Dresden 2009 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 49: Hydrogen in Metals

MM 49.6: Talk

Friday, March 27, 2009, 11:30–11:45, IFW D

Study of complex hydrides prepared by mechano-chemical synthesis — •Carine Rongeat, Christian Geipel, and Oliver Gutfleisch — IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden, Germany

Ball milling has been widely used for the synthesis of metal hydrides, e.g. MgH2, with high sorption performances. However, metal hydrides cannot address the requirements imposed for solid state hydrogen storage in mobile application. A new class of hydrides, the complex hydrides are attracting much interest due to their high capacity and predicted moderate temperature of operation. High-pressure reactive milling with in-situ monitoring the pressure and temperature was applied to the synthesis of NaAlH4 doped with different additives. Useful information on the kinetic properties of the compound could be derived from this system already during synthesis. The same system was applied for the synthesis of Ca(BH4)2 but different results were obtained due to the higher stability of the boride compounds used. Finally, another route for the synthesis of complex hydride is to performed the metathesis reaction during milling, e.g. the synthesis of Mg(BH4)2 can be obtained (with LiCl) by the reaction between LiBH4 and MgCl2. All the compounds synthesized by mechano-chemical synthesis are analyzed by means of advanced structural characterization techniques (Raman spectroscopy, XPS, in-situ XRD). Their hydrogen sorption properties were also studied by various methods (DSC, TGA).