I have synthesized zinc oxide nanoparticles by physical method (sputtering) direct interaction of plasma with zinc target and it is done in atmosphere. The sample were prepared at different time.Now xrd analysis confirms zinc oxide nanoparticles but peaks are shifted at different plasma discharge time? Kindly let me know the possible reasons of peak shifting in sample 1 at 15 minutes interaction and sample 2 with 30 minutes interaction.
Dear Jamil Khan ,
The reason for the shifting of XRD peaks, in general, can be any of the following:
1. Change in the chemical composition. The peak shifting due to the chemical pressure is caused by the change in lattice parameters as per Vegard's law and Shannon-Prewitt radii.
2. Instrumental error during the measurements (in the form of zero or displacements). But this effect should be common for all of your samples if the XRD measurements are performed on the same diffractometer, without any change in calibration.
3. The expansion or compression of the lattice (most likely in your case) caused by stress or temperature.
In any case, I would suggest you to perform Rietveld refinements of your XRD patterns for detailed analysis. You can get most of your queries resolved from the refinements. Microstructures parameters (crystallite size and local random lattice strain) generally result in the broadening of the XRD peak and do not contribute to shifting.
Regards,
KP
Dear Jamil Khan ,
The reason for the shifting of XRD peaks, in general, can be any of the following:
1. Change in the chemical composition. The peak shifting due to the chemical pressure is caused by the change in lattice parameters as per Vegard's law and Shannon-Prewitt radii.
2. Instrumental error during the measurements (in the form of zero or displacements). But this effect should be common for all of your samples if the XRD measurements are performed on the same diffractometer, without any change in calibration.
3. The expansion or compression of the lattice (most likely in your case) caused by stress or temperature.
In any case, I would suggest you to perform Rietveld refinements of your XRD patterns for detailed analysis. You can get most of your queries resolved from the refinements. Microstructures parameters (crystallite size and local random lattice strain) generally result in the broadening of the XRD peak and do not contribute to shifting.
Regards,
KP
The peak shift can be due to the formation of different crystal structures, chemical composition, and defects which can generate when films are deposited for different plasma discharge time.
You can also check for the stoichiometry of ZnO. As the deviation from this ratio can arise lot of defects and distortion in the basic structure. This will help you to have a better idea about what is happening for different plasma discharge time.
Regards
Juhi
Dear Jamil Khan
If I assume that all your synthesis parameters were the same, one can explain the peak angles shifted as the plasma treatment times increases is due to the increasing of the strain within the crystals. Please note that the accumulated strain energy is also a function for temperature as the strain energy in the high temperature system may faster relaxed than the lower temperature system. So if you decide to get non shifted results with different treatment times you should compensate with appropriate system temperature increase.
Best regards
Dear Jamil Khan
peak positions are affected not only by the above factors (measurement geometry, chemical shift etc.), but also by the size of the crystallite domains and the presence of microstain in them. It is certainly far better to use the Rietveld method and evaluate changes in the magnitude of lattice parameters and the size of crystal domains than the peak positions themselves.
Jamil Khan
Peak shifts can occur due to some of these reasons,
a) Crystallinity of the material concerned ( Amorphous/Polycrystalline/Crystalline)
b) Crystallite Size (Peak Broadening)
c) Crystallite Stress and strain (Micro/Macro)
Rietveld analysis will be helpful
Factors affecting the relative intensity of the peaks or diffraction lines can be due to,
a) Polarization factor b) Structure factor c) Multiplicity factor d) Lorentz factor
e) Absorption factor f) Temperature factor.
Hope this helps to some extent
Thank You
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