Electron beam induced changes in transition metal oxides.
Electron beam induced changes in maximal valence transition metal oxides V(2)O(5), M(o)O(3) and TiO(2) (anatase) were studied by means of electron energy-loss spectroscopy and electron diffraction in transmission electron microscopy. For V(2)O(5), the observed chemical shifts of the L-edge reveal the reduction of V(5+) to V(2+). The structure changes from orthorhombic V(2)O(5) to cubic VO. MoO(3) can be reduced to a phase with an oxidation state less than that in MoO(2). No notable structural or electronic change in TiO(2) (anatase) is observed. The different behaviours of the studied oxides under an electron beam are discussed with respect to bonding energy and lattice structure.
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Department of Inorganic Chemistry, Fritz Haber Institute of MPG, Faradayweg 4-6, 14195 Berlin, Germany. dangsheng@fhi-berlin.mpg.de