It's quite indeed strange ! Could you add a picture of your pattern ? 

Difficult to answer unless u profide more information. Did u take have a naked subtrate pattern?

It's difficult to give an unique answer. One of the reason - substrate is textured, therefore not all peaks will be present in the diffraction pattern (compared to powder sample, of course). The second reason - penetration depth of X-rays is different in 2Theta angular range of diffraction pattern (it increases with increasing the 2Theta angle). So, at low 2Theta angles substrate peaks "disappear", if the film thickness has certain value. Show your diffraction pattern and give some info about thing film thickness and X-ray radiation.

Dear Sagarika Nayak

Can you attach the XRD pattern? to could reply you. What about your sample, their thickness and the range of two-theta.

Thanks

Hello, generally the xrd peaks of the substrate may be gone missing when your thin film becomes thicker. So the annealing process may have caused the film dilatation which avoid the electron beam to reach the solid support. Good luck

Hi Sagarika,

You do not have to share your RAW DATA of any measurement to anyone. Please send the Picture file/snapshot of the XRD data plot and also mention the film thickness. XRD peak of substrate vanishes only if the film thickness is too highand/or the substrate itself is highly amorphous in nature. 

Please follow Laurène Youssef's and Igor Kolodiy's comments also.

Good luck.

If the Fe2TeO6 film is quite thick then the film cover whole Al2O3 substrate. X-ray only penetrate of micron. That is why you cannot find the peak of AlO3. How about the peak of  Fe2TeO5. If your sample is pure crystal phase and very homogeneous you can get whole peaks.  I wonder the film is not 100% crystal. May be there is around 50% amorph and the film sample is not perfect same thickness covering substrate. You can check it by AFM to make sure our assumption. 

I agree with the answer that one can not get Substrate peak if the film is thick enough as x-rays could not penetrate the film.

But the before accepting this answer, I would suggest that.....

1.Check your film thickness either using thickness profilometer or the best way is to go for spectroscopic ellipsometry. (X-ray reflectometry can not be used for measuring thickness above ~150-200 nm)

2. Sometimes misorientation/misalignment of the substrate can not give the proper peaks what we expect.

Hello All,

Please note that (in this page) Dr. Ahmed tried to help Sagarika. But it is very unfortunate that someone devoted his response without any reason. There is nothing wrong in his response. Please try to justify before devoting any response.