Are you doing Grazing incidence diffraction?  Then the effect of stresses (which can be huge in CrN) have different effects on 111 and 222

I think  it is hard to say unless the information you have given be added such as temperature of calcination or sintering, ratio Cr to N, and as mentioned by Tyagi. So it is possible to give a different effect to those planes. 

Thank you all for the reply and sorry that I didn't provide enough details. I was talking about chromium nitride coating on polycarbonate substrate and 2theta-ω scan was done. Chromium was deposited as a adhesion layer followed by chromium nitride. The thickness of the coating would be around 1 micron. I appreciate your answers.

first guess (usually the most simple answer is the correct one): misalignement of the instrument or the sample (e.g. in height). A misalignement of the beam or sample with respect to the goniometer centre becomes more prominent with larger diffraction angles, whilst it is smaller (and sometimes not even noticable) with smaller diffraction angles. If you want, send me your sample and I'll measure on my machine.

Thank you all for the replies and for being generous to do the xrd scan but unfortunately i do not have the sample now. Can I know if the instrument misalignment will affect the intensity of the peaks too rather than just the position? I also want to add coatings on other substrates like polyamide and vinyl ester did not show this shift at higher angles. The depositions were carried out at 3 different nitrogen flows for 3 different substrates of polycarbonate, vinyl ester and polyamide. So totally there were 9 samples with 3 different polymers in one set of condition. Out of 9 samples, only the polycarbonate is showing the shift. If it is an instrumental error, won't that be shown in other substrates too?

I think, yes. The intensity of the (222) peak could be lower than expected (as e.g. derived from known structure and form factors), simply because you are not hitting the sample properly for max. (222) reflex intensity. If the peak positions are good for other samples, check if the one with unusual behaviour was not too low/high (I think, it should be too low) in z or simply re-measure it -- which obviously is hard if you don't have the sample anymore.

Normally after loading the sample I always correct for z. Thanks for your input.

Bragg-Brentano configuration.

I understood Anurag Tuagis question simply as "do you use a (post)monochromator (=3rd axis)"?

i dont think i chose a triple axis configuration.

Is it hard at this stage to say clearly if the shift at higher angle is due to strain because the strain info as derived from Bragg's equation suggests that at higher angles the shift will be more prominent? As the zero position is corrected before the scan and the shift is absent for other samples, can I say that the shift is more likely from strain?

No. At this stage you cannot draw a final conclusion.

With the angles you gave, for my taste the stress/strain would be quite big (depends on the material, though, but what I have seen so far, peak shifts due to strain were more in the tenths of degrees).

My suggested strategy:

0.) Get the sample again.

1.) Check alignment and re-measure.

2.) If results are the same, measure one more relevant crystal direction to confirm (then you can conclude sth.).

3.) Maybe anneal the sample and re-measure. If it was strain, it could be released by annealing.

I cannot see how one set of planes (e.g. 222) can be shifted without the directly related set of planes (111) also being shifted, regardless of strain effects etc.  So there must be another explanation.  As the previous answer (Wolfgang Kreuzpaintner) implies, these shifts (~2 deg.) are huge so one has to question whether both peaks have been correctly assigned, the first suspicion being that what is thought to be the (222) is not the (222) but another hkl reflection or an impurity peak.  Incidentally I don't know anything about the XRD/structure/absences for CrN so another (perhaps, silly) question is whether it  is known to normally show an observable (111) reflection anyway? 

I can imagine some explanations. 

1. As your sample is pretty thick, you should think of the probing depth at different angles. Naturally, you probe twice as thick layer at the larger 2theta. In case of strain or composition gradients you might observe such shifts. The profile of the peaks should tell more: for 222 you should have much-much wider peak in this case. 

2. Check how the tested area of the sample change at the two values of 2theta. Gradients (in strain or composition) in-plane can also cause peak broadening and shifts. 

3. Almost any type of deposition of CrN will result in compressive stresses. Provided your substrate is very soft, such configuration can result in wrinkling or buckling, even with much thinner films. I can imagine your film wrinkled after the first 100 nm and then got smooth again during further deposition. 

Have fun!

Sample height displacement from the center of diffraction circle cannot be ignored

Please try to adjust your alignment and then check it by a good standard. The shift at small angle is usually very much smaller than at high angle so you may have a small shift also at (111) plane but you have not noticed it .