| 1. |
- Churchard, A. J., et al.
(författare)
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A multifaceted approach to hydrogen storage
- 2011
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 13:38, s. 16955-16972
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Tidskriftsartikel (refereegranskat)abstract
- The widespread adoption of hydrogen as an energy carrier could bring significant benefits, but only if a number of currently intractable problems can be overcome. Not the least of these is the problem of storage, particularly when aimed at use onboard light-vehicles. The aim of this overview is to look in depth at a number of areas linked by the recently concluded HYDROGEN research network, representing an intentionally multi-faceted selection with the goal of advancing the field on a number of fronts simultaneously. For the general reader we provide a concise outline of the main approaches to storing hydrogen before moving on to detailed reviews of recent research in the solid chemical storage of hydrogen, and so provide an entry point for the interested reader on these diverse topics. The subjects covered include: the mechanisms of Ti catalysis in alanates; the kinetics of the borohydrides and the resulting limitations; novel transition metal catalysts for use with complex hydrides; less common borohydrides; protic-hydridic stores; metal ammines and novel approaches to nano-confined metal hydrides.
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| 2. |
- Kravtsov, E, et al.
(författare)
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Fine-tuning of the spin-density-wave state in Cr/V heterostructures via hydrogen uptake
- 2009
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 21:33, s. 336004-
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Tidskriftsartikel (refereegranskat)abstract
- We show that the magnetic state in rather thick Cr films can be finely tuned via hydrogen uptake into adjacent vanadium layers at rather low hydrogen pressures. By changing the hydrogen concentration and, hence, the electronic structure in the V layers, it is possible to affect the global properties of spin-density waves (SDWs) in Cr layers, including the SDW period and the Neel temperature. We provide direct experimental evidence that hydrogen uptake into V layers can be used to switch between incommensurate and commensurate SDW states in a reproducible way.
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| 3. |
- Kravtsov, Evgeny, et al.
(författare)
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Onset of spin-density-wave antiferromagnetism in Cr/V multilayers
- 2007
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 76:2, s. 024421-
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Tidskriftsartikel (refereegranskat)abstract
- Spin-density-wave (SDW) magnetism in a series of Cr/V heterostructures with different Cr thicknesses was systematically investigated by combined resistivity, neutron, and synchrotron scattering measurements. We show that the onset of the bulklike SDW state comes through several necessary steps from a paramagnetic state through a commensurate SDW to an incommensurate SDW. The Néel temperature for the incommensurate SDW is found to scale with Cr thickness and reaches the bulk value at a Cr thickness of about 2000 Å. The proximity effect from Cr/V interfaces is found to lead to (i) the appearance of a 50-Å magnetically dead Cr layer near Cr/V interfaces and (ii) suppression of the spin-flip transition and stabilization of a single-domain SDW with out-of-plane spins and out-of-plane propagation wave vector. Finally, we show that the SDW period increases with decreasing Cr thickness and becomes temperature independent in sufficiently thin Cr layers.
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Remhof, A., et al.
(författare)
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Hydrogen Functionalized Materials
- 2008
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Ingår i: Hydrogen as a Future Energy Carrier. - Weinheim : Verlag GmbH & Co. KGaA. - 9783527308170
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Remhof, A., et al.
(författare)
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Stability of the induced magnetic V moment in Fe/V superlattices upon hydrogen loading
- 2007
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Ingår i: Superlattices and Microstructures. - : Elsevier BV. - 0749-6036 .- 1096-3677. ; 41:2-3, s. 127-131
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Tidskriftsartikel (refereegranskat)abstract
- We report on the stability of the V magnetic moment within Fe/V superlattices upon H-uptake. At the Fe/V interface V atoms acquire a magnetic moment, antiparallel aligned to the Fe moments. Upon hydrogen loading the saturation magnetization was found to increase. We utilized element specific X-ray resonant magnetic scattering to address the response of the induced V moments. An epitaxial [Fe(5ML)/V (16ML)]×30 superlattice was employed. The soft x-ray measurements were carried out using the ALICE diffractometer at BESSY II in Berlin, Germany. The data clearly show the stability of the V moment upon H-loading. No change of the magnetic asymmetry at the V edge could be recognized. Our measurements confirm ab-initio calculations predicting a stable V moment and an increase of the Fe moment in H loaded Fe/V superlattices.
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| 9. |
- Remhof, A., et al.
(författare)
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Remote control of the Fe magnetic moment in magnetic heterostructures
- 2007
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 79:3, s. 37003-
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Tidskriftsartikel (refereegranskat)abstract
- In magnetic superlattices with interlayer exchange coupling, not only the coupling strength but also the magnetic moment of the ferromagnetic layer can be altered non-locally by modifying the electronic structure of the non-magnetic spacer layer. Specifically, changes of the electronic structure of the V spacer layers in Fe/V (001) superlattices are seen to affect the adjacent Fe layers. By reversibly loading the V layer with hydrogen, the magnetic moment of Fe increases, whereas the induced magnetic moment in V remains unchanged. The nature of this remote and non-local control of the magnetic moment is connected with a d-electron charge transfer and effective shift of the Fermi level relative to the d-bands of Fe and V, as elucidated on the basis of self-consistent electronic structure calculations.
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| 10. |
- Uzdin, M, et al.
(författare)
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Transition from spin-density-wave to layered antiferromagnetic state induced by hydrogen as a test for the origin of spin-density waves in chromium
- 2009
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 80:17, s. 174418-
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Tidskriftsartikel (refereegranskat)abstract
- Neutron scattering experiments of Cr/V(001) superlattices are discussed, which show that the incommensurate spin-density-wave (SDW) in thick Cr layers becomes suppressed when the V spacer layers are loaded with hydrogen. The hydrogen loading triggers a transition from the incommensurate SDW state to a commensurate antiferromagnetic state. Model Hamiltonian calculations are presented, which show that this transition is not connected with the nesting property of the Cr Fermi surface. Instead, the transition is a manifestation of the antiferromagnetic ground state of Cr, which is separated from the incommensurate SDW state by an energy barrier. Hydrogen is identified as an effective trigger for reducing the activation barrier, enabling the system to relax to the ground state.
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