Comparative studies of the decomposition of alanates followed by in situ XRD and DSC methods

The decomposition of various alkali and alkaline earth complex alanates and the formation of intermediate compounds was studied by in situ X-ray high-temperature diffraction and differential scanning calorimetry (DSC) experiments. Differences of the reaction pathways during thermolysis for the alkali and the alkaline earth aluminum hydrides were determined. During the thermolysis of Mg(AlH4)2 and Ca(AlH4)2, the appearance of metal hydrides in combination with alloys was observed, whereas for the alkali alanates LiAlH4 and KAlH4, intermediate aluminum hydrides but no alloys are formed. For the alkali salt-containing KAlH4 systems a strong influence due to the presence of salts on the decomposition temperatures are observed. In addition, the decomposition temperatures are also significantly influenced by the type of salt present. For the first time, the decomposition of the LiMg(AlH4)3 and Na2LiAlH6 systems was studied by in situ methods.