Analytical Tem Characterisation of Catalytic Materials

The application of analytical transmission electron microscopy in characterisations of catalytic materials is presented by studying the mechanically activated vanadium pentoxide V2O5. Local morphology and lattice distortion are studied by TEM while the oxidation states are determined by EELS. The mechanical activation can be described as a two -stage process: crushing of large crystals into small ones (macroscopic process) followed by amorphisation and reagglomeration of the fragments (microscopic process). No mill ing equilibrium state can be found. Energy-loss spectra reveal the reduction of vanadium via oxygen loss. The formation and distribution of V 4+ or V species depends on the history of milling.