Thermodynamics and kinetics of the thin film magnesium–hydrogen system

Vermeulen, P Paul; Ledovskikh, A Alexander; Danilov, Dmitri L.; Notten, Phl Peter

doi:10.1016/j.actamat.2009.06.058

Cited by 24 publications

(27 citation statements)

References 30 publications

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“…Thus, based on room temperature electrochemical measurements of hydrogen equilibrium pressures, Vermeulen et al [24] calculated the enthalpy of hydride formation (−72 kJ/molH 2 ) and decomposition (−74 kJ/molH 2 ) in 200 nm MgH 2 films, which is found quite similar to bulk values mentioned above. Their estimates, however, are based on one temperature only (298 K) and assume the entropy of hydride formation of −130.8 J/K molH 2 in absorption and desorption.…”

Section: Hydrogenography Experiments On Mg/ta/pd Filmssupporting

confidence: 52%

“…The enthalpy of hydride decomposition, −71.0 ± 4.2 kJ/molH 2 , is relatively close to the electrochemistry data, but in a disagreement with the hydrogenography. [3] and MgH 2 -V 3at.%-Ti 2at.% [26], thin [24] and thick MgH 2 films [25] are shown for comparison. Red diamonds are the calculated absorption and desorption equilibrium pressures from the Van't Hoff equation using Pedersen [22] and Stampfer [11] thermodynamic parameters, respectively.…”

Section: Hydrogenography Experiments On Mg/ta/pd Filmsmentioning

confidence: 99%

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Thermodynamic Properties, Hysteresis Behavior and Stress-Strain Analysis of MgH2 Thin Films, Studied over a Wide Temperature Range

2012

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Using hydrogenography, we investigate the thermodynamic parameters and hysteresis behavior in Mg thin films capped by Ta/Pd, in a temperature range from 333 K to 545 K. The enthalpy and entropy of hydride decomposition, ∆H des = −78.3 kJ/molH 2 , ∆S des = −136.1 J/K molH 2 , estimated from the Van't Hoff analysis, are in good agreement with bulk results, while the absorption thermodynamics, ∆H abs = −61.6 kJ/molH 2 , ∆S abs = −110.9 J/K molH 2 , appear to be substantially affected by the clamping of the film to the substrate. The clamping is negligible at high temperatures, T > 523 K, while at lower temperatures, T < 393 K, it is considerable. The hysteresis at room temperature in Mg/Ta/Pd films increases by a factor of 16 as compared to MgH 2 bulk. The hysteresis increases even further in Mg/Pd films, most likely due to the formation of a Mg-Pd alloy at the Mg/Pd interface. The stress-strain analysis of the Mg/Ta/Pd films at 300-333 K proves that the increase of the hysteresis occurs due to additional mechanical work during the (de-)hydrogenation cycle. With a proper temperature correction, our stress-strain analysis quantitatively and qualitatively explains the hysteresis behavior in thin films, as compared to bulk, over the whole temperature range. OPEN ACCESSCrystals 2012, 2 711

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Section: Hydrogenography Experiments On Mg/ta/pd Filmssupporting

confidence: 52%

Section: Hydrogenography Experiments On Mg/ta/pd Filmsmentioning

confidence: 99%

Thermodynamic Properties, Hysteresis Behavior and Stress-Strain Analysis of MgH2 Thin Films, Studied over a Wide Temperature Range

2012

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“…Formation of a continuous layer of MgH 2 has often been observed to effectively block further hydrogenation when the particles are too large. [2][3][4] Although the stability is a very important issue, the vast majority of efforts are directed at improving the kinetics. One possibility is to try and eliminate the diffusion limitations by reducing the grain size and/or particle size, typically to 10 nm or less.…”

mentioning

confidence: 99%

Effect of alloying magnesium with chromium and vanadium on hydrogenation kinetics studied with neutron reflectometry

Kalisvaart

Luber

Fritzsche³

et al. 2011

Chem. Commun.

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“…[6][7][8] Many microscopic parameters, such as interaction energies between absorbed hydrogen atoms, can be obtained by fitting the experimental data. The LGM agrees well with the experimental results of various hydride-forming materials.…”

mentioning

confidence: 99%

“…9 KM is based on the principles of statistical thermodynamics, described in LGM, [6][7][8] and also takes into account the complex gas-phase ͑de͒hydrogenation kinetics. The advantage of this kinetic approach is that it can, in principle, describe both equilibrium and nonequilibrium ͑dynamic͒ conditions.…”

mentioning

confidence: 99%

Modeling of Electrochemical Hydrogen Storage in Metal Hydride Electrodes

Ledovskikh¹,

Danilov

Vermeulen

et al. 2010

J. Electrochem. Soc.

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The recently presented electrochemical kinetic model, describing the electrochemical hydrogen storage in hydride-forming materials, was extended by the description of the solid/electrolyte interface, i.e., the charge-transfer kinetics and electrical double-layer charging. A complete set of equations was derived, describing the equilibrium hydrogen partial pressure, the equilibrium electrode potential, the exchange current density, and the electrical double-layer capacitance as a function of hydrogen content in both solid-solution and two-phase coexistence regions. The model was applied to simulate isotherms of Pd thin films with nominal thicknesses of 200 and 10 nm. The model demonstrates good agreement between the simulation results and experimental data.

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Thermodynamics and kinetics of the thin film magnesium–hydrogen system

Cited by 24 publications

References 30 publications

Thermodynamic Properties, Hysteresis Behavior and Stress-Strain Analysis of MgH2 Thin Films, Studied over a Wide Temperature Range

Thermodynamic Properties, Hysteresis Behavior and Stress-Strain Analysis of MgH2 Thin Films, Studied over a Wide Temperature Range

Effect of alloying magnesium with chromium and vanadium on hydrogenation kinetics studied with neutron reflectometry

Modeling of Electrochemical Hydrogen Storage in Metal Hydride Electrodes

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