XRD will not provide you a definite answer about doping. But it can provide some useful clue. The best one is by observing if there is some shift in the 2 theta position peaks in relation to the undoped samples. But make sure that it either can be useful or not, since this shift will be very slight (if it happens).

The cause of this slight shift is due to change on unit cell parameter due to possible incorporation of the doping species in the unit cell of the "host" material. In case that Ag was converted to silver oxide, probably you would see additional peaks, indicating that a new silver oxide crystalline phase was formed. Again, it might not be conclusive, since the amount of oxide formed maybe below XRD detection limit.

In view of all those XRD limitations, I recommend you to use some other techniques: Raman Spectroscopy (will indicate raman mode shifts, generally, the shifts are more evident than in XRD), and elemental analysis through SEM-EDS or TEM-EDS.

In which form is it (powder or thin film) ??

From XRD data you can come conclusion about doping with the help of Vegard's law

as well as ICDD-PDF2 database. If its powder you can use Rietveld refinement procedure.

But be cautious that don't come to final conclusion merely with XRD method, you have to try other complimentary methods such Raman Spectroscopy, SEM-EDX,  EBSD, etc.,

If your metal enters as a doping in the host structure the xrd pattern does not change (only lattice parameters), you can see peak shifts, it depends from the doping level and the difference of ionic radii. So it could be difficult to decide if the doping was effective only from xrd. Different is the case in which the dopant segregate as oxide or metal (you should see their peaks).

thanks everybody

You have to consider if the dopant addition causes a change in the lattice parameters. If the dopant is fully substituted in the lattice structure lattice parameters are influenced. If dopant forms a solid solution at grain boundary or it is in an amorphous phase you can see only a small peak shift. I suggest you a SEM-EDX with a mapping. 

"XRD data e.g. silver is doped in ZnO or TiO2"

Below is an example real time 2D diffractogram, using a modern 2D spatially resolved 25mm diameter detector (Pixel size 76um), of a composite sample containing:

• Amorphous binder.
• Crystalline powders.
• Crystalline foil with preferred orientation.

https://www.flickr.com/photos/85210325@N04/7988760159/in/album-72157632728981912/

thanks ravi ananth sir and everybody who involved in this question

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Please see following link:

https://youtu.be/2OTuQvknNg0