Hydrogen-deuterium exchange in bulk LiBH4.
Because of its apparent simplicity, diffusion of hydrogen in solids can be regarded as a general model system for diffusion. However, only rudimentary knowledge exists for the dynamics of hydrogen in complex hydrides. Insight into the specific diffusion process is given by hydrogen-deuterium exchange experiments. Thermogravimetry and Raman spectroscopy are used to measure the hydrogen-deuterium exchange during the decomposition of LiBH4. At a temperature of 523 K the self-diffusion constant of deuterium in LiBH4 is estimated to be D approximately 7 x 10(-14) m(2) s(-1). A careful analysis of the Raman spectra shows that hydrogen is statistically exchanged by deuterium in LiBH4; i.e., the diffusing species is assumed to be the single hydrogen atom.
Borgschulte
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EMPA, Swiss Federal Institute of Materials Research and Testing, Laboratory 138, Hydrogen & Energy, CH-8600 Dübendorf, Switzerland. andreas.borgschulte@empa.ch
Züttel
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Hug
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Racu
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Schoenes
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