I have prepared films of ZnO and ZnO/MWCNT nanocomposite by doctor blading and then annealed these at 450oC for half an hour. Nanocomposites are prepared by direct mixing. After taking XRD I observed a lower angel shift in Zno/mwcnt film with respect to ZnO film. What will be the reason for it?
It should be due to smaller particle size. But I have no idea why this happens. The reason for shifting can be explained as follows: Since 2θ decreases to lower values, cosθ increases. According to Scherrer approximation particle size D(nm) decreases. You should search for the reasons avoiding particle growth during your reaction.
I dont know doctor blading process. Below link considers about the technic.
http://link.springer.com/chapter/10.1007%2F978-0-387-88953-5_10
The term "binder" should be the key parameter: It covers around the nanoparticle and prevents it from agglomeration. So you obtain smaller grains.
please see the limitations of debye-Scherrer equation
MWCNT may cause a strain in the ZnO
Lower angle shift in Zno/mwcnt film with respect to ZnO film is all right but I am interested to know the angles in both the cases and the shift in the degree.
OMKAR SINGH KUSHWAHA Sir my peaks for ZnO 32.04,34.8,36.58,47.96,56.9 and for zno/mwcnt are at 31.16,33.86,35.66,47 and 56.08.
i guess
is there any zinc carbonate?
annealing at 450 degrees - some guess
Are you annealing ZnO and ZnO/MWCNT in the same temperature or only the composite ZnO/MWCNT was annealed?
since a shift in to lower angles in 2theta means that you have larger lattice spacing in your crystallites, assuming otherwise identical diffraction patterns. Reasons therefore could be tensile stress (the MWCNT matrix "pulls" on the crystallites) or a solid solution of carbon in the crystal structure. Grain size is not a factor here since it manily contributes to peak broadening/sharpening when decreasing/increasing and no shift in the diffraction pattern.
if the same peak broadens it has to do with deviations in the Debye Scherrer equation
Appearance of peaks near is the new compound
Carbon will be oxidized to carbonate in 450 degrees in air
Thank you all of you for your valuable answers...i heated the ZnO and its composite at same temprature. i have done same for TiO2 and TiO2/mwcnt composite but there is no paek shifting in that case...
Is this a single experiment result? If so try the procedure once again. It seems to me that there is about 0.9 shift in all the angles.Any factor affecting the lattice spacing is not expected to shift all of them with the same value.
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