Formation of CaB6 in the thermal decomposition of the hydrogen storage material Ca(BH4)2
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Updated: Mar 18, 2026

Supercritical Nitrogen Processing for the Purification of Reactive Porous Materials
Published on: May 15, 2015
Christoph J Sahle1, Christian Sternemann2, Carlotta Giacobbe1
1European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France. christoph.sahle@esrf.fr.
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.
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