Disorder in Strontium Barium Niobate: Local Structure, Phonons, and Polarization Dynamics

Buixaderas, E.; Paściak, Marek

doi:10.1109/tuffc.2020.2984829

Cited by 4 publications

(6 citation statements)

References 47 publications

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“…Accordingly, the contribution to the macroscopic polarization from Nb(1) and Nb(2) atoms will be different. Displacements of Me (Ba, Sr and Nb) atoms from middle oxygen layers in the direction normal to the tetragonal axis z result in ferroelectric polarization [2,8]. Of interest in the Raman spectra is the line at 636 cm −1 , the phonons of this line are polarized along the z axis, in the direction of which, according to [14], atoms in SBN (the NbO 6 octahedron) are displaced during the FE PT.…”

Section: Resultsmentioning

confidence: 99%

“…The lattice dynamics at FE phase transition (PT) in SBN is affected by many factors, one of which, according to the Raman spectroscopy data [8], is the ratio of Ba/Sr. The analysis of temperature behavior of individual lines (near 630 cm −1 ) in the Raman spectra reported in [9] has shown an almost linear decrease in the Curie temperature (Tc) with an increase in Sr content, that was correlated with the dielectric spectroscopy data [10].…”

Section: Introductionmentioning

confidence: 99%

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Phase transformations in barium-strontium niobate SBN-50 in the temperature range from 80 K to 700 K according to Raman spectroscopy data

Yu.

Анохин

Pavlenko

2022

Physics of the Solid State

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The lattice dynamics of the Sr0.5Ba0.5Nb2O6 (SBN-50) ceramic was studied using Raman spectroscopy in the temperature range of 80-700 K with a step of 10 K. The analysis of the Raman spectra in the range ν=50-1000 cm-1 revealed features in the temperature dependence behavior of the optical modes frequencies associated with the displacement of Ba, Sr and Nb atoms from their average positions in the crystal lattice, which is associated with a macroscopic phase transition from the paraelectric to the ferroelectric phase in the vicinity of 390 K. It is shown that anomalies at T~565 K on the temperature dependences of the frequency and line half-width corresponding to the oscillations of the NbO6 octahedron can be caused by the presence of polar nanoregions in the paraelectric phase in SBN-50. When the sample was cooled to a temperature of 80 K, the behavior was recorded in the Raman spectra, indicating the occurrence of a structural phase transition in the ferroelectric phase in the vicinity of 190 K. The reasons for the revealed patterns are discussed. Keywords: ferroelectric, Raman scattering, SBN, tetragonal tungsten bronze.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phase transformations in barium-strontium niobate SBN-50 in the temperature range from 80 K to 700 K according to Raman spectroscopy data

Yu.

Анохин

Pavlenko

2022

Physics of the Solid State

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“…Соответственно, вклад в макроскопическую поляризацию от атомов Nb(1) и Nb(2) будет различен. Смещения атомов Me (Ba, Sr и Nb) из средних кислородных слоев в направлении, нормальном к тетрагональной оси z , приводят к сегнетоэлектрической поляризации [2,8]. Интерес представляет линия на 636 cm −1 , фононы этой линии поляризованы вдоль оси z , в направлении которой, согласно [14], атомы в SBN (октаэдра NbO 6 ) смещаются в процессе СЭ фазового перехода.…”

Section: экспериментальные результаты и обсужденияunclassified

“…На динамику решетки при СЭ фазовом переходе (ФП) в SBN влияют многие факторы, одним из которых по данным спектроскопии КРС [8] является отношение Ba/Sr. В работе [9] анализ температурного поведения отдельных линий (около 630 cm −1 ) в спектрах КР показал практически линейное уменьшение температуры Кюри (Tc) с увеличением содержания Sr, что коррелировало с данными диэлектрической спектроскопии [10].…”

Section: Introductionunclassified

Фазовые Превращения В Ниобате Бария-Стронция SBN-50 В Интервале Температур От 80 до 700 K По Данным Спектроскопии КРС

Матяш¹,

Анохин²,

Павленко³

2022

Физика Твердого Тела

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The dynamics lattice of the Sr0.5Ba0.5Nb2O6 (SBN-50) ceramic was studied using Raman spectroscopy in the temperature range of 80-700 K with a step of 10 K. The analysis of the Raman spectra in the range ν = 50-1000 cm-1 revealed features in the temperature dependence behavior of the optical modes frequencies associated with the displacement of Ba, Sr and Nb atoms from their average positions in the crystal lattice, which is associated with a macroscopic phase transition from the paraelectric to the ferroelectric phase in the vicinity of 390 K. It is shown that anomalies at T~ 565 K on the temperature dependences of the frequency and line half-width corresponding to the oscillations of the NbO6 octahedron can be caused by the presence of polar nanoregions in the paraelectric phase in SBN-50. When the sample was cooled to a temperature of 80 K, the behavior was recorded in the Raman spectra, indicating the occurrence of a structural phase transition in the ferroelectric phase in the vicinity of 190 K. The reasons for the revealed patterns are discussed.

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“…A fundamental understanding of the origins of dielectric relaxation and ways to control the relaxor-to-ferroelectric crossover in tetragonal tungsten bronzes (TTBs) continues to attract the interest of the materials science and physics communities. Despite decades of research, the exact nature of structural distortions in these systems and the mechanisms of their dielectric and polar responses remain uncertain. − The TTB structure, A1A2 2 B1B2 4 O 15 , differs from the more widely studied and exploited perovskites by the connectivity of oxygen octahedra, as depicted in Figure , which results in a tetragonal archetypical unit cell . The tiling of octahedra in the { ab } layers creates 12-fold (A1) and 15-fold (A2) oxygen coordination environments available to the A cations (the triangular channels typically remain empty).…”

Section: Introductionmentioning

confidence: 99%

Incommensurate Modulation and Competing Ferroelectric/Antiferroelectric Modes in Tetragonal Tungsten Bronzes

et al. 2022

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The nanoscale structure of Sr0.61Ba0.39Nb2O6, a classic uniaxial relaxor ferroelectric crystallizing with the tetragonal tungsten bronze (TTB) structure and exhibiting an incommensurate modulation, has been determined by atomistic refinements using combined data from variable-temperature neutron total scattering, extended X-ray absorption fine structure, and three-dimensional single-crystal diffuse scattering. We found the modulation to arise from the intergrowth of structural slabs featuring distinct types of octahedral rotations directed to minimize octahedral deformations. This modulation involves displacements of the A cations (Sr and Ba) but exerts no significant effect on the polar displacements of Nb. Our results demonstrated the coexistence of competing polar Γ3 – and antipolar Γ2 – modes for off-centering of Nb above the nominal ferroelectric transition temperature of 350 K. The nanoscale-correlated antipolar distortions, which exhibit their largest amplitudes at 425 K, are suppressed below the transition. We identified coupling between the polar off-centering of Nb on its two symmetrically distinct sites as a fundamental characteristic controlling the ferroelectric-to-relaxor crossover in TTBs. We then used it to propose a simple microscopic interpretation for the previously established empirical trend that links crystal–chemical parameters in these systems to their polar response.

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Disorder in Strontium Barium Niobate: Local Structure, Phonons, and Polarization Dynamics

Cited by 4 publications

References 47 publications

Phase transformations in barium-strontium niobate SBN-50 in the temperature range from 80 K to 700 K according to Raman spectroscopy data

Phase transformations in barium-strontium niobate SBN-50 in the temperature range from 80 K to 700 K according to Raman spectroscopy data

Фазовые Превращения В Ниобате Бария-Стронция SBN-50 В Интервале Температур От 80 до 700 K По Данным Спектроскопии КРС

Incommensurate Modulation and Competing Ferroelectric/Antiferroelectric Modes in Tetragonal Tungsten Bronzes

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