Magnesium Hydride of Orthorhombic Crystal from High-Energy Ball Milling under Hydrogen Atmosphere

Zhou, Shi Xue; Wei, Ran; Yang, Min; Wang, De Xi; Chen, Guo Qiang; Zhang, Ye; Han, Zong Ying; Zhang, Qian Qian

doi:10.4028/www.scientific.net/amr.724-725.1033

Cited by 4 publications

(4 citation statements)

References 18 publications

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“…The particle size of the Mg–Ni nanocomposite hydrogenated at 150 °C is about 10–30 nm, which is much smaller than that of MgH 2 prepared by other methods. According to previous studies, the size reduction of MgH 2 could decrease the hydrogen desorption temperature and improve the first hydrogen desorption kinetics. , In addition, γ-MgH 2 phase can destabilize β-MgH 2 and thereby lower the dehydrogenation temperature . Furthermore, Zalusk et al found that the ball-milled mixtures of MgH 2 and Mg 2 NiH 4 exhibited a synergetic effect for the hydrogen desorption .…”

Section: Resultsmentioning

confidence: 95%

“…52,53 In addition, γ-MgH 2 phase can destabilize β-MgH 2 and thereby lower the dehydrogenation temperature. 54 Furthermore, Zalusk et al found that the ball-milled mixtures of MgH 2 and Mg 2 NiH 4 exhibited a synergetic effect for the hydrogen desorption. 55 Those fine Mg 2 NiH 4 particles on the surface of large MgH 2 grains serve as gateways for hydrogen desorption from the interior of the MgH 2 grains.…”

Section: Hydrogen Sorptionmentioning

confidence: 99%

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Hydrogen Storage Properties of a Mg–Ni Nanocomposite Coprecipitated from Solution

et al. 2014

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Reducing Mg particles to nanoscale and doping with various catalysts are considered as efficient approaches for improving the hydrogen storage properties of Mg/MgH 2 . It has been established that doping Ni or Mg 2 Ni into nano-Mg/MgH 2 through physical routes remarkably improves the hydrogen sorption kinetics. In this work, a Mg−Ni nanocomposite has been coprecipitated from a tetrahydrofuran (THF) solution containing anhydrous magnesium chloride (MgCl 2 ), nickel chloride (NiCl 2 ), and lithium naphthalide (LiNp) as the reducing agent. TEM observations reveal that Ni nanoparticles are distributed homogeneously on the surface of those larger Mg particles with sizes ranging from 10 to 20 nm in the nanocomposite. It is observed that γ-MgH 2 phase appears when the nanocomposite is hydrogenated at temperatures below 225°C. Pressure−composition−temperature (PCT) measurements reveal that the Mg−Ni nanocomposite has superior hydrogen storage properties over the pure Mg prepared using the same method. For instance, the Mg−Ni nanocomposite can absorb 85% of its maximum hydrogen capacity within 45 s at 125°C, and a hydrogen capacity of 5.6 wt % can be obtained within 10 h at room temperature. In addition, the dehydrogenation temperature of the hydrogenated Mg−Ni nanocomposite is also much lower than that of the hydrogenated pure Mg. The hydrogenation and dehydrogenation enthalpies of the Mg−Ni nanocomposite are determined to be −70.0 and 70.7 kJ/mol H 2 , slightly lower than those for the reduced pure Mg. The excellent hydrogen sorption properties of the Mg−Ni nanocomposite can be attributed to the nanosize effect of Mg particles and the gateway effect of Mg 2 Ni formed in the composite after hydrogenation/dehydrogenation cycles.

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Section: Resultsmentioning

confidence: 95%

Section: Hydrogen Sorptionmentioning

confidence: 99%

Hydrogen Storage Properties of a Mg–Ni Nanocomposite Coprecipitated from Solution

et al. 2014

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“…The metastable γ-MgH 2 , belonging to a-PbO 2 -type orthorhombic crystal structure, is usually produced by ball milling (Varin et al, 2006;Ponthieu et al, 2013;Zhou et al, 2015) as well as under high compressive stress (Vajeeston et al, 2006;Siviero et al, 2009;Ham et al, 2013). Zhou et al (2013) pointed out that the H octahedrons surrounding Mg atoms are deformed in the γ-MgH 2 . Besides, the octahedral chain takes a zigzag form, while for the β-MgH 2 , the chain is straight.…”

Section: Sample Characterizationmentioning

confidence: 99%

Magnesium Nanoparticles With Pd Decoration for Hydrogen Storage

et al. 2020

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In this work, Magnesium nanoparticles with Pd decoration, ranging from 40 to 70 nm, were successfully coprecipitated from tetrahydrofuran (THF) solution, assigned as the Mg-Pd nanocomposite. The Mg-Pd nanocomposite exhibits superior hydrogen storage properties. For the hydrogenated Mg-Pd nanocomposite at 150 • C, the onset dehydrogenation temperature is significantly reduced to 216.8 • C, with a lower apparent activation energy for dehydrogenation of 93.8 kJ/mol H 2 . High-content γ-MgH 2 formed during the hydrogenation process, along with PH 0.706 , contributes to the enhancing of desorption kinetics. The Mg-Pd nanocomposite can take up 3.0 wt% hydrogen in 2 h at a temperature as low as 50 • C. During lower hydrogenation temperatures, Pd can dissociate hydrogen and create a hydrogen diffusion pathway for the Mg nanoparticles, leading to the decrease of the hydrogenation apparent activation energy (44.3 kJ/mol H 2 ). In addition, the Mg-Pd alloy formed during the hydrogenation/dehydrogenation process can play an active role in the reversible metal hydride transformation, destabilizing the MgH 2 .

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“…Для магния наряду с тет-рагональным гидридом β-MgH 2 известен также мета-стабильный орторомбический гидрид γ-MgH 2 , форми-рующийся из β-MgH 2 при давлениях в несколько ги-гапаскаль или МА в планетарных мельницах [12,13]. При температурах, близких к комнатной в Mg раство-ряется всего около 1 at.% водорода, а растворимость углерода пренебрежимо мала.…”

Section: Introductionunclassified

Дефекты упаковки и механизмы деформационно-индуцированных превращений ГПУ-металлов (Ti, Mg) при механоактивации в жидких углеводородах

Lubnin¹,

Дорофеев²,

Ніконова³

et al. 2017

Физика Твердого Тела

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Методами рентгеновской дифракции, растровой электронной микроскопии и химического анализа исследована эволюция структуры и субструктуры металлов Ti и Mg с гексагональной плотноупакованной (ГПУ) решеткой при их механоактивации в планетарной мельнице в среде жидких углеводородов (толуол, н-гептан), а также с добавками углеродных материалов (графита, фуллерита, нанотрубок). Изучены термическое поведение и водородаккумулирующие свойства получаемых механокомпозитов. При механоактивации Ti и Mg наблюдаются деструкция жидких углеводородов, образование метастабильного нанокристаллического карбогидрида титана Ti(C,H)x и гидрида магния beta-MgH2 соответственно. Механизмы образования Ti(C,H)x и MgH2 при механоактивации являются деформационными и связаны с накоплением дефектов упаковки, образованием гранецентрированной кубической (ГЦК) укладки атомов. Метастабильный Ti(C,H)x распадается при температуре 550oC, происходит частичное обратное превращение ГЦКГПУ. Накопление дефектов кристаллического строения (границ нанозерен, дефектов упаковки), деструкция углеводородов и образование механокомпозитов приводят к ускорению последующего гидрирования магния в реакторе Сивертса. Работа выполнена при финансовой поддержке РФФИ (грант N 16-32-00487) и УрО РАН (N 15-20-2-22). DOI: 10.21883/FTT.2017.11.45063.015

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Magnesium Hydride of Orthorhombic Crystal from High-Energy Ball Milling under Hydrogen Atmosphere

Cited by 4 publications

References 18 publications

Hydrogen Storage Properties of a Mg–Ni Nanocomposite Coprecipitated from Solution

Hydrogen Storage Properties of a Mg–Ni Nanocomposite Coprecipitated from Solution

Magnesium Nanoparticles With Pd Decoration for Hydrogen Storage

Дефекты упаковки и механизмы деформационно-индуцированных превращений ГПУ-металлов (Ti, Mg) при механоактивации в жидких углеводородах

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