Raman study of SrBi2Ta2O9thin films

Ching-Prado, E.; Pérez, W.; Reynés‐Figueroa, A.; Katiyar, Ram S.; Ravichandran, D.; Bhalla, A. S.

doi:10.1080/07315179908204589

Cited by 4 publications

(4 citation statements)

References 3 publications

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“…The three characteristic peaks in the range of 200-300 cm −1 corresponded to O-Ta-O bending vibration, and the band near 600 cm −1 assigned to a Ta-O-Ta vibration. These two bands are similar to those found in other perovskite systems, such as KNbO 3 [28]. Thus, we could conclude that the SBT nanosheet was successfully fabricated.…”

Section: Catalyst Characterizationsupporting

confidence: 84%

“…In addition, Raman analysis was performed to further assess the structure of SBT. As illustrated in Figure 1b, the peak around 806 cm −1 belongs to the SBT crystallization degree [28]. The three characteristic peaks in the range of 200-300 cm −1 corresponded to O-Ta-O bending vibration, and the band near 600 cm −1 assigned to a Ta-O-Ta vibration.…”

Section: Catalyst Characterizationmentioning

confidence: 93%

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Dark–Light Tandem Catalytic Oxidation of Formaldehyde over SrBi2Ta2O9 Nanosheets

Liu

Lin

et al. 2023

Molecules

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Formaldehyde (HCHO), as one of the main indoor toxic pollutions, presents a great threat to human health. Hence, it is imperative to efficiently remove HCHO and create a good indoor living environment for people. Herein, a layered perovskite material SrBi2Ta2O9 (SBT), was studied for the first time and exhibited superior photocatalytic efficiency and stability compared to commercial TiO2 (P25). Furthermore, a unique dark–light tandem catalytic mechanism was constructed. In the dark reaction stage, HCHO (Lewis base) site was adsorbed on the terminal (Bi2O2)2+ layer (Lewis acid) site of SBT in the form of Lewis acid-base complexation and was gradually oxidized to CO32− intermediate (HCHO → DOM (dioxymethylene) → HCOO− → CO32−). Then, in the light reaction stage, CO32− was completely converted into CO2 and H2O (CO32− → CO2). Our study contributes to a thorough comprehension of the photocatalytic oxidation of HCHO and points out its potential for day–night continuous work applications in a natural environment.

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Section: Catalyst Characterizationsupporting

confidence: 84%

Section: Catalyst Characterizationmentioning

confidence: 93%

Dark–Light Tandem Catalytic Oxidation of Formaldehyde over SrBi2Ta2O9 Nanosheets

Liu

Lin

et al. 2023

Molecules

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“…The SrBi2Ta2O9 and SrBi2Nb2O9 belong to the ABi2B2O9 perovskite-like compounds and have a face-centered orthorhombic unit cell, consisting of TaO6 or NbO6 octahedrons, respectively (see Figure 1). These materials have a relatively high Curie temperature of the ferroelectric phase transition (TC), around 335 o C (for SBT) [19] and around 440 o C (for SBN) [20]. In the ordered perovskite phase at temperatures below TC the spontaneous polarization vector lies in the plane of these layers.…”

Section: Sbtn Atomic Structure and Ferroelectric Propertiesmentioning

confidence: 99%

Effect of Nb cationic substitution on the microstructure and Raman spectra of SrBi2(Ta,Nb)2O9 thin films

Fesenko¹,

Yaremkevich²,

Tsebrienko³

et al. 2022

Preprint

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Micro-Raman spectroscopy and X-ray diffraction have been used to explore the lattice dynamics of Nb-substituted SrBi2(TaxNb1−x)2O9 (SBTN) thin crystalline films annealed at low temperature, 700oC. The relative intensity of the (115), (006) and (200) X-ray diffraction peaks, which correspond to the crystal structure and ferroelectric phase, nonmonotonically increases with the increase of Nb content. It turned out that SBTN films consist of fine-grained spherical structures if the percent of Ta ions substituted by Nb ions is (10–40) wt.%, while the formation of rod-like grains occurs when the percent of Nb ions reaches 50 wt. % due to the stress-induced transformation of the thin film perovskite structure. It was shown that the substitution by Nb of Ta-site in SBT has a pronounced impact on the Raman band around 810 cm− 1, which is assigned to the symmetric stretching modes of the (Ta,Nb)O6 octahedra, leading to the shifting and splitting of this mode. At the same time Nb substitution does not significantly influence on the low frequency Raman modes of SBT. Unexpectedly, we observed the nonmonotonic shift of the Raman band around 810 cm− 1, namely: from 810 cm− 1 (for pure SBT) to ~ 830 cm− 1 (for SBTN with 20–40 wt.% of Nb) and then back to 811 cm− 1 with increasing Nb content up to 50 wt. %. We assume that these changes are conditioned by the ferrodistortion occurring in ferroic perovskites, namely by the tilting distortion of (Ta,Nb)O6 octahedra at (20–50) wt. % of Nb. The octahedral tilting distortion can change the coordination environment of the A-cite cation, as well as it lowers the SBTN symmetry due to the differences in ionic radius and mass between Ta and Nb in the B-sites, that can lead to significant changes of the SBNT crystal structure and symmetry when 50 wt. % of Ta ions is substituted by Nb ions. The same nonmonotonic trends were observed for the ferroelectric perovskite phase fraction and remanent polarization on Nb content in SBTN films. Landau-Devonshire approach is used to explain the experimentally observed nonmonotonic dependence of the ferroelectric perovskite phase fraction and remanent polarization on Nb content in SBTN films, at that the form of the dependence strongly resembles the shift of the Raman band of symmetric stretching modes of the (Ta,Nb)O6 octahedra. Thus, the combination of micro-Raman spectroscopy with X-ray diffraction, ferroelectric measurements and phenomenological description allow to establish the influence of Nb doping on the lattice dynamics, microstructure, phase composition and ferroelectric properties of the SBTN thin films.

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“…The dynamics of the PTs in SBT was investigated first by means of Raman scattering [10][11][12][13] and later by means of Brillouin scattering [14] and Fourier transform infrared (FTIR) reflectivity and transmission spectroscopy [9,15,16]. It was shown that the lowest-frequency optical phonon near 28 cm −1 (at 300 K) reduces its frequency on heating and disappears from the Raman spectra above T c1 due to overdamping and the change of selection rules [10].…”

Section: Introductionmentioning

confidence: 99%

High-temperature phase transitions in SrBi₂Ta₂O₉film: a study by THz spectroscopy

Kadlec¹,

Kamba²,

Kužel³

et al. 2004

J. Phys.: Condens. Matter

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Time-domain THz transmission experiment was performed on SrBi 2 Ta 2 O 9 thick film (deposited on sapphire substrate) at temperatures between 30 and 923 K and complex dielectric spectra of the film were determined. The lowest frequency optic phonon near 28 cm -1 reveals slow monotonous decrease in frequency on heating with no significant anomaly near either the ferroelectric or ferroelastic phase transitions. An additional relaxation mode was resolved in the THz dielectric spectra at all temperatures and its slowing down to ferroelectric phase transition explains dielectric anomaly near T c1 . Second harmonic generation signal was observed in single crystal not only below T c1 but also below T c2 , which confirms the presence of intermediate ferroelastic phase.

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Raman study of SrBi₂Ta₂O₉thin films

Cited by 4 publications

References 3 publications

Dark–Light Tandem Catalytic Oxidation of Formaldehyde over SrBi2Ta2O9 Nanosheets

Dark–Light Tandem Catalytic Oxidation of Formaldehyde over SrBi2Ta2O9 Nanosheets

Effect of Nb cationic substitution on the microstructure and Raman spectra of SrBi2(Ta,Nb)2O9 thin films

High-temperature phase transitions in SrBi₂Ta₂O₉film: a study by THz spectroscopy

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Raman study of SrBi2Ta2O9thin films

Cited by 4 publications

References 3 publications

Dark–Light Tandem Catalytic Oxidation of Formaldehyde over SrBi2Ta2O9 Nanosheets

Dark–Light Tandem Catalytic Oxidation of Formaldehyde over SrBi2Ta2O9 Nanosheets

Effect of Nb cationic substitution on the microstructure and Raman spectra of SrBi2(Ta,Nb)2O9 thin films

High-temperature phase transitions in SrBi2Ta2O9film: a study by THz spectroscopy

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Raman study of SrBi₂Ta₂O₉thin films

High-temperature phase transitions in SrBi₂Ta₂O₉film: a study by THz spectroscopy