The elemental composition of the OCMs was studied by EDX
analyses which proved that the desired composite structure,
encapsulating iron oxide in an LSF731 matrix, was obtained using
both preparation methods. Areas with a higher concentration of
iron oxide were found in the particles when either sub-micron iron
oxide powders or 20–40 lm iron oxide powders were used during
the preparation. As an example, Fig. 3 shows a SEM and EDX of the
LSF-30Fe-MM-20-40 OCM. Iron oxide is in the form of layers, typical
of the structure of haematite, while LSF731 is in the form of
small granules. Grain boundaries can be distinguished. Fig. 3b
shows the EDX analysis of the same OCM which confirms the presence
of iron oxide in specific areas of the particle surrounded by
the LSF731.