Etudes infrarouges [20–3500 cm−1] et Raman de monocristaux isotopiques de LiCH3COO, 2H2O. Effets de temperature

Cadéne, M.; Vergnoux, A.M.

doi:10.1016/0584-8539(72)80137-5

Cited by 19 publications

(11 citation statements)

References 16 publications

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“…The isotopic exchange of hydrogen atoms by deuterium atoms leads to a significant change of the thermal expansion coefficients and the temperature of the transition from the dynamically disordered high temperature phase to the ordered low temperature phase increases by %5.5 K. The present study complements these earlier findings in that here we study the temperature dependence of the heat capacity of methyl-monodeuterated lithium acetate dihydrate, LiAc-CH 2 D. In addition, we present Raman spectra of LiAc-CH 2 D at ambient pressure to explore the effect of isotopic exchange on the lattice dynamics. This complements works of Ananthanarayanan [6], Cadene et al [7], and Cadene [8] who presented Raman spectra of fully protonated crystals and of Cadene and Vergnoux [9] and Vazquez and Hase [10] who investigated on samples with different isotopic substitution other than partial methyl-deuteration.…”

Section: Introductionsupporting

confidence: 85%

Evidence for low-temperature isotopic ordering in methyl-monodeuterated lithium acetate dihydrate

Schröder

Winkler

Bauer

et al. 2012

The Journal of Chemical Thermodynamics

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Section: Introductionsupporting

confidence: 85%

Evidence for low-temperature isotopic ordering in methyl-monodeuterated lithium acetate dihydrate

Schröder

Winkler

Bauer

et al. 2012

The Journal of Chemical Thermodynamics

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“…This phase transition has been shown to be induced upon deuteration of the methyl groups [1][2][3][4][5]. Its critical temperature increases with the increase of the deuteration rate of these groups.…”

Section: Introductionmentioning

confidence: 99%

“…Also, this phase transition presents certain experimental aspects that seem to connect the onset of the phase transition to a mechanism involving the lattice dynamics [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

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An Experimental Study of the Lattice Dynamics in Fully Deuterated Lithium Acetate Dihydrate

et al. 2008

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Fully deuterated lithium acetate dihydrate undergoes a structural phase transition at low temperatures. We have undertaken a systematic study of the low-frequency lattice mode dispersion curves, along a previously determined path in the Brillouin zone, in the high and the low temperature phases, as well as in the vicinity of T c . A set of low frequency optical modes was detected and their symmetries attributed. In accordance with previous results, we propose assigning some of them to complex vibrations involving acetate and the water molecule librations.We propose thus a coupling mechanism between the two possible reorientations of the methyl groups and one of the low frequency lattice vibrations in the vicinity of T c .

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“…Considering the crystal structure data on the first coordination sphere of the metal ions in 1:1 and 1:2 citrate complexes [14][15][16][17], this splitting can be explained in terms of monodentate and bridging carboxylate coordination. For comparison, Table 1 gives two characteristic examples for monodentate and bridging CO2-coordination: Ni(Ac)2.4H20 (where a network of hydrogen bond is developed) and LiAc.2H20, respectively [19,20].…”

Section: Lithium-cobalt Citrate Precursorsmentioning

confidence: 99%

Ultrafine layered LiCoO2 obtained from citrate precursors

Zhecheva

Stoyanova

Gorova

et al. 1997

Ionics

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Abstract.A new method for the preparation of ultrafine LiCoO2 with a layered crystal structure was developed, which consists in thermal pyrolysis of homogeneous lithium-cobalt-citrate precursors. Atomic scale mixing of Li and Co is achieved by citric acid acting as a chelating agent. Electron spectroscopy of concentrated Li-Co-citrate solutions with Li:Co:Cit=l: 1:1 and Li:Co:Cit=l:l:2 reveals that the predominant species at pH=7 are [C0(C6H507) ]-and [Co(C6H507)2] 4" complexes. Freeze-drying of the two types of solutions leads to the formation of LiCo(C6HsO7).nH20 and (NH4)3LiCo(C6HsO7)2.nH20 precursors, where Co 2+ ions are complexed by one and two triionized citrate ions, respectively, and Li § ions serve as counter ions. Between 400-600 ~ the thermal decomposition of these metal-citrate precursors yields LiCoO2 with layered and pseudo-spinel structure, the proportion between them being depending on: (i) the Co/citrate ratio; (ii) the concentration of the freeze-dried solution; (iii) the heating rate. At 400 ~ the most defectless layered LiCoO2, consisting of hexagonal individual particles with dimensions of 120-170 nm, is a product of the bis-citrate decomposition with a slow heating rate. For this sample, heating up to 600 ~ does not affect the crystal size dimensions. For ultrafine layered LiCoO 2 and LiCoO 2 obtained by solid state reaction at high-temperatures (850 ~ the deintercalation and intercalation reactions proceed in the 3.95 -3.99 and 3.86 -3.88 voltage intervals, respectively. For defect trigonal LiCoO2, additional oxidation and reduction peaks at 3.7 -3.8 and 3.4 -3.5 V were observed. We did not succeed in preparing monophase LiCoO2 with pseudo-spinel structure.

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Etudes infrarouges [20–3500 cm−1] et Raman de monocristaux isotopiques de LiCH3COO, 2H2O. Effets de temperature

Cited by 19 publications

References 16 publications

Evidence for low-temperature isotopic ordering in methyl-monodeuterated lithium acetate dihydrate

Evidence for low-temperature isotopic ordering in methyl-monodeuterated lithium acetate dihydrate

An Experimental Study of the Lattice Dynamics in Fully Deuterated Lithium Acetate Dihydrate

Ultrafine layered LiCoO2 obtained from citrate precursors

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