Thermodynamic properties in the systems vanadium-hydrogen, niobium-hydrogen, and tantalum-hydrogen

Veleckis, E.; Edwards, Russell K.

doi:10.1021/j100723a033

Cited by 327 publications

(131 citation statements)

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“…They also reported that H absorption in the 4 ML thick interface region of the V(110) thin film was substantially suppressed compared with that in the bulk V specimen reported earlier by Veleckis and Edwards [5]. Their experiments were done for the test pieces of V(110) thin films of the thickness between 6.1 ML (1.30 nm) and 3.5 ML (0.74 nm).…”

Section: Introductionmentioning

confidence: 74%

“…Statistical thermodynamic analysis was made some years ago for H absorption in bulk V [6][7][8][9][10] using the P-T-C relationships reported by Veleckis and Edwards [5]. In the present work, statistical thermodynamic analysis is made for H absorption in the epitaxial bcc V (001) thin films to characterise the differences in H absorption performance between the epitaxial bcc V (001) thin film and the bulk V in terms of atomic interaction parameters evaluated by statistical thermodynamics.…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

“…In a preliminary statistical thermodynamic analysis of P-T-C relationships reported for H absorption for Va-group transition metals (V, Nb and Ta) by Veleckis and Edwards [5], it was demonstrated [6] that number θ of available interstitial sites for occupation by H atoms per metal atom was smaller than 1 whereas, in view of mere crystal geometry, θ is as high as 6 provided that T-sites (tetrahedral interstitial sites) are occupied with H atoms or θ = 3 provided that O-sites (octahedral interstitial sites) are occupied with H atoms. The θ value determined was 0.75 for bcc NbH x or 0.55 for bcc VH x and for bcc TaH x [6].…”

Section: Standard Statistical Thermodynamic Analysis Proceduresmentioning

confidence: 99%

“…Equilibrium P-T-C (pressure-temperature-composition) relationships for H absorption in V as well as for the other two Va-group transition metals, Nb and Ta, were measured by Veleckis and Edwards [5] over range of T between 518.6 K and 827 K up to p(H 2 ) = 800 Torr (≈100 Pa) for thin foil test piece using Sieverts' method.…”

Section: Introductionmentioning

confidence: 99%

“…1 in which representative isothermal P-C relationships for bulk V (thin foil in non-constrained condition) [5] and those for epitaxial bcc V (001) thin films [1] are compared. Although direct comparison of the isotherms between the bulk V and …”

Section: Introductionmentioning

confidence: 99%

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Hydrogen absorption in epitaxial bcc V (001) thin films analysed by statistical thermodynamics

Shohoji¹

2010

Thin Solid Films

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Andersson, Aits and Hjörvarsson of Uppsala University measured hydrogen uptake in epitaxial bcc (body centred cubic) vanadium (V) (001) thin films of thickness, 50 nm and 100 nm, over temperature range between 443 K and 513 K. The reported equilibrium pressure-temperature-composition (P-T-C) relationships for the epitaxial bcc V (001) thin films showed appreciable extent of enhancement of H solubility compared with that for bulk bcc V. In this work, the reported equilibrium P-T-C relationships for the epitaxial bcc V(001) thin films by Andersson et al. were analysed in terms of statistical thermodynamics for H 2 gas partial pressure p(H 2 ) up to 100 Pa and H/V mole atom ratio x in VH x up to 1. The present analysis results showed that, up to x = 0.75, the state of H in the V lattice was comparable to that in bulk VH x specimen but that, in the range of x higher than 0.75, state of H in the thin film with the constrained basal plane condition was evidently distinguishable from that in non-constrained bulk VH x . This was concluded to be the consequence of the tetragonal distortion of the bcc lattice with biaxially constrained condition at the bottom surface of the VH x (001) thin film in the range of x exceeding 0.75.

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Section: Introductionmentioning

confidence: 74%

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

Section: Standard Statistical Thermodynamic Analysis Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Hydrogen absorption in epitaxial bcc V (001) thin films analysed by statistical thermodynamics

Shohoji¹

2010

Thin Solid Films

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Dense Carbide/Metal Composite Membranes for Hydrogen Separations Without Platinum Group Metals

et al. 2011

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Equilibrium and kinetics studies of hydrogen isotope exchange on vanadium hydride

Wong

Hill

1979

AIChE Journal

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Chromatography experiments and pressure-composition isotherm measurements were carried out on the vanadium-hydrogen system in order to obtain an understanding of the equilibrium and kinetic factors affecting hydrogen isotope exchange. Analysis of the results yielded values of the hydrogen equilibrium distribution coefficient, the tritium-protium separation factor, the rate of the gas-solid exchange reaction, and the axial dispersion coefficient. SCOPEHydrogen isotope separations of current technical interest include deuterium enrichment for heavy water production and removal of tritium from nuclear industry effluents. Insofar as isotopic composition is concerned, feed streams for these processes consist mainly of the light isotope, protium, with a trace amount of a heavy isotope, deuterium, or tritium. A solid sorbent useful for concentrating the heavy isotope should preferentially take up that isotope.A gas-solid system having this property is the vanadiumhydrogen system. In contrast to most metal hydride systems, the deuteride and tritide are more stable than the protide in the vanadium system. This paper presents a study of the equilibrium and kinetic properties of isotope exchange in the HT-H2-vanadium hydride system. The object of the investigation was to obtain an understanding of the factors affecting isotope exchange which are useful in isotope separation process design and analysis. Equilibrium and rate data were obtained from chromatography experiments conducted on the HT-H2-vanadium hydride system and from measurements of hydrogen-vanadium pressure-composition isotherms. CONCLUSIONS AND SIGNIFICANCEPressure-composition isotherms for the hydrogenvanadium system were determined over the composition range VH-o,6 to VHW1,*. The data in the VH-o.6 region at high temperatures were in good agreement with a correlation of Veleckis and Edwards (1969) which was based on the assumption that hydrogen was in simple interstitial solution in the metal lattice.Chromatography experiments on the HT-H2-V system were conducted in the VII-o,6 region and were interpreted in terms of a model of mass transfer and reaction. Data from these experiments were used in combination with the pressure-composition data to derive the tritium-protium separation factor, the magnitude as well as the temperature and pressure dependence of the gas-solid interfacial exchange rate, and the axial dispersion coefficient. The separation factor decreased approximately linearly with temperature from a value of 1.20 at 4OoC to 1.06 at 300°C.No discontinuity was found at the a-p phase boundary.As expected, the separation factor did not vary with pressure. The interfacial exchange reaction was found to be the rate limiting step in the overall exchange process, being slow compared to mass transfer external to the hydride particles and to diffusion within the particles. The pressure and temperature dependence of the exchange rate was characteristic of mechanisms involving activated chemisorption of hydrogen. Values of the axial dispersion coefficient w...

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Thermodynamic properties in the systems vanadium-hydrogen, niobium-hydrogen, and tantalum-hydrogen

Cited by 327 publications

References 1 publication

Hydrogen absorption in epitaxial bcc V (001) thin films analysed by statistical thermodynamics

Hydrogen absorption in epitaxial bcc V (001) thin films analysed by statistical thermodynamics

Dense Carbide/Metal Composite Membranes for Hydrogen Separations Without Platinum Group Metals

Equilibrium and kinetics studies of hydrogen isotope exchange on vanadium hydride

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