Special Issue "Properties and Applications of Novel Light Metal Hydrides"

A special issue of Crystals (ISSN 2073-4352).

Deadline for manuscript submissions: closed (20 March 2018)

Special Issue Editors

Guest Editor
Prof. Dr. Radovan Cerny

Université de Genève, Department of Quantum Matter Physics, Genève, Switzerland
Website | E-Mail
Guest Editor
Prof. Dr. Yaroslav Filinchuk

Universite Catholique de Louvain, Louvain-la-Neuve, Belgium
Website | E-Mail
Phone: +32 10 47 28 13
Interests: hydrides, in situ diffraction, porous solids, functional materials

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

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1200 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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Open AccessArticle Direct Rehydrogenation of LiBH4 from H-Deficient Li2B12H12−x
Crystals 2018, 8(3), 131; https://doi.org/10.3390/cryst8030131
Received: 22 January 2018 / Revised: 23 February 2018 / Accepted: 6 March 2018 / Published: 9 March 2018
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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
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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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Open AccessFeature PaperArticle Synthesis, Crystal Structure Analysis and Decomposition of RbAlH4
Crystals 2018, 8(2), 103; https://doi.org/10.3390/cryst8020103
Received: 31 January 2018 / Revised: 16 February 2018 / Accepted: 21 February 2018 / Published: 22 February 2018
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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
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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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Open AccessArticle Mg2FeH6 Synthesis Efficiency Map
Crystals 2018, 8(2), 94; https://doi.org/10.3390/cryst8020094
Received: 19 January 2018 / Revised: 5 February 2018 / Accepted: 7 February 2018 / Published: 11 February 2018
Cited by 1 | PDF Full-text (1419 KB) | HTML Full-text | XML Full-text | Supplementary Files
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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Graphical abstract

Open AccessArticle Reactive Hydride Composite of Mg2NiH4 with Borohydrides Eutectic Mixtures
Crystals 2018, 8(2), 90; https://doi.org/10.3390/cryst8020090
Received: 20 January 2018 / Revised: 6 February 2018 / Accepted: 7 February 2018 / Published: 10 February 2018
Cited by 1 | PDF Full-text (2544 KB) | HTML Full-text | XML Full-text
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
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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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Open AccessArticle Crystal Structural Determination of SrAlD5 with Corner-Sharing AlD6 Octahedron Chains by X-ray and Neutron Diffraction
Crystals 2018, 8(2), 89; https://doi.org/10.3390/cryst8020089
Received: 17 January 2018 / Revised: 5 February 2018 / Accepted: 7 February 2018 / Published: 9 February 2018
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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
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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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Open AccessReview The Effects of Nanostructure on the Hydrogen Sorption Properties of Magnesium-Based Metallic Compounds: A Review
Crystals 2018, 8(2), 106; https://doi.org/10.3390/cryst8020106
Received: 27 January 2018 / Revised: 19 February 2018 / Accepted: 21 February 2018 / Published: 23 February 2018
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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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