On the state of the titanium and zirconium in Ti- or Zr-doped NaAlH₄hydrogen storage material

Abstract

The state of the titanium and zirconium in metal doped NaAlH4 was studied by X-ray diffraction analysis and quantitative Rietveld refinements. For the Ti-doped system, Ti is present in a highly dispersed, X-ray amorphous phase together with metallic aluminium. After the extraction of NaAlH4, an Al–Ti alloy forms upon heating of the solid. For the Zr-doped system, an Al–Zr alloy forms already during the doping procedure and remains during the de- and rehydrogenation cycles.