Evidence for the existence of β-Na3AlH6: Monitoring the phase transformation from α-Na3AlH6 by in situ methods

The phase transformation of α-Na3AlH6 to β-Na3AlH6 was characterized by in situ DSC and high-temperature X-ray diffraction methods. The detection of the phase transformation from the α- to the β-polymorph requires rapid heating rates and a very fast data acquisition. The influence of the preparation method on the stability of both polymorphic forms most probably originates from different particle sizes of the parent samples.