Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1234 Structural Basis for Hydrogen Interaction in Selected Metal Hydrides JONAS ÅNGSTRÖM ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 ISBN 978-91-554-9187-1 UPPSALA urn:nbn:se:uu:diva-245046 2015 Dissertation presented at Uppsala University to be publicly examined in Häggsalen, Ångströmlaboratoriet Lägerhyddsvägen 1, Uppsala, Friday, 24 April 2015 at 09:15 for the degree of Doctor of Philosophy. The examination will be conducted in English. Faculty examiner: Fermin Cuevas (East Paris Institute of Chemistry and Materials Science, CNRS). Abstract Ångström, J. 2015. Structural Basis for Hydrogen Interaction in Selected Metal Hydrides. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1234. 74 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-554-9187-1. Metal hydrides have existing and potential uses in many applications such as in batteries, for hydrogen storage and for heat storage. New metal hydrides and a better understanding of the behaviour of known metal hydrides may prove crucial in the realisation or further development of these applications. The aims of the work described in this thesis have been to characterise new metal hydrides, investigate how the properties of known metal hydrides can be improved and understand how their structure influences these properties. Metal hydrides, in most cases synthesised via high-temperature techniques, were structurally characterised using X-ray powder diffraction, X-ray single crystal diffraction and neutron powder diffraction and their thermodynamic and kinetic properties by in-situ X-ray powder diffraction, thermal desorption spectroscopy and pressure-composition-temperature measurements. The investigations showed that: the storage capacity of the hexagonal Laves phase Sc(Al1- xNix)2 decreases with increasing Al content. There is a significant decrease in the stability of the hydrides and faster reaction kinetics when Zr content is increased in the cubic Laves phase Sc1- xZrx(Co1-xNix)2. Nb4M0.9Si1.1 (M=Co, Ni) form very stable interstitial hydrides which have very slow sorption kinetics. MgH2 mixed with 10 mol% ScH2 reaches full activation after only one cycle at 673 K while it takes at least four cycles at 593 K. LnGa (Ln=Nd, Gd) absorb hydrogen in two steps, it is very likely that the first step is interstitial solution of hydride ions into Ln4 tetrahedra and the second step places hydrogen atoms in Ln3Ga tetrahedra. The nature of the Ga-H bond is still unclear. Jonas Ångström, Department of Chemistry - Ångström, Box 523, Uppsala University, SE-75120 Uppsala, Sweden. © Jonas Ångström 2015 ISSN 1651-6214 ISBN 978-91-554-9187-1 urn:nbn:se:uu:diva-245046 (http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-245046) “Jag känner mig däremot såsom transformist nästan förpliktigad antaga endast ett enkelt ämne, ur vilket de andra genom förtunning, förtätning, kopulation, korsning och så vidare uppståt, och detta utan att vilja nämna ur-ämnet vid namn, kanske inte en gång vid namnet väte.” August Strindberg (Antibarbarus, 1905) List of papers This thesis is based on the following papers, which are referred to in the text by their Roman numerals. I A. Sobkowiak, J. Ångström, T. K. Nielsen, Y. Cerenius, T. R. Jensen and M. Sahlberg. “Hydrogen absorption and desorption properties of a novel ScNiAl alloy” Applied Physics A 104 1 (2011) 235-238 DOI: 10.1007/s00339-010-6116-z II M. Sahlberg, J. Ångström, C. Zlotea, P. Beran, M. Latroche and C. P. Gómez. “Structure and hydrogen storage properties of the hexagonal Laves phase Sc(Al1−x Nix)2” Journal of Solid State Chemistry 196 (2012) 132-137 DOI: 10.1016/j.jssc.2012.06.002 III J. Ångström, R. Johansson, L. H. Rude, C. Gundlach, R. H. Scheicher, R. Ahuja, O. Eriksson, T. R. Jensen and M. Sahlberg. “Hydrogen storage properties of the pseudo binary Laves phase (Sc1−xZrx)(Co1−yNiy)2 system” International Journal of Hydrogen Energy 38 23 (2013) 9772-9778 DOI: 10.1016/j.ijhydene.2013.05.053 IV D. Korablov, J. Ångström, M. B. Ley, M. Sahlberg, F. Bessenbacher and T. R. Jensen. “Activation effects during release and uptake of MgH2” International Journal of Hydrogen Energy 39 18 (2014) 9888-9892 DOI: 10.1016/j.ijhydene.2014.02.112 V J. Ångström, C. Zlotea, M. Latroche and M. Sahlberg. “Hydrogen-sorption properties of Nb4M0:9Si1:1 (M=Co,Ni) hydrides” International Journal of Hydrogen Energy 40 6 (2015) 2692-2697 DOI: 10.1016/j.ijhydene.2014.12.031 VI J. Ångström, R. Johansson, O. Balmes, M. H. Sørby, R. H. Scheicher, U. Häussermann and M. Sahlberg. “Hydrogen absorption in rare-earth-gallide Zintl-phases LnGa (Ln=Nd, Gd)” manuscript Reprints were made with permission from the publishers. The author also contributed to the following published and/or accepted scholarly works which are not included in this thesis: i S. Kamali, N. Shahmiri, J. J. S. A. Garitaonandia, J. Ångström, M. Sahlberg, T. Ericsson and L. Hägerström. “Effect of mixing tool on mag- netic properties of hematite nanoparticles prepared by sol–gel method” Thin Solid Films 534 (2013) 260-264 DOI: 10.1016/j.tsf.2013.03.009 ii S. Frykstrand, C. Strietzel, J. Forsgren, J. Ångström, V. Potin and M. Strømme. “Synthesis, electron microscopy and X-ray characterization of oxymagnesite, MgO2·2MgCO3, formed from amorphous magnesium carbonate” CrystEngComm 16 (2014) 10837-10844 DOI: 10.1039/C4CE- 01641F iii V. Höglin, J. Ångström, M. S. Andersson, O. Balmes, P. Nordblad and M. Sahlberg, “Sample cell for in-field X-ray diffraction experiments” Results in Physics 5 (2015) 53-54 DOI: 10.1016/j.rinp.2015.01.006 iv J. Ångström, M. Sahlberg and R. Berger, “Real-time in-situ monitoring of the topotactic transformation of TlCu3Se2 into TlCu2Se2” Journal of Alloys and Compounds accepted (2015) DOI: 10.1016/j.jallcom.2015.02- .180 My contributions to the papers The authors contribution to the papers included in this thesis: I I made some of the syntheses, took part in the conception of the project and did the in-situ diffraction experiments together with the first author. I was involved in the writing and discussions about the manuscript. I approved the final proof of the paper. II I planned the work together with the main author and did most of the experimental work except the structural refinements and PCT measure- ments. I wrote parts of the manuscript and was involved in all of the discussions. I approved the final proof of the paper. III I planned and executed all the experimental work and the treatment and interpretation of the resulting data. The theoretical calculations were performed by the second author. I wrote most of the manuscript and was involved in all discussions. I approved the final proof of the paper. IV I executed most of the in-situ experiments, took part in the treatment in the data and wrote parts of the manuscript. I approved the final proof of the paper. V I planned all and executed most of the experimental work and the treat- ment and interpretation of the resulting data. I wrote most of the manu- script and approved the final proof of the paper. VI I planed and executed most of the experimental work. The theoretical calculations were performed by the second author. I did the majority of the treatment of the experimental data. I wrote most of the manuscript and approved the version appended to this thesis. Contents 1 Introduction ................................................................................................ 13 1.1 Examples of Metal Hydrides ......................................................... 13 1.1.1 Ionic Metal Hydrides ....................................................... 13 1.1.2 Metallic Metal Hydrides ................................................. 15 1.1.3 Covalent Metal Hydrides ................................................ 17 1.1.4 Zintl Phase Hydrides ....................................................... 17 1.2 Existing and Potential Applications of Metal Hydrides .............. 17 1.2.1 Ni–MH Batteries ............................................................. 17 1.2.2 Hydrogen storage ............................................................. 18 1.2.3 Thermal Storage .............................................................. 19 1.2.4 Other Applications and Effects of Hydrogen in Metals 20 2 Aims ........................................................................................................... 21 3 Methods ...................................................................................................... 23 3.1 Synthesis ......................................................................................... 23 3.1.1 Arc Melting ...................................................................... 23 3.1.2 Heat Treatment ................................................................ 23 3.1.3 Hydrogenation/Deuteration ............................................ 24 3.2 Diffraction ...................................................................................... 24 3.3 Characterisation by Diffraction Techniques ................................. 28 3.3.1 X-ray Single Crystal Diffraction .................................... 28 3.3.2 X-ray Powder Diffraction ............................................... 28 3.3.3 Neutron Powder Diffraction ............................................ 29 3.3.4 Determination of Lattice Parameters .............................. 30 3.3.5 Full Pattern Refinement Using the Rietveld Method .... 30 3.4 Thermodynamic and Kinetic Behaviour of