Electrochemical Formation and Chemical Characterization of a Djerfisherite‐Like Compound

Electrochemical apparatus and techniques are described for determining the nature and degree of anodic corrosion of candidate current collector metals for the lithium-iron sulfide molten salt battery. Sufficiently low background currents were achieved to permit measurement of fractional rail-peryear average dissolution rates directly in pure LiCI-KC1 eutectic at ~450~ corresponding to a nearly charged battery, and indirectly in LieS-saturated eutectic, corresponding to the nearly discharged state. Voltammetric studies in Li2S-saturated eutectic with inert electrodes indicate successive sulfide ion oxidation to $2 = and S, and a complex reduction chemistry. Voltammetry on the iron-iron sulfide couple indicates that graphite, platinum, and molybdenum may all be employed as inert indicating electrodes in Li2S-saturated eutectic. The latter melt was observed to attack Pyrex, forming a soluble silicon species capable of reacting with metal surfaces.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.230.243.252 Downloaded on 2014-12-01 to IP Vol. I26, No. 7 LiC1-KC1 EUTECTIC 1093 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.230.243.252 Downloaded on 2014-12-01 to IP

Section: [6]mentioning

confidence: 74%

“…Manuscript submitted Aug. 28, 1978; revised manuscript received Jan. 15, 1979. This was Paper 58 presented at the Atlanta, Georgia, Meeting of the Society, Oct. [9][10][11][12][13][14]1977.…”

Section: Discussionmentioning

confidence: 99%

Anodic Corrosion Rate Measurements in LiCl ‐ KCl Eutectic: I . Electrochemical Considerations

Raleigh

White

Ogden

1979

“…For example, the FeS2 electrode phases include Li3Fe2S4 and a solid-solution phase Li2+xFe1-xS2 that extends from x = 0 to x = 0.33 (21). Even more complex phases are possible; for example, LiKaFe~4S~aC1, which is a common phase in FeS electrodes (22,23), is also found in FeS2 electrodes (21). Thus, the phases in FeS2 electrodes are more complex than is suggested by the Fe-S phase diagram; the phases in CoS2 and NiS2 electrodes have not been previously determined.…”

mentioning

confidence: 99%

Reactions of FeS2, CoS2, and NiS2 Electrodes in Molten LiCl ‐ KCl Electrolytes

Preto

Tomczuk

Winbush

et al. 1983

The electrochemistry of the FeS2 , CoS2 , and NiS2 electrode phases in molten normalLiCl‐normalKCl electrolyte at 400°C was studied using cyclic voltammetry at sweep rates of 0.02–1 mV/sec. Emf's, polarization characteristics, and nucleation overpotentials were obtained for each major electrode reaction; the anodic nucleation overpotentials increased with emf for all three electrodes. The disulfide electrodes lost sulfur during the extended cyclic‐voltammetry tests. These losses appear to be associated with a nonequilibrium species that is involved in the electrochemical formation of the disulfides from their precursors.

“…1. The e x p e r i m e n t a l details and the cell c h e m i s t r y have been reported (1,13). The charge and discharge cutoff voltages were 1.65 and 1.00V, respectively, with the cell being term i n a t e d in an i n t e r m e d i a t e stage of the charging cycle.…”

Section: Methodsmentioning

confidence: 94%

“…It is well known that thermal and/or forced convections in melts cause compositional variation in various semiconductor single crystals (1)(2)(3)(4)(5)(6). Recently, there have been lots of reports published on single crystal growth, using the Czochralski method in a magnetic field to reduce striations due to thermal/forced convection.…”

Section: Fundamental Research Laboratories Nec Corporation Miyamae-mentioning

confidence: 99%

Neutron Diffraction Study of Electrochemically Synthesized Djerfisherite

Tani¹,

Mrazek²,

Faber³

et al. 1986

produces TaSi2 from the diffusion controlled interaction of silicon and Ta.~Si3.The three reactions combine and compete to determine the deposition stoichiometry, structure, and morphology; through these reactions, processing variables can greatly influence the microstructure of the deposited tantalum silicide. The interface roughness between the tantalum silicide and the polysilicon is determined by the competition between the displacement reaction and the silane reaction. In the absence of silane, TaC15 reacts readily with polysilicon to yield a rough interface between the phases. If silane is present in the reactor when the TaCl~ is introduced, the resultant interface between the silicide and polysilicon is much smoother. The grain size and pore density, the whisker density, the deposition rate, and the crystal structure are all strongly influenced by the tantalum chloride to silane ratio. The influence of temperature and total pressure are second-order contributors to the deposition rate and to the film characteristics. AcknowledgmentsWe would like to thank A. C. Adams and H. J. Levinstein for suggesting this work and for their continuing advice and encouragement during the program. Stimulating discussions with S. P. Murarka are also gratefully acknowledged. The special contribution of E. A. Dein to all phases of this program is acknowledged. We acknowledge the electron microscopy of R. V. Knoell, the RBS work of D.C. Jacobson, and the x-ray diffraction work of J. Vandenberg. Finally, we acknowledge the special insight that R. S. Wagner has given to the topic of whisker growth in CVD systems. ABSTRACTThe electrochemical synthesis of a synthetic form of the mineral djerfisherite produced sufficient material (4g) for neutron powder diffraction analysis. The data were collected on the time-of-flight neutron diffractometer at the Intense Pulsed Neutron Source Facility at Argonne National Laboratory. A crystallographic refinement of the neutron diffraction data by the Rietveld analysis technique showed an improvement in the atom coordinate positions by a factor of ten over prior x-ray powder diffraction data. In addition, the refinement indicates 23 iron atoms randomly distributed about 24 available sites such that the formula of the synthetic form of djerfisherite can be expressed as K~LiFez3S2~CI.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14.35