High pressure synthesis of novel metal hydrides

Abstract

Among metal hydrides, magnesium hydride (MgH2) would be a promising candidate for hydrogen storage materials because of its high hydrogen-storage capacity 7.6 mass%. However, the dehydrogenation temperature is too high for wide practical applications. Novel magnesium-based hydrides with better dehydrogenation properties than MgH2 can be prepared under hydrogen pressure of gigapascal (GPa). For instance, Mg7TiH 16 6.9 mass% would release hydrogen at a lower temperature by 130 K than MgH2. The Mg-H ionic bonding distance in Mg7TiH 16 is longer than that in MgH2. The observed lower dehydrogenation temperature seems to be consistent with the structure.