Synthesis and Properties of Magnesium Boranate

M. Fichtner, Ch. Chlopek, Ch. Frommen, A. Léon

¹ Karlsruhe Research Center, Institute for Nanotechnology, P.O.Box 3640, D-76021 Karlsruhe, Germany;

Boranates, either in pure form or combined with a binary metal hydride in a reactive composite, are interesting materials for hydrogen storage because of their high gravimetric hydrogen content. Whereas Li and Na boranate exhibit a high stability so that high desorption temperatures are necessary to desorb the hydrogen, magnesium boranate is less stable and might therefore be interesting for applications at moderate working temperatures.

Several ways to synthesize Mg(BH₄)₂ were tried, by chemical routes and by reactive milling of MgB₂ under hydrogen pressures around 100 bar. The structures of the intermediates and products were investigated by infrared spectroscopy and powder X ray diffractometry. Thermal properties were determined in TGA-MS and high pressure-DSC measurements.