Dear Vikas,

Please provide more information such as what are the crystal material and substrate, how did you perform the XRD? Do you have the XRD results? 

"epitaxial relation between two crystals" - Please clarify.

"Phi and 2Theta scans for both the crystals at the same time" - What does this mean? Remember Phi, Chi, Omega, and 2Theta are dimensions in reciprocal space.

"Epitaxy refers to the deposition of a crystalline overlayer on a crystalline substrate."

No two crystals (real space) may occupy the same volume in reciprocal space. If they do, then they are of the same "coherently diffracting domain" (CDD). Right?

Especially, in the parallel beam geometry which I assume is what you are utilizing, correct?

https://en.wikipedia.org/wiki/Epitaxy

Whether you asking about the epitaxial relationship between substrate and film planes ? or

the epitaxial relationship between the different planes within the single crystal?

otherwise .....I think .....your question "If you have Phi and 2Theta scans for both the crystals at the same time." has no meaning.

How could you measure the Phi and 2Theta scans for different crystals at the same time ????

The same thing has been pointed out by Ravi.

Sorry, let me clear.

Thanks for your concern

I mean the epitaxial relationship between substrate and film.

I scanned 2theta fixed Phi and fixed 2 theta scanned Phi.

Now I have 2 theta and Phi scan for both thin film and substrate and want to establish epitaxial relationship between substrate and thin film

First, without seeing the PHI scans it's difficult to give the answer.

Please give information abt the substrate and film. 

Epitaxial relationship between substrate and film planes can be made by comparing   both the data. But knowledge of crystallography is required.

Thanks

Dear Dr. Savan,

Thank you

, Please see the attached file

Dear Yuen-Yee Wong, please check the attached data