I am observing the shift in peaks in a mixed phase system (2 phases). I observed the peak shifting is more at higher angles i.e if it is 0.2 upto 2 theta =30 degrees which increases to 0.4 towards higher 2 theta value. What is the possible reason for this? In addition I would like to ask is it possible to have peaks corresponding to high 2 theta value without seeing significant intense peaks (by any means) .
This is what you should observe. You can calculate the expected changes from the Bragg's law. If all lattice parameters change for example by 1%, the peak at ~20 degrees will shift by ~0.2 degrees and the peak at ~40 degrees will shift by ~0.42 degrees.
Thank you Alexander B. Missyul’ Sir. Can you please explain how to understand it in terms of structure.
Alaka,
It should be easy to see if you differentiate Bragg's Law. That is,
(Delta)(theta) = -2 (Delta)d/lambda * tan(theta)
So for a given change in the d-spacing, the change in theta increases as theta [or more specifically, tan(theta)] increases.
Also keep in mind that in the formula (Delta)(theta) is in radians.
Thank you D. A. Walko sir. Can you please in addition answer my second query that if is it possible to observe the higher 2 theta peaks without observing the lower intense peaks by any chance.
Sorry, I'm not sure I understand your second question. In general the higher-angle peaks will have their intensity reduced because of thermal oscillations, described by the Debye-Waller factor. Is that what you are asking?
No my aspect was different but your answer cleared that query .thank you sir
Yes if the cell shrunk, simply by lowering the temperature or maybe in your case due to strain. The difference will be more prominent at higher angle.
Are all the peaks shifter or only partial?
No sir not partially.All the peaks shifted and higher angle peaks shifted more. Can you please tell why partial shift of peaks occur and one more thing i would like to add is uniform shift of peaks can be caused by meaduring instrument?
Would u pls attach the patterns? Did u performed refinement to your data?
https://www.researchgate.net/publication/221984033_Synthesis_magnetic_properties_and_X-ray_analysis_of_Zn097X003O_nanoparticles_X_Mn_Ni_and_Co_using_Scherrer_and_size-strain_plot_methods
Article Synthesis, magnetic properties and X-ray analysis of Zn0.97X...
https://www.researchgate.net/post/What_is_the_best_method_used_to_align_the_diffractometer_plane_axis_with_respect_to_the_incident_beam_direction?_tpcectx=profile_questions
The system I have prepared is Bi2Fe4O9. I have attached the XRD plot alongwith this answer. The low angle peaks are getting shifted by 0.2 degrees compared to standard while high angle peaks are shifted by 0.4 (approx.). Further the background noise in the sample is more which is constraining me to understand the phases clearly. In addition there are some intense peaks at higher angles which are spurious to me. So I would also like put another question as to how to reduce the noise and is it possible to get distinct peaks w. r.t. background by taking XRD for a longer time.Kindly suggest.
- Beware of fluorescence from Fe with Cu target.
- Index the XRD pattern to the best of your ability.
- Use Rietveld analysis.
- Post data in Excel format.
It is fluoresence effect of Fe due to Cu-anode in ur pattern. Unless u had energy dispersive detector or monochromator this kind of pattern will remain the same even u change ur instrument setting.
We cant do much if u attach picture because it's important to zoom in and out to see the details. And as mentioned earlier that the shifted toward higher angle can be by the strain or lattice distortion.
Thank you Ravi Ananth Sir. I am using Fullprof software for Rietveld analysis because this is a mixed phase system its difficult to solve the structure. So kindly suggest if by any means it is possible.
Maykel Manawan Sir . I will certainly process the image and get back to you .
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