Molecular relaxation processes in the salt systems containing anions of various configurations

Гафуров, М. М.; Aliev, A. R.

doi:10.1016/j.saa.2003.06.004

Cited by 18 publications

(6 citation statements)

References 25 publications

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“…[32] If the larger atomic or covalent radii or longer bond length of K (as K-O) is responsible for the higher vibrational mode in KReO 4 , then there should be fewer K + coordinated per ReO 4 À . Fewer coordinating K + per ReO 4 À , relative to the number of coordinating Na + per ReO 4 À , is consistent with observations by Gafurov and Aliev [33] that 'the number of the complexing ions becomes smaller with enlargement of the ionic radius of the cation' in alkali metal salts. Alternatively, one could pose that the degree of covalency experienced by each ReO 4 À is higher in NaReO 4 (and possibly NaTcO 4 ) because there are more Na-O nearest neighbors sharing charge with the ligand.…”

Section: Crystalline Phasessupporting

confidence: 90%

Raman analysis of perrhenate and pertechnetate in alkali salts and borosilicate glasses

Gassman

McCloy

Soderquist

et al. 2014

J Raman Spectroscopy

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Sodium borosilicate glasses containing rhenium or technetium were fabricated and their vibrational spectra studied using confocal Raman microscopy. Glass spectra were interpreted relative to new high-resolution spectra of pure crystalline NaReO 4 , KReO 4 , NaTcO 4 , and KTcO 4 salts. Spectra of perrhenate and pertechnetate glasses exhibited sharp Raman bands, characteristic of crystalline salt species, superimposed on spectral features of the borosilicate matrix. At low concentrations of added KReO 4 or KTcO 4, the characteristic pertechnetate and perrhenate features are weak, whereas at high additions, sharp peaks from crystal field-splitting and C 4h symmetry dominate glass spectra, clearly indicating ReO 4 À or TcO 4 À is locally coordinated with K and/or Na. Peaks indicative of both K and Na salts are evident in many Raman spectra, with the Na form being favored at high concentrations of the source chemicals, where more K + is available for ion exchange with Na + from the base glass. The observed ion exchange likely occurred within depolymerized channels where nonbridging oxygens create segregation from the glass network in regions containing anions such as ReO 4 À and TcO 4 À as well as excess alkali cations. Although this anion exchange provides evidence of chemical mixing in the glass, it does not prove the added salts were homogeneously incorporated in the glass. The susceptibility to ion exchange from the base glass indicates that long-term immobilization of Tc in borosilicate glass must account for excess charge compensating alkali cations in melt glass formulations. Published 2014. This article is a U. S. Government work and is in the public domain in the USA.Additional supporting information may be found in the online version of this article at the publisher's web site.

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Section: Crystalline Phasessupporting

confidence: 90%

Raman analysis of perrhenate and pertechnetate in alkali salts and borosilicate glasses

Gassman

McCloy

Soderquist

et al. 2014

J Raman Spectroscopy

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“…This work considers ionic liquids based on the 1-ethyl-3-methylimidazolium cation, [C 2 C 1 im] + , and a sequence of cyanate-anions of increasing symmetry: thiocyanate, [ 4 ] − . The [SCN] − anion has been already the subject of several Raman band shape studies of alkali cation salts in aqueous solution and high temperature molten state [15][16][17][18][19]. The CN band shape in [C 2 C 1 im][SCN] is expected to differ from molten alkali thiocyanates because of differences in cation size and temperature, so that the analysis allows for interesting comparisons between the ionic liquid and high temperature molten salts.…”

Section: Introductionmentioning

confidence: 99%

Raman band shape analysis of cyanate-anion ionic liquids

Penna

Faria

Ribeiro

2015

Journal of Molecular Liquids

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“…Many spectroscopic studies have focused on ammonium perrhenate (NH 4 ReO 4 ), − which is the most common commercial form of Re. Korppi-Tommola et al., for example, examined the temperature dependence of the Raman spectrum of NH 4 ReO 4 .…”

Section: Introductionmentioning

confidence: 99%

Theoretical Prediction of Rhenium Separation from Ammonium Perrhenate by Phonon–Photon Resonance Absorption

Cao

Qin

et al. 2022

ACS Omega

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Rhenium (Re) is an extremely rare and precious element that is mainly used in the construction of aerospace components and satellite stations. However, an efficient and simple method for preparing Re has yet to be devised. To this end, we investigated the vibrational spectrum of ammonium perrhenate (NH 4 ReO 4 ) using the CASTEP code based on first-principles density functional theory. We assigned the infrared (IR) absorption and Raman scattering spectra for NH 4 ReO 4 using a dynamic process analysis of optical branch normal modes. We examined the IR-active peaks of Re-related vibrational modes in detail and found that the typical IR peak at approximately 914 cm −1 is due to the Re−O bond stretching. Thus, we posit that strong terahertz laser irradiation of NH 4 ReO 4 at 914 cm −1 will lead to sufficient resonance absorption to cleave its Re−O bonds. This method could potentially be used to efficiently separate Re from its oxides.

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Molecular relaxation processes in the salt systems containing anions of various configurations

Cited by 18 publications

References 25 publications

Raman analysis of perrhenate and pertechnetate in alkali salts and borosilicate glasses

Raman analysis of perrhenate and pertechnetate in alkali salts and borosilicate glasses

Raman band shape analysis of cyanate-anion ionic liquids

Theoretical Prediction of Rhenium Separation from Ammonium Perrhenate by Phonon–Photon Resonance Absorption

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