A theoretical interpretation of the pressure–composition isotherms of RNi5 (, Pr, Nd and Sm) systems based on statistical mechanics

Senoh, Hiroshi; Takeichi, Nobuhiko; Yasuda, K.; Kiyobayashi, Tetsu

doi:10.1016/j.jallcom.2008.02.065

Cited by 8 publications

(4 citation statements)

References 22 publications

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“…P–c isotherms with multiple plateaus have been previously reported for the A Ni 5 system. − Senoh et al measured P–c isotherms for A Ni 5 ( A = La, Pr, Nd, Sm, and Gd) at different temperatures . For Pr, Nd, Sm, and Gd, they observed two plateaus and noticed that the gap between them diminishes with increasing temperature.…”

Section: Discussionmentioning

confidence: 81%

Structural and Hydrogen Storage Properties of Y₂Ni₇ Deuterides Studied by Neutron Powder Diffraction

et al. 2015

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The crystal structure and hydrogenation properties of Gd2Co7-type Y2Ni7 were investigated by X-ray diffraction (XRD), Sievert’s method, and neutron powder diffraction. Unlike Nd2Ni7 and La2Ni7, Y2Ni7 exhibits three plateau pressures and forms three hydrides at room temperature. The maximum hydrogen capacity reaches 8.9 H/fu at 10 MPa at the first absorption cycle. The compound can be cycled by a solid–gas route, and structural properties are fully recovered after dehydrogenation. For the first time, the structural properties of rhombohedral A 2 B 7D x deuterides were studied. They were investigated by neutron powder diffraction at three different states of charge (x = 2.1, 4.1, and 8.8). Deuterium positions as well as variation of unit cell parameters are given and discussed in this paper.

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Section: Discussionmentioning

confidence: 81%

Structural and Hydrogen Storage Properties of Y₂Ni₇ Deuterides Studied by Neutron Powder Diffraction

et al. 2015

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“…To model the behaviour of real systems and wider MH alloys, this model has been progressively extended by other researchers 17‐19 . Meanwhile, contributions were made in the application of statistical physics for the description of phase equilibria in metal‐hydrogen systems 20‐22 . For the plateau region in a PCT model, the variation of the plateau pressure with hydrogen concentration was introduced to ensure that hydrogen equilibrium pressure was obtained as a convolution of an ideal flat‐plateau isotherm with a function similar to a Gaussian distribution density 23 .…”

Section: Introductionmentioning

confidence: 99%

“…[17][18][19] Meanwhile, contributions were made in the application of statistical physics for the description of phase equilibria in metal-hydrogen systems. [20][21][22] For the plateau region in a PCT model, the variation of the plateau pressure with hydrogen concentration was introduced to ensure that hydrogen equilibrium pressure was obtained as a convolution of an ideal flat-plateau isotherm with a function similar to a Gaussian distribution density. 23 It was then expanded by the combination of a regular interstitial hydrogen solution model for the αand β-phases of H 2 -M system with the Gaussian distribution model for the hydrogen equilibrium pressures in the sloping plateau region.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of pressure‐concentration‐temperature profiles for metal hydride hydrogen storage alloys with model development

2023

Energy Storage

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Metal hydride (MH) alloys have been applied to hydrogen storage and various energy conversion systems such as refrigeration, heat pump and heat transformer. However, to facilitate and efficiently investigate efficiently a particular application, an MH alloy must firstly be characterised with a purposely built test facility to measure profiles of pressure, MH hydrogen concentration and temperature (PCT). Obtaining detailed PCT profiles or curves could be an arduous and expensive task as each isothermal hydrogen absorption or desorption line requires hundreds of measurement points. It is thus desirable to develop an accurate correlative model for the PCT profiles with limited measurements of thermophysical property data for the purpose of characterisation of each MH alloy. This correlative model or characterisation process has been developed and is described in detail in this article. The correlative PCT MH alloy profiles can cover all applicable hydrogen storage phase regions of α, α + β and β as well as the phase transition dome curve and critical point such that a PCT phase diagram for a particular MH alloy can be depicted and characterised. As an application example, the correlative model is applied to predict an MH alloy's hydrogen storage capacity and hysteresis at a specific MH temperature. It has been discovered that each of these two parameters shows comparative trends in variation with reduced temperature. Correspondingly, for each parameter, a correlative function with reduced temperature has been produced. The MH alloy characterisation process is an essential step towards a detailed dynamic MH energy system modelling, simulation and optimisation as well as experimental investigation.

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“…Later, Beeri et al [14][15][16] revised the Lacher-type model by applying Bragg-Williams and the Quasi-Chemical approximations and derived the PCI curves, considering the situations of real gas and the existence of multiple plateaus. Senoh et al [17] interpreted the PCI curves theoretically based on statistical mechanics, in which the RNi 5 (R = La, Pr, Nd and Sm)-H was regarded as a grand canonical ensemble. Lexcellent et al [18] modeled the anhysteretic PCI curves, discussed the plateau or slope in detail, and finally applied it in the La-Ni-based alloys.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic and Kinetic Properties of La20.5MgNi78.5 and La15.5Mg6Ni78.5 Hydrogen Storage Alloys: The Theoretical Models and Their Verifications

An¹,

Pang²,

Li³

et al. 2016

Int J Metall Mater Eng

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In this paper, we present a statistic thermodynamic model quantitatively describing the pressurecomposition-isotherms (PCI) curve, which consists of hydrogen storage capacity, temperature, and equilibrium pressure in the hydriding and dehydriding (H/D) reactions, and a theoretical kinetic model to clarify the H/D kinetic mechanism of hydrogen storage alloys. The results of the calculations are well agreed with the experiments performed with La 20.5 MgNi 78.5 and La1 5.5 Mg 6 Ni 78.5 alloys, their maximum hydrogen storage capacities and the hydride formation enthalpies at 303~333 K are 1.41 wt.% H 2 and -31.64 kJ/mol H 2 for La 20.5 MgNi 78.5 and 1.31 wt.% H 2 and -27.23 kJ/mol H 2 for La1 5.5 Mg 6 Ni 78.5 , respectively. A new diffusion kinetic model is proposed with the consideration of Pilling-Bedworth Ratio, i.e. hydrogen-induced volume change used for studying the hydrogen absorption reaction kinetics. The activation energies are calculated to be 31.25 kJ/mol H 2 for La 20.5 MgNi 78.5 and 24.24 kJ/mol H 2 for La1 5.5 Mg 6 Ni 78.5 , respectively.

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A theoretical interpretation of the pressure–composition isotherms of RNi5 (, Pr, Nd and Sm) systems based on statistical mechanics

Cited by 8 publications

References 22 publications

Structural and Hydrogen Storage Properties of Y₂Ni₇ Deuterides Studied by Neutron Powder Diffraction

Structural and Hydrogen Storage Properties of Y₂Ni₇ Deuterides Studied by Neutron Powder Diffraction

Characterisation of pressure‐concentration‐temperature profiles for metal hydride hydrogen storage alloys with model development

Thermodynamic and Kinetic Properties of La20.5MgNi78.5 and La15.5Mg6Ni78.5 Hydrogen Storage Alloys: The Theoretical Models and Their Verifications

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A theoretical interpretation of the pressure–composition isotherms of RNi5 (, Pr, Nd and Sm) systems based on statistical mechanics

Cited by 8 publications

References 22 publications

Structural and Hydrogen Storage Properties of Y2Ni7 Deuterides Studied by Neutron Powder Diffraction

Structural and Hydrogen Storage Properties of Y2Ni7 Deuterides Studied by Neutron Powder Diffraction

Characterisation of pressure‐concentration‐temperature profiles for metal hydride hydrogen storage alloys with model development

Thermodynamic and Kinetic Properties of La20.5MgNi78.5 and La15.5Mg6Ni78.5 Hydrogen Storage Alloys: The Theoretical Models and Their Verifications

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Structural and Hydrogen Storage Properties of Y₂Ni₇ Deuterides Studied by Neutron Powder Diffraction

Structural and Hydrogen Storage Properties of Y₂Ni₇ Deuterides Studied by Neutron Powder Diffraction