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1.
Alain Ibanez Jean-Claude Jumas Josette Olivier-Fourcade Etienne Philippot 《Journal of solid state chemistry》1984,55(1):83-91
The crystal structures of Sn2SbX2I3, with X = S or Se, and Sn3SbSe2I5 are characterized by a statistical disorder of part of the [Sb] and [Sb, Sn] sites. All these crystal structures are built up from infinite ribbons (Sn2X4)n of SnX5 pyramids where X = ((S, Se) and I). The ribbons are weakly linked through Sn … I interactions to give infinite sheets. Between sheets are located [Sb] or [Sb, Sn] atoms in twinned sites. 相似文献
2.
Josette Olivier-Fourcade Costana Mihaela Ionica-Bousquet Pierre-Emmanuel Lippens Jean-Claude Jumas 《Hyperfine Interactions》2012,207(1-3):33-36
Due to their high storage capacity Sn-based materials are of considerable interest as negative electrode for Li-ion batteries. However the strong volume change occurring during the alloy formation strongly limits the electrochemical performances (cycle and time life). Analysis by M?ssbauer spectroscopy using model compounds (Sn, Sn-Li and transition metal-Sn alloys) shows that the volume expansion is related to the structural change from a Sn based network to a Li based network. Two types of materials are proposed here to overcome this problem: tin dispersion in an electrochemically inactive oxide matrix with buffer role to absorb volume changes or tin alloying with an inactive transition metal to minimize the volume expansion. The use of M?ssbauer spectroscopy (in situ operando mode) allows a dynamic approach which is essential to understand the fundamental causes of ageing on cycling and to define then the key issues to be solved for material’s application. 相似文献
3.
Donato Ercole Conte Abdelmaula Aboulaich Josette Olivier-Fourcade Christian Jordy 《Journal of solid state chemistry》2010,183(1):65-6650
A comparative study of two Sn-based composite materials as negative electrode for Li-ion accumulators is presented. The former SnB0.6P0.4O2.9 obtained by in-situ dispersion of SnO in an oxide matrix is shown to be an amorphous tin composite oxide (ATCO). The latter Sn0.72[BPO4]0.28 obtained by ex-situ dispersion of Sn in a borophosphate matrix consists of Sn particles embedded in a crystalline BPO4 matrix. The electrochemical responses of ATCO and Sn0.72[BPO4]0.28 composite in galvanostatic mode show reversible capacities of about 450 and 530 mAh g−1, respectively, with different irreversible capacities (60% and 29%). Analysis of these composite materials by 119Sn Mössbauer spectroscopy in transmission (TMS) and emission (CEMS) modes confirms that ATCO is an amorphous SnII composite oxide and shows that in the case of Sn0.72[BPO4]0.28, the surface of the tin clusters is mainly formed by SnII in an amorphous interface whereas the bulk of the clusters is mainly formed by Sn0. The determination of the recoilless free fractions f (Lamb-Mössbauer factors) leads to the effective fraction of both Sn0 and SnII species in such composites. The influence of chemical composition and especially of the surface-to-bulk tin species ratio on the electrochemical behaviour has been analysed for several Snx[BPO4]1−x composite materials (0.17<x<0.91). The cell using the compound Sn0.72[BPO4]0.28 as active material exhibits interesting electrochemical performances (reversible capacity of 500 mAh g−1 at C/5 rate). 相似文献
4.
The lithium mobility in glasses of composition xLi2S?(1?x)GeS2 has been followed by c.w. (for x = 0.3; 0.4 and 0.5) and pulsed NMR (for x = 0.3 and 0.5) between ? 150 and + 280°C.The second moment of the resonance line of 7Li(0.89–1.51 G2) is proportional to the molar fraction of Li2S, which may be correlated to an homogeneous Li nuclei distribution.The resonance line profiles and their thermal evolution seem to show that some Li+ ions do not participate in the conduction.Thermal variation of the spin-lattice relaxation time T1, shows a strongly asymmetrical shape, if one considers In on both sides of the observed maxima. This behaviour may be explained by a distribution of the Li correlation times τ corresponding to different jump distances between various possible sites. The Cole-Davidson model allows the best agreement between experimental and theoretical values of the correlation times.The activation energies deduced from this model are close to those obtained from conductivity measurements (0.43 eV by NMR, 0.56 eV by conductivity determinations for x = 0.50), they may be correlated to the longer Li+ jumps in the vitreous matrix. 相似文献
5.
6.
Jean-Claude Jumas Moulay Tahar Sougrati Alexis Perea Laurent Aldon Josette Olivier-Fourcade 《Hyperfine Interactions》2013,217(1-3):107-115
The performances of Li-ion batteries depend on many factors amongst which the important ones are the electrode materials and their structural and electronic evolution upon cycling. For a better understanding of lithium reactivity mechanism of many materials the combination of X-Ray Powder Diffraction (XRPD) and Transmission Mössbauer Spectroscopy (TMS) providing both structural and electronic information during the electrochemical cycling has been carried out. Thanks to the design of a specific electrochemical cell, derived from a conventional Swagelock cell, such measurements have been realised in operando mode. Two examples illustrate the greatness of combining XRPD and TMS for the study of LiFe0.75Mn0.25PO4 as positive electrode and TiSnSb as negative electrode. Different kinds of insertion or conversion reactions have been identified leading to a better optimization and design of performing electrodes. 相似文献
7.
Aldon L. Kubiak P. Picard A. Lippens P. E. Olivier-Fourcade J. Jumas J.-C. 《Hyperfine Interactions》2004,156(1-4):497-503
Hyperfine Interactions - The use of 57Fe as a local Mössbauer probe is of high interest for studying mechanisms induced by lithium insertion. In this way the substitutions Ti/Fe and Li/Fe have... 相似文献
8.
J.-P. Candy E. Roisin J.-M. Basset D. Uzio S. Morin L. Fischer J. Olivier-Fourcade J.-C. Jumas 《Hyperfine Interactions》2005,165(1-4):55-60
The diamond-bearing gravels found along South Africa's West Coast are being beneficiated by means of dense medium separation (DMS) to reclaim the alluvial diamonds. Granular ferrosilicon (Fe–Si) is used as the DMS material and at the end of each operation the Fe–Si is reclaimed from the process stream using a magnetic separator and is then recycled but losses of Fe–Si due to attrition, adhesion to the separation products, density changes and changes to the magnetic properties can occur. The gravel obtained from the mining operation is washed and screened before heavy mineral separation. The concentrate, tailings and Fe–Si samples were investigated by means of SEM and Mössbauer spectroscopy to determine where changes to the Fe–Si, or contamination could occur. The composition of the Fe–Si was determined to be Fe (76.1 at.%), Si (20.3 at.%), Mn (1.5 at.%), Al (1.5 at.%) and Cr (0.6 at.%) resulting in a more or less ordered DO3 phase with a calculated composition of Fe3Si for this Fe–Si, consistent with the Mössbauer results where two sextets with hyperfine magnetic fields of 18.6 T and 28.4 T were observed. After DMS, magnetite and ilmenite, the minerals found in the gravel, were still present in the concentrate. In the tailings virtually no magnetite or ilmenite was found and only a doublet, identified as an oxihydroxide, due to the abrasion of the Fe–Si, was found. After magnetic separation, to wash and clean the Fe–Si for re-use, it was found that magnetite and ilmenite were still present in the Fe–Si, which results in a change in density of the Fe–Si, resulting in a higher density and loss of valuable diamonds. 相似文献
9.
Josette Olivier-Fourcade Manfred Womes Jean-Claude Jumas Fabienne Le Peltier Stéphane Morin Blaise Didillon 《Chemphyschem》2004,5(11):1734-1744
Alumina-supported Sn and PtSn particles are studied by 119Sn M?ssbauer spectroscopy after oxidation and reduction under various conditions. The observed species of Sn(IV), Sn(II) and Sn(0) are grouped in several categories, each being characterised by distinct structural properties. Tin phases in contact with the support or with platinum are identified. The results are used to establish a model describing the phase transformations occurring in PtSn particles under oxidising or reducing conditions. Particular attention is paid to the reduction/reoxidation mechanisms governing H2/O2 double titrations. An increased reactivity of tin towards oxygen, induced by the contact with platinum, is demonstrated. It is shown that tin contributes to the oxygen uptake VO1 of a first titration cycle by platinum-catalysed transformation of Sn(II) into an oxometallic phase Pt(x)Sn(O). The oxygen titre VO2 of a second cycle is due to O2 chemisorption on platinum only. 相似文献
10.
Dedryvère R. Uhrmacher M. Lohstroh A. Picard-Garcia A. Olivier-Fourcade J. Jumas J.-C. 《Hyperfine Interactions》2001,136(3-8):479-484
The electrochemical insertion of lithium into β-In2S3 at different concentrations has been investigated by means of γγ-Perturbed Angular Correlations measurements using implanted
radioactive 111In nuclei. The study of the hyperfine interactions of the 111Cd nuclei during the decay 111In(EC)111Cd allowed to determine the evolution of the three observed electric field gradients at different temperatures and lithium
contents. This study reveals a great difference of behavior between the three indium sites of the structure, and shows the
mobility of indium ions and their partial reduction after lithium insertion. In2S3 is good model material to study the properties of more complex materials based on this structure, which may be used as electrodes
for lithium-ion batteries.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献