Valence state coordination and incorporation of Ti and Cr into lower mantle phases : new insight from electron energy loss spectroscopy The knowledge of Ti4+ Ti3+ and Cr3+ Cr2+ ratios is particularly important for understanding the incorporation element partitioning and oxidation state in the Earths mantle and other rocky solar system bodies. In addition both d elements participate in a number of redox reactions taking place on the Earths surface and in the Earths crust. Also the redox reactions are of great importance for the chemistry of materials material and environmental sciences. Thus in the presented study calibration techniques for the determination Ti and Cr oxidation state using electron energy loss spectroscopy (EELS) are developed. In order to explain the signals of Ti and Cr electron energy loss spectra L3 2 electron energy loss near edge structures (ELNES) of a number of Ti and Cr bearing standard materials have been measured in a transmission electron microscope. The Ti and Cr containing standards represent a set of materials with either pure (Ti2+ Ti3+ Ti4+ Cr2+ Cr3+ Cr4+ Cr5+ Cr6+) or mixed (Ti3+:Ti4+ in various ratios) valence states known coordination (octahedral and tetrahdedral) and site symmetry. It was found that octahedrally coordinated titanium is very sensitive to the polyhedral distortions. Effects of polyhedral distortions are particularly observed for rutile and anatase (both TiO2) and two oxides with mixed Ti3+ Ti4+ valence state i.e. the Magnéli phases Ti4O7 and Ti5O9. The effect of valence state manifests itself in a systematic chemical shift of Ti and Cr white lines by 1.5 2.0 eV per valence state. On the basis of collected Ti L3 2 and Cr L3 2 ELNES spectra are developed two new quantification techniques for the determination of Ti4+ Ti3+ and Crn+ SCr ratios. One particular application of the EELS technique in mineralogy is the analysis of the local atomic environments in minerals. The geochemical properties of titanium and chromium in the Earths lower mantle are still not well constrained. ...