We have observed most intense peak at (101) for cobalt doped ZnO synthesized using sol gel process.
Your films are probably textured.. so u get only one peak. Regrading nano powder it s not possible to orient in a particular crystal direction..
But the most intense reflection will always be (001) or it can be (101) or (002) sometimes.
An oriented film, no matter if its nanostructured or single crystalline will show texture (or preferential orientation of crystals, an equivalent term) so intensities will not reproduce the ones observed for a random powder.
If the film is oriented along 00l (or 000l equivalently) then 002 reflection will be the most intense in the pattern (001 will remain a systematic absence), if not the only visible (additionaly to 004 and 006 if you go high enough in 2theta) in the pattern if the degree of orientation of your film is high.
Films grew on a seeded (Zinc acetate or any other spin coated solution heated over 100deg C) substrate usually show a columnar (hexagonal rod like) growth. These films in XRD show a intense peak at 0002 direction. Diffraction peaks in all other directions are almost absent.
On the other hand, in the powder, although all the particles are rod like (grew in 0002 directions), the rods are random in orientation. So all the planes can be seen by x-ray and all possible diffraction peaks can be observed.
So in powder, even if the particles has an preferred growth direction, all possible peaks can be seen where as in a film preferred growth will generate textured film which only will diffract by 0002 planes.
One more thing, Co is doping and small doping level it should not affect the crystal structure of ZnO.
Hope this will help.
If this is your experimental pattern you have very little preferential orientation of particles, the intensities look pretty close to random ZnO powder.
Shahid,
This is a random Pattern. If you want to see how aan oriented ZnO pattern looks like please see one of my publication in Jpn J Appl Phys. Please, use this link:
http://jjap.jsap.jp/link?JJAP/52/05DA09/
You can also see the pole figures and SEM figures which will tell you how good they are oriented.
Good luck
If the relative intensity of the (002) increases with respect to the powder, that means that you can have some preferential orientation and that can be calculated with a Rietveld refinement of the structure. However, the appearance of this pattern doesn´t correspond to a highly orientated film, as was mentioned above.
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