispersed processing such as ball milling and any calcination was pressed into pellet, and then sintered at various temperatures. The holding time for the sintering was fixed at 2 h. For the conventional method, the sintering below 1100c C led to porous ceramics with a relative density less than 50ಚ.…”

Section: Flash Creation Methods and Experimentsmentioning

confidence: 99%

High-Quality Lead-Free Ferroelectric Ceramics Prepared from the Flash-Creation-Method-Derived Nanopowder

Watanabe¹,

Fukui²,

Nogi

et al. 2006

J. Ceram. Soc. Japan

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Paper péÉÅá~ä fëëìÉ Äó dìÉëí bÇáíçêëW kçîÉä j~íÉêá~äë aÉëáÖå~åÇ mêçÅÉëëáåÖ Äó bñíÉêå~ä åÇ fåíÉêå~ä oÉ~Åíáçå cáÉäÇë eáÖÜnì~äáíó iÉ~ÇcêÉÉ cÉêêçÉäÉÅíêáÅ`Éê~ãáÅë mêÉé~êÉÇ Ñêçã íÜÉ cä~ëÜ`êÉ~íáçåjÉíÜçÇaÉêáîÉÇ k~åçéçïÇÉê We report high-quality and high-density Bi 3.25 La 0.75 Ti 3 O 12 ceramics prepared by sintering at a low temperature of 900c C from the nanosized powder with a diameter around 100 nm synthesized by the flash creation method. The densification at 900c C, which was 300c C lower sintering temperature compared with conventional solid-state reaction, enables us to obtain the ceramics showing a remanent polarization of 14.5 mCcm 2 , a coercive field of 50 kVcm and a leakage current of ࣽ10 ࢬ9 Acm 2 . The superior properties are indicated to originate from lower defect concentration achieved by the low temperature sintering.

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Domain structure and polarization properties of lanthanum-substituted bismuth titanate single crystals

Cited by 62 publications

References 20 publications

Effective Grain Alignment in Bi₄Ti₃O₁₂ Ceramics by Superplastic‐Deformation‐Induced Directional Dynamic Ripening

Effective Grain Alignment in Bi₄Ti₃O₁₂ Ceramics by Superplastic‐Deformation‐Induced Directional Dynamic Ripening

3D Domain Structure in Bi₄Ti₃O₁₂ Crystals Observed by Using Piezoresponse Force Microscopy

High-Quality Lead-Free Ferroelectric Ceramics Prepared from the Flash-Creation-Method-Derived Nanopowder

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Domain structure and polarization properties of lanthanum-substituted bismuth titanate single crystals

Cited by 62 publications

References 20 publications

Effective Grain Alignment in Bi4Ti3O12 Ceramics by Superplastic‐Deformation‐Induced Directional Dynamic Ripening

Effective Grain Alignment in Bi4Ti3O12 Ceramics by Superplastic‐Deformation‐Induced Directional Dynamic Ripening

3D Domain Structure in Bi4Ti3O12 Crystals Observed by Using Piezoresponse Force Microscopy

High-Quality Lead-Free Ferroelectric Ceramics Prepared from the Flash-Creation-Method-Derived Nanopowder

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Effective Grain Alignment in Bi₄Ti₃O₁₂ Ceramics by Superplastic‐Deformation‐Induced Directional Dynamic Ripening

Effective Grain Alignment in Bi₄Ti₃O₁₂ Ceramics by Superplastic‐Deformation‐Induced Directional Dynamic Ripening

3D Domain Structure in Bi₄Ti₃O₁₂ Crystals Observed by Using Piezoresponse Force Microscopy