Reactivity of hydrides by in-situ diffraction
Y. Filinchuk, I. Dovgaliuk, V. Ban, N. Tumanov, F. Morelle
IMCN, Université Catholique de Louvain, pl. L. Pasteur 1, 1348 Louvain-la-Neuve, Belgium
In this talk I shall present problems that can be tackled by diffraction experiments under gas
pressures. The nature of solid-gas interaction defines what information is assessable:
 For large-pore systems, macroscopic information can be obtained, such as on occurrence
of phase transitions, variation of cell parameters, size of hysteresis loops. These data are
very useful in combination with other techniques, phenomenological models and
theoretical calculations.
 For the small-pore systems, in-situ diffraction data allow to access microscopic
information, such as location of guest molecules, nature of host-guest interactions and
sometimes even energy differences for adsorption sites.
 When a strong chemical interaction occurs between the crystalline material and the gas,
complex sequences of chemical reactions can be disentangled from diffraction data alone.
De- and re-hydrogenation reactions of complex (chemical) hydrides are the examples.
Typical experimental setups and pressure cells will be presented, as well as our new
methodological developments [1] aiming for extracting isosteric heats of adsorption vs
loading from diffraction data.
Besides the methodological part, I shall focus on solid-state transformations in complex
hydrides, induced by variation of temperature and hydrogen pressure. In-situ powder
diffraction is our most valuable tool to find new hydrides, understand their reactivity,
decomposition pathways, hydrogen release and uptake [2, 3]. Decomposition pathways can be
tuned by reaction conditions. All this information inspires us to try different ways to
synthesize new hydrides and their decomposition intermediates, for example by using a ball
mill, gas atmospheres, ultra-high vacuum etc. At present, the random search for better
hydrogen storage systems starts to give the way to the rational design.
References
[1] Y. Filinchuk, B. Richter, T.R., Jensen V. Dmitriev, D. Chenryshov, H. Hagemann,
Angew. Chem. Int. Ed., 50 (2011) 11162-11166.
[2] D.B. Ravnsbæk, L.H. Sørensen, Y. Filinchuk, F. Besenbacher, T.R. Jensen, Angew. Chem.
Int. Ed., 51 (2012) 3582-3586.
[3] R. Černý, Y. Filinchuk, Z. Kristallogr., 226 (2011) 882-891.