Mechanochemical synthesis and thermal decomposition of Mg(AlH4)2

Kim, Yoonyoung; Lee, Eung Kyu; Shim, Jae Hyeok; Cho, Young Whan; Yoon, Kyung Byung

doi:10.1016/j.jallcom.2005.11.063

Cited by 70 publications

(53 citation statements)

References 21 publications

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“…Simultaneously, the Al content of fcc-Al (blue dotted line) is constant and the Mg content of fcc-Al (blue dashed line) increases smoothly, which proves that Al destabilizes MgH 2 at these temperatures and the resulting Mg atoms dissolve in fcc-Al and increase its amount until the temperature of 234°C, where the solubility limit of Mg in fcc-Al is reached and b forms. This conclusion agrees very well with the XRD results reported in the literature [11,38,39,41], observing the Al peak shift in the MgH 2 /Al composites with increasing temperature until it disappears and the b formation occurs.…”

Section: The Al-mg-h Systemsupporting

confidence: 93%

“…Decomposition of Mg(AlH 4 ) 2 has been investigated by different authors such as Mamatha et al [36] and Varin et al [37] using DSC and Kim et al [38] using TG/MS and DSC, and Iosub et al [39] using XRD, TPD (temperature programmed desorption), and DSC. It has been concluded that magnesium alanate, Mg(AlH 4 ) 2 , decomposes in two steps [38,40] according to the reactions:…”

Section: The Al-mg-h Systemmentioning

confidence: 99%

“…It has been concluded that magnesium alanate, Mg(AlH 4 ) 2 , decomposes in two steps [38,40] according to the reactions:…”

Section: The Al-mg-h Systemmentioning

confidence: 99%

“…These results are in good agreement with the literature. In fact, Palumbo et al [34] calculated a temperature of 230°C for reaction (2), and values in the range 217-240°C have been reported using DSC experiments [36][37][38]. As mentioned in ''AlMg-H system'', Liu et al [41] expressed fcc-Al as Al 0.9-Mg 0.1 in Eq.…”

Section: The Al-mg-h Systemmentioning

confidence: 99%

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Understanding the hydrogen storage behavior of promising Al–Mg–Na compositions using thermodynamic modeling

Abdessameud

Medraj

2016

Mater Renew Sustain Energy

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Thermodynamic modeling of the Al-Mg-Na-H system is performed in this work to understand the phase relationships and reaction mechanisms in this system. The Al-Na system is reassessed using the modified quasichemical model for the liquid phase. All the terminal solid solutions were remodeled using the compound energy formalism. The thermodynamic properties of the ternary systems are estimated from the models of the binary systems and the ternary compound using the CALPHAD method. The reaction pathways for the systems MgH 2 / AlH 3 , MgH 2 /NaAlH 4 , and MgH 2 /Na 3 AlH 6 are calculated and compared to the experimental data from the literature. Details about the reaction mechanisms and temperatures, the amount of the products, and their composition are revealed and discussed in this work. The calculations show that in the composites MgH 2 /NaAlH 4 and MgH 2 /Na 3 AlH 6 , the components spontaneously destabilize mutually in specific relative amounts by forming NaMgH 3 , which may play only a catalytic role on the decomposition of (MgH 2 ? Al) mixture, NaAlH 4 , or Na 3 AlH 6 . Also, Al destabilizes MgH 2 and NaMgH 3 by forming b phase and reducing the decomposition temperatures of these hydrides by more than 50°C. The constructed database is successfully used to reproduce the pressure-composition isotherms (PCIs) for Mg-10 at% Al and Mg-4 at% Al alloys at 350°C. The results provide a better understanding of the reaction mechanisms in the PCIs found in the literature concerning the number of plateau pressures and their sloping. It is shown that the first plateau pressure observed during the PCIs of Al-Mg alloys depends on Al content and is higher than that of pure Mg. This difference is due to Al solubility in hcp-Mg.

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Section: The Al-mg-h Systemsupporting

confidence: 93%

Section: The Al-mg-h Systemmentioning

confidence: 99%

“…It has been concluded that magnesium alanate, Mg(AlH 4 ) 2 , decomposes in two steps [38,40] according to the reactions:…”

Section: The Al-mg-h Systemmentioning

confidence: 99%

Section: The Al-mg-h Systemmentioning

confidence: 99%

See 2 more Smart Citations

Understanding the hydrogen storage behavior of promising Al–Mg–Na compositions using thermodynamic modeling

Abdessameud

Medraj

2016

Mater Renew Sustain Energy

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“…This material has been synthesized previously by ball milling [38] and recently, by molten state processing from the elements and binary hydrides [29]. There is a thermodynamic explanation for this difference; Mg(AlH 4 ) 2 is thermodynamically unstable with respect to the starting materials [38][39][40] while NaMgH 3 has a formation enthalpy of ΔH f = -231 kJ/mol [41]. This formation enthalpy makes NaMgH 3 more thermodynamically stable than MgH 2 and NaH as well.…”

Section: Resultsmentioning

confidence: 99%

Investigation of the thermodynamics governing metal hydride synthesis in the molten state process

Stowe

Berseth

Farrell

et al. 2008

Journal of Alloys and Compounds

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Complex metal hydrides have been synthesized for hydrogen storage through a new synthetic technique utilizing high hydrogen overpressure at elevated temperatures (molten state processing). This synthesis technique holds the potential of fusing different complex hydrides at elevated temperatures and pressures to form new species with enhanced hydrogen storage properties. Formation of these compounds is driven by thermodynamic and kinetic considerations. We report on investigations of the thermodynamics. Novel synthetic complexes were formed, structurally characterized, and their hydrogen desorption properties investigated. The effectiveness of the molten state process is compared with mechanicosynthetic ball milling.

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Improved Hydrogen Storage Properties of Mg(BH₄)₂‐Mg(AlH₄)₂Combined Systems

Xiao¹,

Leng²,

Yu³

et al. 2015

Characterization of Minerals, Metals, and Materials 2015

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Mechanochemical synthesis and thermal decomposition of Mg(AlH4)2

Cited by 70 publications

References 21 publications

Understanding the hydrogen storage behavior of promising Al–Mg–Na compositions using thermodynamic modeling

Understanding the hydrogen storage behavior of promising Al–Mg–Na compositions using thermodynamic modeling

Investigation of the thermodynamics governing metal hydride synthesis in the molten state process

Improved Hydrogen Storage Properties of Mg(BH₄)₂‐Mg(AlH₄)₂Combined Systems

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Mechanochemical synthesis and thermal decomposition of Mg(AlH4)2

Cited by 70 publications

References 21 publications

Understanding the hydrogen storage behavior of promising Al–Mg–Na compositions using thermodynamic modeling

Understanding the hydrogen storage behavior of promising Al–Mg–Na compositions using thermodynamic modeling

Investigation of the thermodynamics governing metal hydride synthesis in the molten state process

Improved Hydrogen Storage Properties of Mg(BH4)2‐Mg(AlH4)2Combined Systems

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Improved Hydrogen Storage Properties of Mg(BH₄)₂‐Mg(AlH₄)₂Combined Systems