title: Formation of CaB6 in the thermal decomposition of the hydrogen storage material Ca(BH4)2.
abstract: Using a combination of high resolution X-ray powder diffraction and X-ray Raman scattering spectroscopy at the B K- and Ca L2,3-edges, we analyzed the reaction products of Ca(BH4)2 after annealing at 350 °C and 400 °C under vacuum conditions. We observed the formation of nanocrystalline/amorphous CaB6 mainly and found only small contributions from amorphous B for annealing times larger than 2 h. For short annealing times of 0.5 h at 400 °C we observed neither CaB12H12 nor CaB6. The results indicate a reaction pathway in which Ca(BH4)2 decomposes to B and CaH2 and finally reacts to form CaB6. These findings confirm the potential of using Ca(BH4)2 as a hydrogen storage medium and imply the desired cycling capabilities for achieving high-density hydrogen storage materials.
authors.affiliation: European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France. christoph.sahle@esrf.fr.
authors.forename: Christoph J
authors.initials: CJ
authors.lastname: Sahle
authors.affiliation: Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany. christian.sternemann@tu-dortmund.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Sternemann
authors.affiliation: European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France. christoph.sahle@esrf.fr.
authors.forename: Carlotta
authors.initials: C
authors.lastname: Giacobbe
authors.affiliation: Materials for Energy Conversion, Empa, Ch-8600 Dübendorf, Switzerland.
authors.forename: Yigang
authors.initials: Y
authors.lastname: Yan
authors.affiliation: Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany. christian.sternemann@tu-dortmund.de.
authors.forename: Christopher
authors.initials: C
authors.lastname: Weis
authors.affiliation: Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany. christian.sternemann@tu-dortmund.de and Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Harder
authors.affiliation: Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany. christian.sternemann@tu-dortmund.de.
authors.forename: Yury
authors.initials: Y
authors.lastname: Forov
authors.affiliation: Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany and Deutsches GeoForschungsZentrum, Section 3.3, Potsdam, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Spiekermann
authors.affiliation: Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany. christian.sternemann@tu-dortmund.de.
authors.forename: Metin
authors.initials: M
authors.lastname: Tolan
authors.affiliation: European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France. christoph.sahle@esrf.fr.
authors.forename: Michael
authors.initials: M
authors.lastname: Krisch
authors.affiliation: Materials for Energy Conversion, Empa, Ch-8600 Dübendorf, Switzerland and Crystallography, Institute for Geo- and Environmental Science, Albert-Ludwigs-University Freiburg, D-79098 Freiburg im Breisgau, Germany.
authors.forename: Arndt
authors.initials: A
authors.lastname: Remhof