The Effect of Alloying of Palladium on the Hydrogen-Palladium Miscibility Gap

Sakamoto, Y.; Baba, Kensuke; Flanagan, Ted B.

doi:10.1524/zpch.1988.158.part_2.223

Cited by 74 publications

(49 citation statements)

References 38 publications

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“…However, the tendencies shown in Fig. 7 are qualitatively similar to the trends in the limiting values of lattice parameters for the α-and β-phase boundaries reported earlier in the literature [11], where it is demonstrated that for Pd-Rh alloys containing at least 20% Rh the β phase of absorbed hydrogen can be formed.…”

Section: Resultssupporting

confidence: 88%

“…The potential of the α→β phase transition for Pd-Rh alloys is lower than for pure Pd, which means that under gas phase conditions the corresponding hydrogen pressure is higher. The shift of the potential (pressure) corresponding to the phase transition is explained by the geometric effect, i.e., changes in the dimensions of the unit cell after alloy formation [11,[42][43][44][45]. In general, for most of the Pd alloys of a lattice constant higher than that of pure Pd (expanded systems) an increase in potential (decrease in pressure) is observed for the phase transition due to the fact that the work needed to increase the dimensions of the crystal lattice during the β phase formation is smaller.…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, in the case of alloys with a lattice constant lower than pure Pd (contracted systems) there is a need for an additional work connected with the increasing size of the crystal lattice during hydrogen absorption in the β phase, which is mirrored in a decrease in potential (increase in pressure) for the phase transition. Pd-Rh alloys belong to the second group of systems [11]. However, more recent DFT calculations suggest that the influence of the electronic structure is even more important than the effect of the lattice constant to explain the variation in absorbed hydrogen stability in Pd alloys [46].…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, the composition range where two phases of absorbed hydrogen can coexist also seems to be greater than for other Pd alloys [9,11]. Crystallographic data [11] indicate that the β phase can be formed at least up to 20% Rh in the bulk. Our earlier results [9] suggest that at room temperature the second phase in the Pd-Rh-H ternary system exists up to ca.…”

Section: Introductionmentioning

confidence: 85%

“…20% Rh can still absorb high amounts of hydrogen [9,10]. Moreover, the composition range where two phases of absorbed hydrogen can coexist also seems to be greater than for other Pd alloys [9,11]. Crystallographic data [11] indicate that the β phase can be formed at least up to 20% Rh in the bulk.…”

Section: Introductionmentioning

confidence: 97%

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Influence of rhodium additive on hydrogen electrosorption in palladium-rich Pd–Rh alloys

Koss

Łukaszewski

Hubkowska

et al. 2011

J Solid State Electrochem

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Hydrogen electrosorption into Pd-rich (>80 at.% Pd in the bulk) Pd-Rh alloys has been studied in acidic solutions (0.5 M H 2 SO 4 ) using cyclic voltammetry and chronoamperometry. The influence of temperature (in the range between 283 and 328 K), electrode potential and alloy bulk composition on hydrogen electrosorption properties of Pd-Rh alloys is presented. It has been found that the additive of Rh to Pd-Rh alloys increases the maximum hydrogen solubility (for Rh bulk content below 10 at.%), decreases the potential of absorbed hydrogen oxidation peak and decreases the potential of the α→β phase transition. Increasing temperature decreases the potential of absorbed hydrogen oxidation peak, the maximum hydrogen solubility, and the potential of the α→β phase transition. The amounts of electrosorbed hydrogen for α-and β-phase boundaries, i.e., α max and β min , have been determined from the integration of the initial parts of current-time responses in hydrogen absorption and desorption processes. The H/M ratio corresponding to α max increases with increasing Rh content, while for β min a maximum of H/M ratio is observed for the alloys containing ca. 95% Rh.

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 97%

See 3 more Smart Citations

Influence of rhodium additive on hydrogen electrosorption in palladium-rich Pd–Rh alloys

Koss

Łukaszewski

Hubkowska

et al. 2011

J Solid State Electrochem

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Towards Designing Stable Pd‐Based Membranes for Hydrogen Gas Separation: A Statistical Thermodynamics Approach

Nanu¹,

Böttger²

2008

Adv Funct Materials

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A method to design new, not yet synthesized, multicomponent alloys based on knowledge of binary alloys is applied to develop Pd‐alloys for membranes for gas separation. The approach couples the cluster variation method with effective pair potentials to describe the phase boundaries between the α‐solid solution (low hydrogen content) and β‐hydride phases. The calculations illustrate (i) that the method can predict α − β phase boundaries of hydrogen in binary and ternary Pd‐alloys, (ii) how the relative interaction strengths of filled and empty interstitial sites influence the width of the miscibility gap, (iii) that the hydrogen absorption capacity of an alloy is related to the hydride phase stability and (iv) the presence of short range order of hydrogen in β‐hydrides.

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Thermodynamic Studies of the Absorption of Hydrogen by Pd – Ti(Zr) Solid Solution Alloys

Sakamoto

Miyagawa

Hamamoto

et al. 1990

Ber Bunsenges Phys Chem

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The solubility of hydrogen in Pd – Ti and Pd – Zr solid solution alloys containing up to 6.0 at.% Ti and Zr has been measured at temperatures between 273 K and 433 K and hydrogen pressures up to 1000 Torr. The relative partial molar enthalpy, ΔH0H, at infinite dilution for Pd – Ti alloys shows a minor minimum around 4 at.% Ti, in spite of the Pd lattice contraction on Ti substitution. For Pd – Zr alloys the ΔH0H values increase in exothermicity regularly with Zr content. The relative partial molar entropy, ΔS0H, at infinite dilution in both alloy series decreases with the solute contents. The apparent H‐H attractive interactions, g1, in Pd – Ti(Zr) alloys decrease with alloying metal content, and the trend of the g1 value with Ti content is dissimilar to those found for other lattice contracted alloys. The stability of the β‐phase hydride in Pd – Ti alloys decreases with Ti content and the β‐phase hydride in Pd – Zr alloys also becomes less stable with Zr content, albeit by a small amount, despite being a lattice expanded alloy system. Solvus compositions at the αmax phase boundary in both Pd – Ti and Pd – Zr alloys are almost equal at the same alloying compositions of each alloy series, although increasing with alloying metal content in both cases.

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The Effect of Alloying of Palladium on the Hydrogen-Palladium Miscibility Gap

Cited by 74 publications

References 38 publications

Influence of rhodium additive on hydrogen electrosorption in palladium-rich Pd–Rh alloys

Influence of rhodium additive on hydrogen electrosorption in palladium-rich Pd–Rh alloys

Towards Designing Stable Pd‐Based Membranes for Hydrogen Gas Separation: A Statistical Thermodynamics Approach

Thermodynamic Studies of the Absorption of Hydrogen by Pd – Ti(Zr) Solid Solution Alloys

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