Materials for Renewable Energy  
Hydrogen and Hydrides
Structure and Dynamics
Stability and Kinetics
Electrochemistry
Theoretical Modelling
Instruments
Spectroscopy

Structure and dynamics

Knowing the structure and the hydrogen dynamics of complex hydrides on an atomic scale is the basis of understanding and controlling their functionality. Our main goals and methods are:

  • The Synthesis of various complex hydrides and deuterides (from the elements, mechanical, chemical reaction, isotope exchange)
  • Resolving the reaction paths and the corresponding crystallographic structures of the products (the desired complex hydrides) and the intermediate compounds.
  • Determination of the charge density distribution in the complex hydrides to understand the chemical stability of the hydrides
  • Determination of the collective hydrogen oscillation modes by means of inelastic neutron scattering
  • Determination of the hydrogen diffusion paths as the basis of hydrogen adsorption and desorption

 

The structure of complex hydrides is different from the structure of the consisting metallic elements. The hydrogen in the complex hydrides is often located in the corners of a tetraheder with boron or aluminum in the center. The negative charge of the anion [BH4]- and [AlH4]- is compensated by a cation e.g. Li+ or Na+.

The structure is analyzed by means of Rietveld-refinement of the neutron diffraction pattern. High quality X-ray diffraction data are measured at ESRF and SLS and the charge density distribution maps are computed by means of the minimum entropy method.

Inelastic and quasielastic neutron scattering techniques have been extensively used to study hydrogen dynamics in metal hydrides. We will apply these methods to complex hydrides to determine
collective motion, rotational motion and diffusion processes. The experimental results will be complimented and discussed on the basis of first principle model calculations.

The group is closely connected to the "stability and kinetics" group, which connects the fundamental structural characteristics to thermodynamic properties and the hydrogen adsorption/desorption kinetics.

 

New papers out:

homepage

www.empa.ch/H2E

 

contact:

Dr. Arndt Remhof, email: arndt.remhof@empa.ch

 

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