Summary. --Kinematic equations describing velocity and acceleration of a ball in a vial of a planetary ball-mill have been derived. The consequent energy transfer from the mill to the system constituted by the powder, the balls and the vials have been evaluated by theoretical-empirical approach. Mixtures of elemental iron and zirconium powders corresponding to the average Fe2Zr composition have been mechanically alloyed in different milling conditions. The end products strongly depend on the operative milling conditions and a clear correlation between them and the input energy has been found. PACS 81.20 -Specialized material fabrications and fabrication techniques.

No abstract

No abstract

No abstract

Novel chemistries for secondary batteries are investigated worldwide in order to boost the development of next-generation rechargeable storage systems and especially of lithium-devices. High capacity anode materials for Li-ion cells are at the center stage of R&D in order to improve the performances. In this view, conversion materials are an exciting playground. Among the various proposed class of conversion anodes, metal hydrides are probably the most challenging and promising due to the high theoretical capacities, instability toward the standard carbonate-based electrolytes, large volume variations upon cycling, and moderately low working voltages. Among them lightweight hydrides, like alkaline alanates, are an almost unexplored family of materials. In this study, we present a fundamental study on the electrochemical conversion reaction of sodium alanates: NaAlH4, Na3AlH6, and Na2LiAlH6. Our goal is to improve the understanding of the basic solid-state electrochemistry that drives the conversion reactions of these materials in lithium cells. Samples have been prepared mechanochemically and characterized by X-ray diffraction (XRD), infrared spectroscopy, and transmission electron microscopy. All materials have been assembled in lithium cells with a commercial liquid electrolyte to test their electrochemical activity. The Li incorporation/deincorporation mechanism for all materials has been explored by in situ XRD and interpreted also in view of density functional theory thermodynamic calculations.