Ferroelectric Properties and Domain Structures of (Bi&lt;sub&gt;0.5&lt;/sub&gt;K&lt;sub&gt;0.5&lt;/sub&gt;)TiO&lt;sub&gt;3&lt;/sub&gt;-BiFeO&lt;sub&gt;3&lt;/sub&gt; Ceramics

Matsuo, Hideo; Kitanaka, Yuuki; Noguchi, Yuji; Miyayama, Masaru; Ozaki, Tomoatsu; Mori, Shigeo; Torii, Shuki; Kamiyama, Takashi

doi:10.14723/tmrsj.36.285

Cited by 5 publications

(2 citation statements)

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“…Bismuth potassium/sodium titanates, Bi 0.5 K 0.5 TiO 3 (BKT) and Bi 0.5 Na 0.5 TiO 3 (BNT), are lead-free piezoelectric perovskites − which are important end members in solid solutions which can replace environmentally hazardous Pb(Zr,Ti)O 3 (PZT). , Bismuth based PZT replacements also possess 6s lone pairs which play an important role for the spontaneous polarization and structural distortion. , BKT was first reported in 1961, and solid solutions based on BKT have shown promising piezoelectric and ferroelectric properties. − Compared to rhombohedral R 3 c BNT, BKT is comparatively less studied, partly due to challenges with sintering dense polycrystals, and to pole these materials. ,− The structure of ferroelectric BKT is tetragonal P 4 mm ( a = 3.933 Å, c = 3.975 Å, c / a = 1.01) below the second-phase transition temperature ,,− T 2 of 270–310 °C, pseudocubic above T 2 , and finally paraelectric cubic Pm 3̅ m above the Curie temperature T C of 370–410 °C. ,,,, …”

Section: Introductionmentioning

confidence: 99%

Structural Disorder and Coherence across the Phase Transitions of Lead-Free Piezoelectric Bi_0.5K_0.5TiO₃

et al. 2018

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Relaxor ferroelectrics exhibit superior properties for converting mechanical energy into electrical, and vice versa, but the structural disorder hampers an understanding of structureproperty relationships, and impedes rational design of new, lead-free materials. Bi0.5K0.5TiO3 (BKT) is a prototypical lead-free relaxor ferroelectric, but the microscopic origins of polarization, nature of the ferroelectric transition (TC) and structural changes across the tetragonal to pseudo-cubic transition (T2) are poorly understood. Here the local and intermediate structure of BKT is studied from room temperature to above TC by pair distribution functions (PDF) from synchrotron X-ray total scattering experiments and complemented by ab initio molecular dynamics (AIMD) simulations. The local structure varies smoothly across T2 as well as TC, in contrast to the abrupt changes at TC inferred from conventional diffraction.Ferroelectric distortions are larger on the local scale than in the average structure, with polar Ti 4+ displacements prevailing above TC. We find that local polar regions partly cancel each other below TC, while completely averaging out above, implying that BKT goes through a transition from partial to complete disorder across TC.

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Section: Introductionmentioning

confidence: 99%

Structural Disorder and Coherence across the Phase Transitions of Lead-Free Piezoelectric Bi_0.5K_0.5TiO₃

et al. 2018

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“…Bismuth-based solid solutions like (1-x)Bi0.5K0.5TiO3-xBiFeO3 (BKT-xBFO) [1][2][3][4][5][6][7][8][9] are being developed as alternatives to lead-containing and environmentally hazardous PZT-based (PbZr1-xTixO3) materials [10,11] for piezoelectric and electromechanical applications. BiFeO3 (BFO) is multiferroic with high Néel (TN) and Curie (TC) temperatures of 370 °C and 830 °C, respectively, and the rhombohedral R3c structure [12][13][14][15] displays a large spontaneous polarization, Ps, of ~90μC/cm 2 at room temperature [16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Local structural coupling of A- and B-site disorder in perovskite bismuth-based piezoelectrics

et al. 2019

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The local and average structure of (1-x)Bi0.5K0.5TiO3-xBiFeO3 (BKT-xBFO, x = 0.25 and 0.5) solid solutions are studied by synchrotron X-ray total scattering from ambient to 773 K. Pair distribution functions (PDFs) demonstrate that disordered BKT-0.25BFO and BKT-0.5BFOshow the same structural coherence length of ~16 Å as pure Bi0.5K0.5TiO3, while their average structures are pseudocubic at all temperatures. Complementary density functional theory (DFT) calculations suggest distinctly different local structural distortions in BKT-0.25BFO and BKT-0.5BFO with random cations distribution on both A-and B-lattice. Based on the experimental and theoretical analysis, we propose that the optimal piezoelectric properties found at the structural phase boundary composition of x = 0.25 originate from tetragonal and rhombohedral polar nanoregions (PNRs) in an on average pseudocubic matrix. In contrast, for x = 0.5 there are only pseudorhombohedral polar distortions in a pseudocubic matrix phase.

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Emerging Halide Perovskite Ferroelectrics

et al. 2023

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lasers, [5] single-mode lasers, [6] continuouswave lasers, [7] polariton lasers, [8] and laser arrays. [9] Halide perovskites have also been widely studied in photocatalytic organic reaction, [10] photocatalytic CO 2 reduction, [11] and photocatalytic hydrogen evolution. [12] Due to their broad technological importance, halide perovskites have become the focus of current research.Recently, ferroelectricity has been detected in halide perovskites and quickly attracted widespread interest. [13] Ferroelectricity is a characteristic of spontaneous polarization in certain materials, which can be reversed by applying an external electric field. The discovery of ferroelectricity can be traced back to 1920 [14] (Figure 1a), when Valasek measured the polarization of Rochelle Salt as a function of the applied electric field. Perovskite ferroelectric first appeared on the scene in the early 1940s [15] (Figure 1b). Up to now, perovskite oxides (e.g., BaTiO 3 , [16] PbZr x Ti 1−x O 3 , [17] Bi 4−x La x Ti 3 O 12 , [18] LiNbO 3 , [19] and LiTaO 3 [20] ) as main ferroelectric materials have been widely applied to supercapacitors, [21] memories, [22] sensors, [23] and actuators, [24] which play key roles in modern technologies benefiting human lives. Nevertheless, the fatal weakness of brittleness for most perovskite oxides limits their application in flexible devices. [25] Therefore, perovskite oxide ferroelectrics are losing competitiveness in future technologies pursuing device miniaturization and flexibility. The emergence of halide perovskite ferroelectrics that feature the natural advantages of structural softness and lightweight has thus opened a new chapter in ferroelectric research.Since ferroelectricity was recognized in halide perovskites, the research activities have mainly focused on designing novel halide perovskite ferroelectrics. [35] In the past few years, the collective efforts from interdisciplinary communities have made available a collection of halide perovskite ferroelectrics with distinct compositions and structures (Figure 1c-i), such as 0D (NMP) 3 Sb 2 Cl 9 (NMP = N-methylpyrrolidinium) , [31] 1D (3-pyrrolinium)CdCl 3 , [28] 2D (BEA) 2 PbCl 4 (BEA = benzylammonium), [29] and 3D organometal (AP)RbBr 3 (AP = 3-ammoniopyrrolidinium). [30] Preliminary experiments have revealed the great promise of these materials for applications in ferroelectric photovoltaics, [36] self-powered photodetection, [37] and X-ray detection. [38] On a separate note, the development of halide perovskite ferroelectrics also raises important issues in the mechanistic investigation of halide perovskite in optoelectronics. For example, the possible existence of ferroelectricity was proposed to explain the superior optoelectronic Halide perovskites have gained tremendous attention in the past decade owing to their excellent properties in optoelectronics. Recently, a fascinating property, ferroelectricity, has been discovered in halide perovskites and quickly attracted widespread interest. Compared with traditional perovskite oxide fe...

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Ferroelectric Properties and Domain Structures of (Bi<sub>0.5</sub>K<sub>0.5</sub>)TiO<sub>3</sub>-BiFeO<sub>3</sub> Ceramics

Cited by 5 publications

References 14 publications

Structural Disorder and Coherence across the Phase Transitions of Lead-Free Piezoelectric Bi_0.5K_0.5TiO₃

Structural Disorder and Coherence across the Phase Transitions of Lead-Free Piezoelectric Bi_0.5K_0.5TiO₃

Local structural coupling of A- and B-site disorder in perovskite bismuth-based piezoelectrics

Emerging Halide Perovskite Ferroelectrics

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Ferroelectric Properties and Domain Structures of (Bi<sub>0.5</sub>K<sub>0.5</sub>)TiO<sub>3</sub>-BiFeO<sub>3</sub> Ceramics

Cited by 5 publications

References 14 publications

Structural Disorder and Coherence across the Phase Transitions of Lead-Free Piezoelectric Bi0.5K0.5TiO3

Structural Disorder and Coherence across the Phase Transitions of Lead-Free Piezoelectric Bi0.5K0.5TiO3

Local structural coupling of A- and B-site disorder in perovskite bismuth-based piezoelectrics

Emerging Halide Perovskite Ferroelectrics

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Structural Disorder and Coherence across the Phase Transitions of Lead-Free Piezoelectric Bi_0.5K_0.5TiO₃

Structural Disorder and Coherence across the Phase Transitions of Lead-Free Piezoelectric Bi_0.5K_0.5TiO₃