“Dynamics of porous and amorphous magnesium borohydride to understand solid state Mg-ion conductors”
A comprehensive study combining x-ray total scattering and quasi elastic neutron scattering (QENS) to help unravelling the complex interplay of the structure-property-relationship in crystalline and amorphous Mg-ion conductor Mg(BH4)2. In this study, published in June 2020 in scientific reports – nature research, electrochemical impedance spectroscopy of crystalline and amorphous Mg(BH4)2 confirmed that the conductivity of the latter is ~2 orders of magnitude higher at 353 K. The challenge in understanding the root cause of the observed high conductivity, is the difficulty to determine the structure of amorphous glasses in general. Since glasses are x-ray amorphous, synchrotron total scattering was performed to calculate the corresponding pair distribution functions (PDF). PDF analyses indicate a higher amount of disorder regarding the [BH4]- tetrahedra as well as the preservation of a now highly disordered 3D net of interpenetrating channels. Additionally, QENS was employed to study the rotational mobility of the [BH4] units, proofing a much larger fraction of activated [BH4] rotations in amorphous Mg(BH4)2.