Properties and Applications of Novel Light Metal Hydrides

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Inorganic Crystalline Materials".

Deadline for manuscript submissions: closed (20 March 2018) | Viewed by 26662

Special Issue Editors


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Guest Editor
Université de Genève, Department of Quantum Matter Physics, Genève, Switzerland

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Guest Editor
Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
Interests: synthesis and characterization of inorganic materials; structural, chemical and physical properties; synchrotron and neutron diffraction
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Special Issue Information

Dear Colleagues,

Metal hydrides form a broad spectrum of chemical compounds. From interstitial hydrides, through complex hydrides to chemical hydrides. Their applications include hydrogen storage, magnetic materials, ionic conductors, phosphors, reducing agents in organic syntheses. Using lighter metals increases the hydrogen storage weight capacity and shifts the metal-hydrogen interaction towards covalent bond.

The Special Issue on “Properties and Applications of Novel Light Metal Hydrides” is intended to provide a unique international forum aimed at covering a broad description of results involving essential hydrides synthesis, characterization and study of properties as well as various applications. Scientists working in a wide range of disciplines are invited to contribute to this cause.

The topics summarized under the keywords cover broadly examples of the greater number of sub-topics in mind. The volume is especially open for any innovative contributions involving crystal design aspect.

Prof. Dr. Radovan Cerny
Prof. Dr. Yaroslav Filinchuk
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Hydrogen storage
  • Solid electrolytes
  • Magnetism
  • High pressures
  • Superconductivity
  • Crystal structure
The first round submission deadline: 20 January 2018.

Published Papers (6 papers)

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Research

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7 pages, 785 KiB  
Article
Direct Rehydrogenation of LiBH4 from H-Deficient Li2B12H12−x
by Yigang Yan, Hui Wang, Min Zhu, Weitong Cai, Daniel Rentsch and Arndt Remhof
Crystals 2018, 8(3), 131; https://doi.org/10.3390/cryst8030131 - 09 Mar 2018
Cited by 13 | Viewed by 4161
Abstract
Li2B12H12 is commonly considered as a boron sink hindering the reversible hydrogen sorption of LiBH4. Recently, in the dehydrogenation process of LiBH4 an amorphous H-deficient Li2B12H12−x phase was observed. In [...] Read more.
Li2B12H12 is commonly considered as a boron sink hindering the reversible hydrogen sorption of LiBH4. Recently, in the dehydrogenation process of LiBH4 an amorphous H-deficient Li2B12H12−x phase was observed. In the present study, we investigate the rehydrogenation properties of Li2B12H12−x to form LiBH4. With addition of nanostructured cobalt boride in a 1:1 mass ratio, the rehydrogenation properties of Li2B12H12−x are improved, where LiBH4 forms under milder conditions (e.g., 400 °C, 100 bar H2) with a yield of 68%. The active catalytic species in the reversible sorption reaction is suggested to be nonmetallic CoxB (x = 1) based on 11B MAS NMR experiments and its role has been discussed. Full article
(This article belongs to the Special Issue Properties and Applications of Novel Light Metal Hydrides)
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9 pages, 3797 KiB  
Article
Synthesis, Crystal Structure Analysis and Decomposition of RbAlH4
by Claudia Weidenthaler, Michael Felderhoff, Thomas Bernert, Magnus H. Sørby, Bjørn C. Hauback and Daniel Krech
Crystals 2018, 8(2), 103; https://doi.org/10.3390/cryst8020103 - 22 Feb 2018
Cited by 4 | Viewed by 4092
Abstract
RbAlH4, a member of the complex metal aluminum hydride family, can be synthesized phase pure by different synthesis routes. Synthesis from the metals by a mechanochemical reaction requires the presence of a catalyst, but also emphasizes the reversibility of hydrogenation. The [...] Read more.
RbAlH4, a member of the complex metal aluminum hydride family, can be synthesized phase pure by different synthesis routes. Synthesis from the metals by a mechanochemical reaction requires the presence of a catalyst, but also emphasizes the reversibility of hydrogenation. The structure refinement of neutron diffraction data confirms that RbAlD4 is isostructural to KAlD4. The decomposition proceeds via two distinct processes at temperatures above 275 °C. However, the structures formed during decomposition seem to be different from the compounds formed during hydrogen release of early alkali metal aluminum hydrides. Full article
(This article belongs to the Special Issue Properties and Applications of Novel Light Metal Hydrides)
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12 pages, 1419 KiB  
Article
Mg2FeH6 Synthesis Efficiency Map
by Katarzyna Witek, Krzysztof Karczewski, Magdalena Karpowicz and Marek Polanski
Crystals 2018, 8(2), 94; https://doi.org/10.3390/cryst8020094 - 11 Feb 2018
Cited by 18 | Viewed by 4138
Abstract
The influences of the processing parameters on the Mg2FeH6 synthesis yield were studied. Mixtures of magnesium hydride (MgH2) and iron (Fe) were mechanically milled in a planetary ball mill under argon for 0.5-, 1-, 2- and 3-h periods [...] Read more.
The influences of the processing parameters on the Mg2FeH6 synthesis yield were studied. Mixtures of magnesium hydride (MgH2) and iron (Fe) were mechanically milled in a planetary ball mill under argon for 0.5-, 1-, 2- and 3-h periods and subsequently sintered at temperatures from 300–500 C under hydrogen. The reaction yield, phase content and hydrogen storage properties of the received materials were investigated. The morphologies of the powders after synthesis were studied by SEM. The synthesis effectiveness map was presented. The obtained results prove that synthesis parameters, such as the milling time and synthesis temperature, greatly influence the reaction yield and material properties and show that extended mechanical milling may not be beneficial to the reaction efficiency. Full article
(This article belongs to the Special Issue Properties and Applications of Novel Light Metal Hydrides)
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12 pages, 2544 KiB  
Article
Reactive Hydride Composite of Mg2NiH4 with Borohydrides Eutectic Mixtures
by Erika M. Dematteis, Silvère Vaunois, Claudio Pistidda, Martin Dornheim and Marcello Baricco
Crystals 2018, 8(2), 90; https://doi.org/10.3390/cryst8020090 - 10 Feb 2018
Cited by 14 | Viewed by 4814
Abstract
The development of materials showing hydrogen sorption reactions close to room temperature and ambient pressure will promote the use of hydrogen as energy carrier for mobile and stationary large-scale applications. In the present study, in order to reduce the thermodynamic stability of MgH [...] Read more.
The development of materials showing hydrogen sorption reactions close to room temperature and ambient pressure will promote the use of hydrogen as energy carrier for mobile and stationary large-scale applications. In the present study, in order to reduce the thermodynamic stability of MgH2, Ni has been added to form Mg2NiH4, which has been mixed with various borohydrides to further tune hydrogen release reactions. De-hydrogenation/re-hydrogenation properties of Mg2NiH4-LiBH4-M(BH4)x (M = Na, K, Mg, Ca) systems have been investigated. Mixtures of borohydrides have been selected to form eutectics, which provide a liquid phase at low temperatures, from 110 °C up to 216 °C. The presence of a liquid borohydride phase decreases the temperature of hydrogen release of Mg2NiH4 but only slight differences have been detected by changing the borohydrides in the eutectic mixture. Full article
(This article belongs to the Special Issue Properties and Applications of Novel Light Metal Hydrides)
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9 pages, 1831 KiB  
Article
Crystal Structural Determination of SrAlD5 with Corner-Sharing AlD6 Octahedron Chains by X-ray and Neutron Diffraction
by Toyoto Sato, Shigeyuki Takagi, Magnus H. Sørby, Stefano Deledda, Bjørn C. Hauback and Shin-ichi Orimo
Crystals 2018, 8(2), 89; https://doi.org/10.3390/cryst8020089 - 09 Feb 2018
Cited by 5 | Viewed by 3528
Abstract
Aluminium-based complex hydrides (alanates) composed of metal cation(s) and complex anion(s), [AlH4] or [AlH6]3− with covalent Al–H bonds, have attracted tremendous attention as hydrogen storage materials since the discovery of the reversible hydrogen desorption and absorption reactions [...] Read more.
Aluminium-based complex hydrides (alanates) composed of metal cation(s) and complex anion(s), [AlH4] or [AlH6]3− with covalent Al–H bonds, have attracted tremendous attention as hydrogen storage materials since the discovery of the reversible hydrogen desorption and absorption reactions on Ti-enhanced NaAlH4. In cases wherein alkaline-earth metals (M) are used as a metal cation, MAlH5 with corner-sharing AlH6 octahedron chains are known to form. The crystal structure of SrAlH5 has remained unsolved although two different results have been theoretically and experimentally proposed. Focusing on the corner-sharing AlH6 octahedron chains as a unique feature of the alkaline-earth metal, we here report the crystal structure of SrAlD5 investigated by synchrotron radiation powder X-ray and neutron diffraction. SrAlD5 was elucidated to adopt an orthorhombic unit cell with a = 4.6226(10) Å, b = 12.6213(30) Å and c = 5.0321(10) Å in the space group Pbcm (No. 57) and Z = 4. The Al–D distances (1.77–1.81 Å) in the corner-sharing AlD6 octahedra matched with those in the isolated [AlD6]3− although the D–Al–D angles in the penta-alanates are significantly more distorted than the isolated [AlD6]3−. Full article
(This article belongs to the Special Issue Properties and Applications of Novel Light Metal Hydrides)
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Review

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28 pages, 7765 KiB  
Review
The Effects of Nanostructure on the Hydrogen Sorption Properties of Magnesium-Based Metallic Compounds: A Review
by Luca Pasquini
Crystals 2018, 8(2), 106; https://doi.org/10.3390/cryst8020106 - 23 Feb 2018
Cited by 34 | Viewed by 5150
Abstract
In this review, I examine the influence of nanoscale materials features on the hydrogen-metal interaction. The small system size, the abundance of surfaces/interfaces, and the spatial distribution of phases are the key factors to understand the hydrogen sorption properties of nanomaterials. In order [...] Read more.
In this review, I examine the influence of nanoscale materials features on the hydrogen-metal interaction. The small system size, the abundance of surfaces/interfaces, and the spatial distribution of phases are the key factors to understand the hydrogen sorption properties of nanomaterials. In order to describe nanoscale-specific thermodynamic changes, I present a quantitative model applicable to every hydride-forming material, independently on its composition and atomic structure. The effects of surface free energy, interface free energy, and elastic constraint, are included in a general expression for the thermodynamical bias. In the frame of this model, I critically survey theoretical and experimental results hinting at possible changes of thermodynamic parameters, and in particular, enthalpy and entropy of hydride formation, in nanostructured Mg-based metallic compounds as compared to their coarse-grained bulk counterparts. I discuss the still open controversies, such as destabilization of ultra-small clusters and enthalpy–entropy compensation. I also highlight the frequently missed points in experiments and data interpretation, such as the importance of recording full hydrogen absorption and desorption isotherms and of measuring the hysteresis. Finally, I try to address the open questions that may inspire future research, with the ambition of tailoring the properties of hydride nanomaterials through a deeper understanding of their thermodynamics. Full article
(This article belongs to the Special Issue Properties and Applications of Novel Light Metal Hydrides)
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