Erratum: Phase transitions and phase diagram of the ferroelectric perovskite (Na<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow /><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Bi<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow /><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>)<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="in

Cordero, F.; Craciun, F.; Trequattrini, F.; Mercadelli, Elisa; Galassi, Carmen

doi:10.1103/physrevb.83.059902

Cited by 38 publications

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“…Here, the {110} and {111} peaks are observed to narrow with increasing temperature (Figure 1a) with both peaks reach a minimum width in the range 300-320 °C, clearly indicating that this is a phase transition, in agreement with other studies. [5][6][7] Whilst the equivalent peak widths from solid-state NBT also show this phase transition (Figure 1b), the overall change in peak widths is significantly smaller than for hydrothermal NBT, which therefore evidences this particular transition much more clearly than has been seen before. The increase in the {110} peak width above this phase transition is consistent with emerging tetragonal symmetry, indicating 300 (10) °C as the pseudo-rhombohedral-tetragonal phase transition temperature, in agreement with optical birefringence measurements.…”

Section: Textmentioning

confidence: 70%

“…4 However, the deviation from rhombohedral symmetry is very small and the room-temperature structure may be considered pseudo-rhombohedral. On heating, a phase transition to tetragonal symmetry is known to exist, but has been reported to take place over a range of temperatures: 278-291 °C, 5 240-270 °C 6 and 300-320 °C. 7 At the boundary between pseudorhombohedral and tetragonal structures, some studies 8 have shown the existence of a two-phase region, while others 9 have proposed the presence of an intermediate phase.…”

Section: Textmentioning

confidence: 99%

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Inference of oxygen vacancies in hydrothermal Na0.5Bi0.5TiO3

O'Brien

Woodward

Sardar

et al. 2012

Applied Physics Letters

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A high-resolution x-ray powder diffraction study has been made of pseudo-rhombohedral and tetragonal phases in Na 0.5 Bi 0.5 TiO 3 (NBT), produced via hydrothermal and conventional solid-state methods. Hydrothermal NBT exhibits significantly greater structural distortion at room temperature than solid-state NBT. Peak widths and superstructure peak intensities show a phase transition at ~ 305 °C, with trends suggesting that the structure tends towards cubic symmetry at this temperature. Structural refinements indicate that the transition occurs via a phase coexistence region with no clear intermediate phase. Piezoelectric data show evidence of polarisation pinning in hydrothermal NBT, interpreted as a high proportion of oxygen vacancies. TextSodium bismuth titanate, Na 0.5 Bi 0.5 TiO 3 (NBT) is a widely-studied relaxor perovskite of potential use as a lead-free piezoelectric, particularly as the end-member of a range of solid solutions including NBT-BaTiO 3 and NBT-K 0.5 Bi 0.5 TiO 3 . 1 At room temperature, the structure has long been designated as rhombohedral R3c, 2 although recent studies have suggested monoclinic Cc symmetry for both single crystals 3 and sintered ceramics. 4 However, the deviation from rhombohedral symmetry is very small and the room-temperature structure may be considered pseudo-rhombohedral. On heating, a phase transition to tetragonal symmetry is known to exist, but has been reported to take place over a range of temperatures: 278-291 °C, 5 240-270 °C 6 and 300-320 °C. 7 At the boundary between pseudorhombohedral and tetragonal structures, some studies 8 have shown the existence of a two-phase region, while others 9 have proposed the presence of an intermediate phase. The phase transition to the cubic structure takes place at 500-550 °C 8,10 although some studies 11,12 refer to the pseudorhombohedral -tetragonal transition as the ferroelectric Curie temperature.In this study, the structures, phase transitions and piezoelectric properties of polycrystalline NBT produced by a low-temperature hydrothermal method are investigated and compared with those of a sample made by conventional solid-state synthesis. This study is motivated by the observation over many years that the structures and physical properties of NBT can vary significantly depending on the synthetic method adopted and the thermal history of the material. 4 Limited previous studies of hydrothermal NBT have been undertaken 12,13 but the structural phase transitions and piezoelectric properties of hydrothermal NBT have not been investigated before.NBT was synthesised in an autoclave with a polytetrafluoroethane liner using a 1:4 molar ratio of Bi 2 O 3 :TiO 2 (99.9%, Janssen Chimica, -Bi 2 O 3 , and >98%, BDH, anatase polymorph, respectively). Typically ~4 g Bi 2 O 3 and the corresponding amount of TiO 2 were reacted in a 125 ml autoclave. 60 ml of 10 M NaOH solution was added and the suspension stirred for 2 hours. The autoclave was placed in an oven at 240 °C and left at autogenous pressure for 5 days before cooling. ...

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Section: Textmentioning

confidence: 70%

Section: Textmentioning

confidence: 99%

Inference of oxygen vacancies in hydrothermal Na0.5Bi0.5TiO3

O'Brien

Woodward

Sardar

et al. 2012

Applied Physics Letters

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“…For BNT-based piezoceramics, T c is also frequently reported in the literature; although, because of the relaxor behavior of these materials, the temperature of maximum permittivity T m cannot be considered a Curie point. 10,11 Moreover, the degradation of piezoelectric properties often takes place around an additional transition temperature referred to as depolarization temperature T d , which is found well below T m . In BNT-based systems, there is a weakly polar intermediate phase, 12 which occurs between the T d and T m .…”

Section: Introductionmentioning

confidence: 99%

Determination of depolarization temperature of (Bi1/2Na1/2)TiO3-based lead-free piezoceramics

Anton¹,

Jo²,

Damjanović³

et al. 2011

Journal of Applied Physics

282

168

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The depolarization temperature T d of piezoelectric materials is an important figure of merit for their application at elevated temperatures. Until now, there are several methods proposed in the literature to determine the depolarization temperature of piezoelectrics, which are based on different physical origins. Their validity and inter-correlation have not been clearly manifested. This paper applies the definition of depolarization temperature as the temperature of the steepest decrease of remanent polarization and evaluates currently used methods, both in terms of this definition and practical applicability. For the investigations, the lead-free piezoceramics (1-y)(Bi 1/2 Na 1/2 TiO 3 -xBi 1/2 K 1/2 TiO 3 )ÀyK 0.5 Na 0.5 NbO 3 in a wide compositional range were chosen. Results were then compared to those for BaTiO 3 and a commercial Pb(Zr,Ti)O 3 -based material as references. Thermally stimulated depolarization current and in situ temperature-dependent piezoelectric coefficient d 33 are recommended to determine T d according to the proposed definition. Methods based on inflection point of the real part of permittivity or the peak in dielectric loss give consistently higher temperature values.

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“…2 Furthermore, recent investigations of Na 1/2 Bi 1/2 TiO 3 -xat.%BaTiO 3 (NBT-x%BT) have revealed giant strain and longitudinal piezoelectric constants as high as d 33 ¼ 500 pC/N for compositions near a morphotropic phase boundary (MPB) around x ¼ 5.5-6.5. [3][4][5][6][7][8][9][10][11][12][13] In spite of a non-rhombohedral average structure model for NBT at room temperature was supported by highresolution single-crystal x ray diffraction, 14 it is still widely accepted that NBT undergoes a phase transformational sequence of paraelectric cubic (C) ! paraelectric tetragonal (T) !…”

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confidence: 99%

“…22 Support of these observations has also been reported by anelastic measurements. 6 High resolution transmission electron microscopy (HRTEM) has shown that the lattice is partially incoherent across the boundaries between polar nano-regions. 25 Formation of planar defects along the domain boundaries may help relax the elastic energy in this geometrically frustrated condition.…”

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confidence: 99%

The influence of Mn substitution on the local structure of Na0.5Bi0.5TiO3 crystals: Increased ferroelectric ordering and coexisting octahedral tilts

Yao

et al. 2012

Journal of Applied Physics

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The ferroelectric domain structure of pure Na 1/2 Bi 1/2 TiO 3 (NBT) and 1 at.% Mn-doped NBT (Mn-NBT) crystals was investigated by piezoresponse force microscopy. The correlation length of the polar regions was found to increase upon Mn substitution. High resolution transmission electron microscopy revealed that the coherency of the lattice across the domain boundaries between polar regions was also enhanced. Selected area electron diffraction showed that Mn favored coexisting 1/2 (ooo) and 1/2 (ooe) oxygen octahedral tiltings, over only 1/2 (ooo) for pure NBT. V C 2012 American Institute of Physics. [http://dx

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Erratum: Phase transitions and phase diagram of the ferroelectric perovskite (Na0.5Bi0.5)
F. Cordero¹,
F. Craciun²,
F. Trequattrini³
et al.

Abstract: In the legend in the upper right-hand corner of Fig. 9, the label T 3 for the dielectric measurements (downward pointing triangle) should be replaced with T 2 . The rest of the paper is unaffected by this mistake.

Cited by 38 publications

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Inference of oxygen vacancies in hydrothermal Na0.5Bi0.5TiO3

Inference of oxygen vacancies in hydrothermal Na0.5Bi0.5TiO3

Determination of depolarization temperature of (Bi1/2Na1/2)TiO3-based lead-free piezoceramics

The influence of Mn substitution on the local structure of Na0.5Bi0.5TiO3 crystals: Increased ferroelectric ordering and coexisting octahedral tilts

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Erratum: Phase transitions and phase diagram of the ferroelectric perovskite (Na0.5Bi0.5)F. Cordero1, F. Craciun2, F. Trequattrini3 et al.

Abstract: In the legend in the upper right-hand corner of Fig. 9, the label T 3 for the dielectric measurements (downward pointing triangle) should be replaced with T 2 . The rest of the paper is unaffected by this mistake.

Cited by 38 publications

References 0 publications

Inference of oxygen vacancies in hydrothermal Na0.5Bi0.5TiO3

Inference of oxygen vacancies in hydrothermal Na0.5Bi0.5TiO3

Determination of depolarization temperature of (Bi1/2Na1/2)TiO3-based lead-free piezoceramics

The influence of Mn substitution on the local structure of Na0.5Bi0.5TiO3 crystals: Increased ferroelectric ordering and coexisting octahedral tilts

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Erratum: Phase transitions and phase diagram of the ferroelectric perovskite (Na0.5Bi0.5)
F. Cordero¹,
F. Craciun²,
F. Trequattrini³
et al.