Dear Siddig Abuelgasim

First, if the copper oxide does not react with the inert support, you will have two distinct diffraction patterns - one for the oxide and one for the support.

Second, you would have better accuracy if you used all diffraction peaks in the XRD pattern for copper oxide. Remember that the height, width and position of these peaks determine many aspects of the material's structure. You can use to analyze the XRD pattern some fitting program or a refinement method like the Rietveld method, for example.

Best regards, Carlos

Dear Siddig Abuelgasim,

I agree with Carlos Ariel Samudio Pérez and Steven Van Petegem,

I think that the attached article may help you because it contains a solid containing two phases (two different materials in d-space and lattice parameters) from XRD data.

Article Properties of (NiO)1-x(ZnO)x thin films deposited by spray pyrolysis

Best wishes

Thank you all, I really appreciated your help. The support did not react with copper oxide. Are you think this is also right for calculating crystallite size?

The crystallite size is inversely proportional to the line width of the XRD peak.

The Rietveld method allows you to calculate the particle size. But you will have to be careful with the necessary parameters.

Best

Thank you dear Carlos Ariel Samudio Pérez for your care and nice response