Int. J. of Nanotechnology   »   2007 Vol.4, No.5

 

 

Title: The location of Ti atom in sodium alanate: an ab initio spin-polarised study

 

Author: A.J. Du, Sean C. Smith, G.Q. Lu

 

Addresses:
Centre for Computational Molecular Science and ARC Centre for Functional Nanomaterial, The University of Queensland, AIBN Building 75, OLD 4072, Brisbane, Australia.
Centre for Computational Molecular Science and ARC Centre for Functional Nanomaterial, The University of Queensland, AIBN Building 75, OLD 4072, Brisbane, Australia.
Centre for Computational Molecular Science and ARC Centre for Functional Nanomaterial, The University of Queensland, AIBN Building 75, OLD 4072, Brisbane, Australia

 

Abstract: In this work, ab initio spin-polarised Density Functional Theory (DFT) calculations are performed to study the interaction of a Ti atom with a NaAlH4(001) surface. We confirm that an interstitially located Ti atom in the NaAlH4 subsurface is the most energetically favoured configuration as recently reported (Chem. Comm. (17) 2006, 1822). On the NaAlH4(001) surface, the Ti atom is most stable when adsorbed between two sodium atoms with an AlH4 unit beneath. A Ti atom on top of an Al atom is also found to be an important structure at low temperatures. The diffusion of Ti from the Al-top site to the Na-bridging site has a low activation barrier of 0.20 eV and may be activated at the experimental temperatures (∼323 K). The diffusion of a Ti atom into the energetically favoured subsurface interstitial site occurs via the Na-bridging surface site and is essentially barrierless.

 

Keywords: density functional theory; ab initio DFT calculation; spin polarisation; surface adsorption; diffusion; activation barrier; Ti atoms; titanium atoms; sodium alanate; nanotechnology; hydrogen storage systems.

 

DOI: 10.1504/IJNT.2007.014751

 

Int. J. of Nanotechnology, 2007 Vol.4, No.5, pp.564 - 573

 

Available online: 06 Aug 2007

 

 

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