Valence state mapping of cobalt and manganese using near-edge fine structures

The properties of transition metal oxides are related to the presence Of elements with mixed valences. The spectroscopy analysis of the valence,states is feasible experimentally, but a spatial mapping of valence states of transition metal elements is a challenge to existing microscopy techniques. In this paper. with the use of valence state information; provided by the white lines and near-edge fine structures observed using the electron energy-loss spectroscopy (EELS) in a transmission electron microscope (TEM), a novel experimental approach is demonstrated to map the valence state distributions of Mn and Co using the ratio of white lines in the energy-filtered TEM. The valence state map is almost independent of specimen thickness in the thickness range adequate for quantitative EELS microanalysis. An optimum spatial resolution of similar to 2 nm has been achieved for a two-phase Co oxides. (C) 2000 Elsevier Science Ltd. All rights reserved.