Influence of the ball milling conditions on the preparation of rare earth aluminum hydrides

The ball milling conditions in the preparation of rare earth aluminum hydrides from NaAlH4 and rare earth chlorides have a significant influence on product formation. Defined milling times and appropriate rotational speeds are required to obtain the desired products. It has been shown that starting directly from Na3AlH6 does not lead to the formation of REAlH6. Starting from rare earth iodides instead of chlorides allows dissolution of the alkali metal iodide formed and, therewith, the preparation of salt-free rare earth aluminum hydrides

Crystal structure of bis(diglyme-O,O′,O″)bis((μ₂-deutero)- trideuteroaluminato-D)calcium, Ca(AlD₄)₂(C₆H₁₄O₃)₂

C12H28Al2CaD8O6, monoclinic, P121/c1 (no. 14), a = 9.9889(2) Å, b = 15.7816(3) Å, c = 14.0935(2) Å, β = 92.758(1)°, V = 2219.1 Å3, Z = 4, Rgt(F) = 0.025, wRref(F2) = 0.071, T = 100 K

Synthesis, Crystal Structures, and Hydrogen-Storage Properties of Eu(AlH₄)(₂) and Sr(AlH₄)(₂) and of Their Decomposition Intermediates, EuAlH₅ and SrAlH₅

Complex Eu(AlH4)(2) and SrAlH4(2) hydrides have been prepared by a mechanochemical metathesis reaction from NaAlH4 and europium or strontium chlorides. The crystal structures were solved from powder X-ray diffraction data in combination with solid-state 27Al NMR spectroscopy. The thermolysis pathway was analyzed in detail, allowing identification of new intermediate EuAlH5/SrAlH5 compounds. Rehydrogenation experiments indicate that the second decomposition step is reversible

Direct synthesis of pure complex aluminium hydrides by cryomilling

Simple mechanochemical procedures can be used for the solid-state preparation of stable complex aluminium hydrides as hydrogen storage materials. For the synthesis of unstable complex hydrides, cryomilling at temperatures at which product decomposition does not take place under milling conditions appears to be a viable method. To probe the potential of cryomilling for the synthesis of complex aluminium hydrides, the reactions of different alkaline hydrides with AlH3 were tested under these conditions

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