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MM: Fachverband Metall- und Materialphysik
MM 31: Topical Session: Hydrogen in Materials: from Storage to Embrittlement V
MM 31.3: Vortrag
Mittwoch, 20. März 2024, 11:00–11:15, C 130
Mixed Metal Solid Solutions in Amide-Hydride Systems — •Thi Thu Le1, Michele Chierotti2, Stefan Walders3, Denis Kramer3, Alexander Schoekel4, Thomas Klassen1,3, and Claudio Pistidda1 — 1Helmholtz-Zentrum hereon GmbH, Geesthacht, Germany — 2University of Torino, Torino, Italy — 3Helmut Schmidt University, Hamburg, Germany — 4Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
Metal amide-hydride materials have been extensively studied for use in energy applications. In particular, the solid solution formation in metal-amide hydride system promotes fast hydrogen sorption kinetics and tunes the thermodynamics, which allow hydrogen absorption/desorption below 150 *C in hydrogen storage systems. In addition, these intermediates are potentially ionic conductors for solid-state batteries. In this work, a series of M-N-H solid solution structures based on mixed MNH2-MH materials of Group 1 elements (M = K, Rb, Cs and their combinations) is reported. The results obtained by ex-situ / in-situ XRD, and MAS NMR confirm the formation of mixed solid solution associated with an exchange between both anionic (NH2- and H-) and cationic species (K+, Rb+ and Cs+). Moreover, MD calculations show that the NH2 rotation barrier is lowest in the Cs system, which has the lowest phase transition temperature, indicating a positive correlation of two variables, where a higher anion rotation barrier is associated with a higher phase transition temperature, in agreement with experimetal data. This work provides the basis for further studies on the ionic conductivity of solid electrolytes or dopants.
Keywords: mixed metal amide-hydride; ion mixing; solid solution; anion rotation; proton rotation