Raman scattering investigation of order-disorder phase transitions in cadmium tris(thiourea) sulphate (CTS)

Oussaïd, M.; Becker, P.; Carabatos‐Nédelec, C.

doi:10.1002/1097-4555(200006)31:6<529::aid-jrs572>3.0.co;2-9

Cited by 13 publications

(7 citation statements)

References 16 publications

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“…It is worthy to note that the thermal coefficient related to the changes of the Raman shift positions increases, which can be explained by an important weakening of the van der Waals interaction, and the alkyl chains of the cation gain motional freedom . The cation geometry can be changed from symmetric crosses to broken crosses below the phase transition.…”

Section: Resultsmentioning

confidence: 99%

Raman scattering and alternative current conduction mechanism of the high‐temperature phase transition in [(C₄H₉)₄N]₃Bi₂Cl₉

Trigui

Oueslati

Hlel

et al. 2016

J Raman Spectroscopy

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The tri‐tetrabutylammonium nonachlorobibismuthate(III) was found to crystallize in the monoclinic P21/n space group. Two reversible order–disorder phase transitions are observed at 434/430 K and 477/473 K by differential scanning calorimetry technique. The evolution of Raman wavenumber versus temperature shows a remarkable shifting of the bands associated to alkyl chains, suggesting that the phase transition is governed by the reorientational motion of the organic part [(C4H9)4N]+. The analysis of Nyquist plots has revealed the contribution of two electrical active regions corresponding to the bulk mechanism and the distribution of grain boundaries. The AC conductivity is analyzed by different processes: the non‐overlapping small polaron tunneling model proposed as a closely good model for region I and the correlated barrier hopping attributed to the conduction mechanism for region II. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

Raman scattering and alternative current conduction mechanism of the high‐temperature phase transition in [(C₄H₉)₄N]₃Bi₂Cl₉

Trigui

Oueslati

Hlel

et al. 2016

J Raman Spectroscopy

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“…For the structures of other cadmium-sulfate-thiourea compounds, see: Cavaica et al (1970); Corao & Baggio (1969); Oussaid et al (2000). For the NMR measurement, see: Jalilehvand et al (2012).…”

Section: Related Literaturementioning

confidence: 99%

“…A survey in the crystal structure database shows that mixing cadmium sulfate (CdSO 4 ) with thiourea (TU) in the mole ratio 1:3 results in either monomeric [Cd(TU) 3 (SO 4 )] (Oussaid et al, 2000;Cavaica et al, 1970), (or dimeric [Cd(µ-TU) (TU) 2 (SO 4 )] 2 complexes (Corao & Baggio, 1969) with the cadmium ion coordinating four (CdS 3 O) or five (CdS 4 O) ligand atoms, respectively.…”

Section: S1 Commentmentioning

confidence: 99%

Tetraaquabis(thiourea-κS)cadmium(II) triaquatris(thiourea-κS)cadmium(II) disulfate

Parvez¹,

Jalilehvand²,

Amini³

2012

Acta Cryst E

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The title compound, [Cd(CH4N2S)2(H2O)4][Cd(CH4N2S)3(H2O)3](SO4)2, contains two molecules of each of the Cd complexes and four sulfate ions in the asymmetric unit: all the Cd atoms exhibit distorted octahedral geometries. The Cd—S and Cd—O bond lengths around the Cd atoms in the bis(thiourea) cations are in the ranges 2.580 (4)–2.599 (4) and 2.323 (8)–2.421 (9) Å, respectively, and the S atoms are in a cis orientation. In the tris(thiourea) cations, the corresponding bond lengths around the Cd atoms are slightly longer and are in the ranges 2.559 (4)–2.706 (3) and 2.303 (7)–2.480 (10) Å, respectively, and the S atoms are in a fac disposition. The crystal structure features numerous N—H⋯O, N—H⋯N, O—H⋯O and O—H⋯N hydrogen bonds. Two O atoms of a sulfate anion were found to be disordered over two orientations in a 0.620 (9):0.380 (9) ratio. The crystal studied was a racemic twin with BASF = 0.17 (5)

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“…The FWHM of Raman mode at 961.9 cm −1 related to stretching vibration of ν(ReO) mode and stretching vibration of ν(C─N) mode at 803 cm −1 is plotted as a function of temperature in Figure . It is believed that during order–disorder phase transition, activation energy plays a crucial role as a function of temperature . In Figure a, the experimental values of the FWHM of mode at 961.9 cm −1 is fitted by using Equation .…”

Section: Resultsmentioning

confidence: 99%

Raman evolution of order–disorder phase transition in multiaxial molecular ferroelectric thin film

Zafar

Guo

et al. 2019

J Raman Spectroscopy

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Multiaxial molecular ferroelectrics (MFe) attain great attention due to their number of equivalent ferroelectric axes, an essential characteristic for many applications of these polar polycrystalline materials. Here we report a systematic approach to reveal the temperature‐dependent Raman spectroscopic investigation of the vibrational properties of a [Hdabco]ReO4 (dabco = 1,4‐diazabicyclo[2.2.2]octane), a multiaxial MFe thin film. The Raman spectra allowed to obtain information relative to the change in molecular symmetry governed by the order–disorder phase transition. This phase transition is manifested by the temperature‐dependent peak shift, full width half maximum and intensity of distinct vibrational modes. The experimental observation reveals that ferroelectric phase transition is mainly driven by the reorientation motion of the ReO4− anions and monopronated dabco cations. Hence, we demonstrated that the Raman spectroscopy is a very useful tool to characterize the newly emerged MFe system.

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Raman scattering investigation of order-disorder phase transitions in cadmium tris(thiourea) sulphate (CTS)

Cited by 13 publications

References 16 publications

Raman scattering and alternative current conduction mechanism of the high‐temperature phase transition in [(C₄H₉)₄N]₃Bi₂Cl₉

Raman scattering and alternative current conduction mechanism of the high‐temperature phase transition in [(C₄H₉)₄N]₃Bi₂Cl₉

Tetraaquabis(thiourea-κS)cadmium(II) triaquatris(thiourea-κS)cadmium(II) disulfate

Raman evolution of order–disorder phase transition in multiaxial molecular ferroelectric thin film

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Raman scattering investigation of order-disorder phase transitions in cadmium tris(thiourea) sulphate (CTS)

Cited by 13 publications

References 16 publications

Raman scattering and alternative current conduction mechanism of the high‐temperature phase transition in [(C4H9)4N]3Bi2Cl9

Raman scattering and alternative current conduction mechanism of the high‐temperature phase transition in [(C4H9)4N]3Bi2Cl9

Tetraaquabis(thiourea-κS)cadmium(II) triaquatris(thiourea-κS)cadmium(II) disulfate

Raman evolution of order–disorder phase transition in multiaxial molecular ferroelectric thin film

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Raman scattering and alternative current conduction mechanism of the high‐temperature phase transition in [(C₄H₉)₄N]₃Bi₂Cl₉

Raman scattering and alternative current conduction mechanism of the high‐temperature phase transition in [(C₄H₉)₄N]₃Bi₂Cl₉