APPLICATION OF A NEW METHOD FOR ABSORPTION CORRECTION IN HIGH-ACCURACY, QUANTITATIVE EDX MICROANALYSIS IN THE TEM - ANALYSIS OF OXYGEN IN CUO-BASED HIGH-TC SUPERCONDUCTORS

A new method for the absorption correction of EDX analysis in the TEM including low-energy X-ray lines was applied. The Cu/O mole fraction r atio for YBa2Cu3O7-x ceramics was determined quantitatively using CuO as standard. Preliminary experiments were carried out to investigate t he absorption behaviour (as a function of specimen thickness) of the l ow-energy X-ray lines (O-K and Cu-L) in CuO, YBa2Cu3O7-x and (Bi, Pb)2 Sr2Ca2Cu3O10+delta. These experiments confirmed the general estimation that fluorescence effects are negligible for the transition metal/O m ole fraction determination of transition metal oxides by EDX in the TE M. By a combination of EDX and EELS measurements and a thickness deter mination applying the trace method on (001) twin boundaries in CuO, th e Cu mass absorption coefficient for the O-K line could be refined. Th e tabulated value was found to be too large by a factor of 2. The stre ngth of the applied method (with respect to the usually applied k-fact or analysis) is that transmission coefficients are determined experime ntally. Thus, the thickness of the specimen areas, at which spectra ar e acquired, as well as the mass absorption coefficients need not be kn own for quantitative EDX analysis.