Electric-field-induced and spontaneous relaxor-ferroelectric phase transitions in (Na1/2Bi1/2)1 − xBaxTiO3

Craciun, F.; Galassi, Carmen; Bı̂rjega, R.

doi:10.1063/1.4770326

Cited by 91 publications

(39 citation statements)

References 29 publications

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“…It indicates that unpoled BNT-6BT is polar at a local scale, despite being macroscopically cubic. The fact that this polar phase is hardly detected macroscopically [21,23,24,35] strongly supports its nanometric character. Moreover, it unveils NMR as a suitable tool for characterizing this class of materials.…”

mentioning

confidence: 79%

“…As BNT-6BT, these compositions also exhibit relaxor features in the unpoled state [35,37], implying that the relaxor behavior is attributed to the observed cubic phase. This relation is further supported by the fact that BNT-15BT, a composition which does not display marked relaxor features, did not exhibit a considerable amount of a cubic phase.…”

Section: Fig 1 (Color Online) Comparison Between (A)-(c) Measured Amentioning

confidence: 97%

“…Solid solutions of composition (100 − x)(Bi 1/2 Na 1/2 )TiO 3 -xBaTiO 3 (BNT-xBT) were chosen for this study. The phase diagram of BNT-xBT [20] encompasses both variations in relaxor character and crystal structure with barium content [3,12,35,36]. Specifically, a rhombohedral region (barium content, x < 5), such as BNT-1BT and BNT-4BT, present relaxor features to some extent [35,37].…”

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confidence: 99%

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Nanoscale phase quantification in lead-free(Bi1/2Na1/2)TiO3−BaTiO
Groszewicz
¹
,
Breitzke
²
,
Dittmer
³

et al. 2014
Phys. Rev. B
58
1
34
0
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We address the unsolved question on the structure of relaxor ferroelectrics at the atomic level by characterizing lead-free piezoceramic solid solutions (100 − x)(Bi 1/2 Na 1/2 )TiO 3 -xBaTiO 3 (BNT-xBT) (for x = 1, 4, 6, and 15). Based on the relative intensity between spectral components in quadrupolar perturbed 23 Na nuclear magnetic resonance, we present direct evidence of the coexistence of cubic and polar local symmetries in these relaxor ferroelectrics. In addition, we demonstrate how the cubic phase vanishes whenever a ferroelectric state is induced, either by field cooling or changing the dopant amount, supporting the relation between this cubic phase and the relaxor state. Relaxor ferroelectrics have been intensively studied in the past 30 years because of their intriguing structural and dielectric features [1][2][3]. Despite that, the nature of their ground state remains an open question [4][5][6][7][8][9][10][11][12]. Several models have been proposed to describe this puzzling class of materials [1,[5][6][7][8]13], two of which are mainly concerned with the structure of the ground state of relaxors [4].The random field (RF) model proposes a single-phase structure broken up into ferroelectric nanodomains. These nanodomains are kept small under the constraint of quenched random electric fields which originate from chemical disorder [7,14]. The other model introduced the concept of "polar nanoregions" (PNRs) [13]. When relaxors are cooled below the Burns temperature, small and randomly oriented polarized regions (PNRs) appear within the otherwise nonpolar crystal structure. Upon further cooling, PNRs grow in size and number [11], but their percolation is prevented by structural disorder and random electric fields [8,10,12]. This behavior would imply the coexistence of PNRs and a nonpolar matrix, in contrast to the single-phase structure proposed by the RF model.An induced ferroelectric state can be established in relaxors when a strong electric field is applied. This state features macroscopic polarization and breaking of the cubic average symmetry [5,11,[15][16][17]. While the RF model suggests that this transformation and the formation of macroscopic ferroelectric domains are caused only by reorientation of previously nanometric ferroelectric domains, an additional mechanism is required when PNRs are considered. In that case, a long-range ferroelectric state can only be established if the nonpolar matrix becomes polarized, being incorporated by the growing PNRs.Two questions are raised by contrasting these two models: (1) Does the microscopic structure of relaxor ferroelectrics consist only of ferroelectric nanodomains or do regions of lower local symmetry (PNRs) coexist with a nonpolar matrix of * gerd.buntkowsky@chemie.tu-darmstadt.de † roedel@ceramics.tu-darmstadt.de undistorted structure? (2) How does the microscopic structure of relaxors evolve upon electric poling?In spite of their relevance, such questions have remained unsolved largely because the structural characterization of relaxors is a c...

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mentioning

confidence: 79%

Section: Fig 1 (Color Online) Comparison Between (A)-(c) Measured Amentioning

confidence: 97%

mentioning

confidence: 99%

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Nanoscale phase quantification in lead-free(Bi1/2Na1/2)TiO3−BaTiO
Groszewicz
¹
,
Breitzke
²
,
Dittmer
³

et al. 2014
Phys. Rev. B
58
1
34
0
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“…This may be linked to the microstructural change due to the change of the stoichiometric state of this composition. Composition B has a bigger c/a ratio than all other compositions ( Table 1), indicating that Composition B has more tetragonality in its structure than all other compositions [13,43,44,46,47]. Importantly, at RT, the p values for nonstoichiometry compositions are higher than that of PZT and other lead-free compositions (Table 2) [7,19,27,32].…”

Section: Effects Of Nonstoichiometry Composition On Pyroelectric Propmentioning

confidence: 92%

Large pyroelectric properties at reduced depolarization temperature in A-site nonstoichiometry composition of lead-free 0.94Na x Bi y TiO3–0.06Ba z TiO3 ceramics

2017

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Nonstoichiometry lead-free 0.94Na x Bi y TiO 3 -0.06Ba z TiO 3 (N x B y T-0.06B z T) (from x = y = 0.5, z = 1.00 to x = 0.5, y = 0.534, z = 1.02) ceramic compositions were prepared by a conventional solid-state route. XRD shows that the compositions are at a morphotropic phase boundary where rhombohedral and tetragonal phases coexist. The depolarization temperature (T d ) can be lowered by modifying x, y and z. The pyroelectric coefficient (p) of nonstoichiometry N x B y T-0.06B z T compositions is greatly increased, compared with stoichiometry NBT-0.06BT composition, from 3.15 9 10 -4 C m -2°C-1 at room temperature (RT) and 23.9 9 10 -4 C m -10 m v -1 , 0.39 9 10 -10 m 2 C -1 and 138.7 9 10 -6 Pa -1/2 , respectively, at T d . The same composition also presents F C values which are *2.58 and *2.86 (910 -9 C cm -2°C-1 ) at RT at 100 and 1000 (Hz). N 0.5 B 0.534 T-0.06BT and N 0.5 B 0.534 T-0.06B 1.02 T compositions show a large p values at a wide temperature range. The enhanced pyroelectric properties make nonstoichiometry N 0.52 B 0.52 T-0.06BT composition a promising candidate for pyroelectric and other applications at wide temperatures range.

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“…Lead-free ceramics with composition at the solid solution system of (1 − x)(Bi 0.5 Na 0.5 )TiO 3 -xBaTiO 3 (BNBT100x) with x = 0.06 have been widely studied in recent years due to their complex crystal structure, exhibiting a field induced phase transition at the nano-scale between short-range ordered and ferroelectric, long-range ordered, polar states [1,2]. The thermal depolarization accompanied by the inhibition of the piezoelectric activity [1] has a multiple origin [3,4].…”

Section: Introductionmentioning

confidence: 99%

Electromechanical Anisotropy at the Ferroelectric to Relaxor Transition of (Bi0.5Na0.5)0.94Ba0.06TiO3 Ceramics from the Thermal Evolution of Resonance Curves

et al. 2018

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(Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 TiO 3 dense ceramics were obtained from autocombustion sol-gel synthesized nanopowders and sintered at 1050 • C for 1-2 h for the study of the electromechanical anisotropy. Measurement of the complex impedance spectrum was carried out on thin ceramic disks, thickness-poled, as a function of the temperature from 16 • C up to the vanishing of the electromechanical resonances at the ferroelectric to relaxor transition near 100 • C. The spectrum comprises the fundamental radial extensional mode and three overtones of this, together with the fundamental thickness extensional mode, coupled with other complex modes. Thermal evolution of the spectrum shows anisotropic behavior. Piezoelectric, elastic, and dielectric material coefficients, including all losses, were determined from iterative analysis of the complex impedance curves at the planar, thickness, and shear virtually monomodal resonances of disks and shear plates, thickness-poled. d 33 was measured quasi-statically at 100 Hz. This set of data was used as the initial condition for the optimization of the numerical calculation by finite elements of the full spectrum of the disk, from 100 kHz to 1.9 MHz, to determine the thermal evolution of the material coefficients. An appropriate measurement strategy to study electromechanical anisotropy of piezoelectric ceramics has been developed.

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Electric-field-induced and spontaneous relaxor-ferroelectric phase transitions in (Na1/2Bi1/2)1 − xBaxTiO3

Cited by 91 publications

References 29 publications

Nanoscale phase quantification in lead-free(Bi1/2Na1/2)TiO3−BaTiO
Groszewicz
¹
,
Breitzke
²
,
Dittmer
³

et al. 2014
Phys. Rev. B
58
1
34
0
View full text Add to dashboard Cite

Nanoscale phase quantification in lead-free(Bi1/2Na1/2)TiO3−BaTiO
Groszewicz
¹
,
Breitzke
²
,
Dittmer
³

et al. 2014
Phys. Rev. B
58
1
34
0
View full text Add to dashboard Cite

Large pyroelectric properties at reduced depolarization temperature in A-site nonstoichiometry composition of lead-free 0.94Na x Bi y TiO3–0.06Ba z TiO3 ceramics

Electromechanical Anisotropy at the Ferroelectric to Relaxor Transition of (Bi0.5Na0.5)0.94Ba0.06TiO3 Ceramics from the Thermal Evolution of Resonance Curves

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Electric-field-induced and spontaneous relaxor-ferroelectric phase transitions in (Na1/2Bi1/2)1 − xBaxTiO3

Cited by 91 publications

References 29 publications

Nanoscale phase quantification in lead-free(Bi1/2Na1/2)TiO3−BaTiOGroszewicz1, Breitzke2, Dittmer3 et al. 2014Phys. Rev. B581340View full textAdd to dashboardCite

Nanoscale phase quantification in lead-free(Bi1/2Na1/2)TiO3−BaTiOGroszewicz1, Breitzke2, Dittmer3 et al. 2014Phys. Rev. B581340View full textAdd to dashboardCite

Large pyroelectric properties at reduced depolarization temperature in A-site nonstoichiometry composition of lead-free 0.94Na x Bi y TiO3–0.06Ba z TiO3 ceramics

Electromechanical Anisotropy at the Ferroelectric to Relaxor Transition of (Bi0.5Na0.5)0.94Ba0.06TiO3 Ceramics from the Thermal Evolution of Resonance Curves

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About

Nanoscale phase quantification in lead-free(Bi1/2Na1/2)TiO3−BaTiO
Groszewicz
¹
,
Breitzke
²
,
Dittmer
³

et al. 2014
Phys. Rev. B
58
1
34
0
View full text Add to dashboard Cite

Nanoscale phase quantification in lead-free(Bi1/2Na1/2)TiO3−BaTiO
Groszewicz
¹
,
Breitzke
²
,
Dittmer
³

et al. 2014
Phys. Rev. B
58
1
34
0
View full text Add to dashboard Cite