Influence of crystal orientation on oxygen analysis in NiO with energy dispersive X-ray analysis

Characteristic X-ray spectra of stoichiometric NiO were investigated by EDX . Peak intensities of Ni-K alpha and O-K alpha are determined for several z one axes and also off-axis specimen orientations. The intensity ratios depe nd strongly on specimen orientation, resulting in errors of up to 30% in co ncentration analysis. Based on Bloch wave calculations, the dependence on t he zone axis is explained qualitatively by the ordered structure of NiO, as suming the atoms to be ideal point scatterers. However, in order to get a q uantitative description this simple model is not sufficient: the spatial st ructure of the electron shells must also be considered.