In order to help us understand more, please tell us about your sample preparation for each method - how thick is your thin layer? What is the substrate? What instrumental settings have you used? Best of all - show us your data (images or data files) so that we can see what the issue might be.

Dear Ian J Slipper, 

Thank you for your response, I have prepared the nanoparticles by a conventional solid route method and thin film was prepared by RF magnetron sputtering method on the Si substrate. I have taken the XRD for both samples by a XPERT PRO Diffractometer. I have attached the images of both samples. Kindly explain the reason. Thank you.

It seems you are punching through the thin film and getting most of the signal from the substrate at the higher angles. Try using grazing incidence diffraction for your thin film.

Thank you very much for your kind information. 

I think the nanoparticle sample seems to be a quite ideal powder sample having a nearly homogenous orientational distribution of the particles/crystallites. In the film I assume the crystallites show orientational effects, the sample is textured having a lot of microcrystallites which have the same orientation. Therefore some XRD peaks may be missing  compared to the nanoparticle System.   

Are you sure that the deposited phase is the same of bulk target? Are you sure that Si is a good choice as substrate? There is something known in the literature? In general with thin films an effect of preferred orientation induced by the structure of substrate is normal but in your pattern it does not seem so. Why the hkl  you superimpose on the pattern of thin film are different from those of bulk? 

Hi Manickam,

                        A powder sample of certain compound gets crystallizes in 3-D space lattice. Hence, it will give most reflections of all the planes. But in a thin film deposition process, the growth of crystal will be quite different. Sometimes, they will grow in 1-D or 2-D depending upon processing conditions. Hence due to this change in their crystal structure from powder, they show some of the reflections only. 

The peak at ~70 degrees is Si (004) which means you are using a Si (001) substrate. Did you remove the oxide layer usually present on Si before depositing your film? What was the deposition temperature? The shoulder peak identified as (233) is not from Si because structure factor rules don't allow it. (062) is also not from Si because a Si (001) substrate doesn't have a peak with that index at that angle. Is the target Bi2Fe4O9 or are you using reactive sputtering?  You could have deposited a completely different phase from that of your nano particles.