You can confirm by doing XRD of your sample. In XRD pattern, the peaks of every phase will come. Using these peaks you can also quantify the ratio of these phases.

First, you have to be sure as Dr. Singh said. 

But there are several phases for Fe2O3 for instance. According to the crystal structure it belongs to, you may obtain different peaks. You have to analyse XRD and make a profile fit.

Exactly as stated by Ram and Murat. You cannot get direct structural information from spectroscopy methods (and usually the elemental/vibrational information you get is only from the surface and not a bulk probe). Powder x-ray diffraction will tell you what structural phases are in your material as well as their percentages and a number of other information that you may or may not be interested in depending on the degree of analysis you want to pursue.

thanks Dr  Singh, Dr Murat , and Dr  Margulies.

sometimes, XRD is not appropriate method if the percentage of calcium is very small.

i prepared this composite and no peaks related to calcium or its oxide in XRD analysis. Analyzing the sample using XPS confirm the presence of calcium, but the  peak positions shifted about the reported data od calcium oxide or calcium ferrite.

Is there another method to elucidate the chemical state of the composition?

EDS