An x-ray photoemission electron microscopy study of the formation of Ti-Al phases in 4 mol% TiCl3 catalyzed NaAlH4 during high energy ball milling

Nanotechnology. 2009 May 20;20(20):204014. doi: 10.1088/0957-4484/20/20/204014. Epub 2009 Apr 23.

Abstract

This study reports reaction pathways to form TiAlx metallic complexes during the high energy ball milling of 4 mol% TiCl3 with NaAlH4 powders determined using local structure analysis of Tix+ and Alx+ species. Using x-ray photoemission electron microscopy (XPEEM) and x-ray diffraction (XRD), the oxidation state of Alx+ and Tix+ and the crystalline compounds existing in equilibrium with NaAlH4 were tracked for samples milled for times of 0 (i.e. mixing), 5, and 25 min. XPEEM analysis of the Al K edge after 5 min of milling reveals that Al remains in the 3+ oxidation state (i.e. in NaAlH4) around Ti0-rich regions of the sample. After 25 min of high energy milling, Ti0 has reacted with Al3+ (in nearby NaAlH4) to form TiAlx complexes. This study reports the pathway for TiAlx complex formation during milling of 4 mol% TiCl3catalyzed NaAlH4 to be as follows: (1) Ti3+ reduces to Ti0 (with Al3+ near Ti0 regions) and (2) Ti0 reacts with Al3+ in NaAlH4 to form TiAlx complexes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alloys / chemistry*
  • Aluminum Compounds / chemistry*
  • Crystallization / methods*
  • Macromolecular Substances / chemistry
  • Materials Testing
  • Microscopy, Electron / methods*
  • Molecular Conformation
  • Nanostructures / chemistry*
  • Nanostructures / ultrastructure*
  • Nanotechnology / methods*
  • Particle Size
  • Phase Transition
  • Sodium Compounds / chemistry*
  • Surface Properties

Substances

  • Alloys
  • Aluminum Compounds
  • Macromolecular Substances
  • Sodium Compounds
  • sodium aluminum hydride
  • titanium aluminum alloy