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Compound Formation in Ti-Doped Sodium Aluminum Hydrides

Published online by Cambridge University Press:  26 February 2011

E.H. Majzoub ,
R. Stumpf ,
S. Spangler ,
J. Herberg  and
R. Maxwell
E.H. Majzoub*
Affiliation:
Sandia National Laboratories, P.O. Box 969, Livermore, CA, 94551, USA
R. Stumpf
Affiliation:
Sandia National Laboratories, P.O. Box 969, Livermore, CA, 94551, USA
S. Spangler
Affiliation:
Sandia National Laboratories, P.O. Box 969, Livermore, CA, 94551, USA
J. Herberg
Affiliation:
Lawrence Livermore National Laboratories, P.O. Box 969, Livermore, CA, 94551, USA
R. Maxwell
Affiliation:
Lawrence Livermore National Laboratories, P.O. Box 969, Livermore, CA, 94551, USA
*
1 Tel.: +1-925-294-2498; fax: +1-925-294-3410. E-mail address: [email protected]
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Abstract

Renewed interest in hydrogen storage materials has resulted in the development of Ti-doped NaAlH4. Different doping methods such as mechanical milling with powdered TiCl3, or wet doping in solvents such as tetrahydrofuran (THF), yield enhanced kinetics. Still, the location and action of the Ti dopant is an open question. In order to address titanium substitution in the bulk, we present lattice parameter measurements of crushed single crystals which were exposed to Ti during growth. Rietveld refinements suggest that the titanium does not appear to enter the bulk by this method of exposure. Therefore, reaction products are investigated by x-ray diffraction of completely reacted samples of solvent-mixed versus mechanically milled 3 NaAlH4+TiCl3. Formation of TiAl3 is observed in mechanically milled materials, but not solution mixed samples, where bonding to THF likely stabilizes Ti-based nano-clusters. The Ti in these clusters is activated by mechanical milling.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 801: Symposium BB – Materials and Technologies for a Hydrogen Economy , 2003 , BB4.2
Copyright
Copyright © Materials Research Society 2004

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