Please tell me the correct way to calculate FWHM. As someone has said that if fir peaks using Gaussian function, then it gives direct FWHM. But if we use lorentz or pseudo-voigt, then it is w not FWHM. What is the difference between these two terms? If these two are different, so please tell me the correct way of finding FWHM for XRD peaks. I want to plot WH plot to further calculate strain parameters.
I suggest to use a free package specific for XRD as FULLPROF suite for analyzing the profiles. The time invested in trying to work with ORIGIN would be more efficient if you learn to do with FULLPROF or any other. I recommend to treat XRD profiles with specific softwares that consider pseudo-Voig or Pearson VII functions for XRD peaks, assymetry, any many other features. You should take into account that most of the XRD profiles are measured with two wavelengths and the FWHM should be always refered to only one wavelength. As far as I know, ORIGIN is not able to do that. ORIGIN is a very powerful program but I don't recommend at all for XRD profile analysis.
Very simple. google it.
http://www.originlab.com/index.aspx?go=Products/Origin/DataAnalysis/PeakAnalysis
http://www.originlab.com/index.aspx?go=Products/Origin/DataAnalysis/PeakAnalysis
Mr./Mrs/Miss Gupta,
Why you do not try with Weibull distribution (attachment)?! You should use, however, a manual entry of the shown as attachment function and parameters via the "Edit function" option of the "Advanced fitting tool" option of Origin.
An example of treatment of powder XRD peak, using the mentioned distribution is given as attachment as well.
I would highly recommend to read some fundamental books about XRD in order to understand why different profile functions are used and why FWHM is changing with 2theta and how it is defined or described. Moreover, I hope you know which kind of strain you are approximate using WH plots, and that this model is a) quite old, and b) also very questionable since the assumptions made are not very general. Of course, if you do not have any imagination about the historical development you cannot judge the information a HW plot will give you, especially if you don't know what FWHM means. Therefore, don't do step two before step one.
I suggest to use a free package specific for XRD as FULLPROF suite for analyzing the profiles. The time invested in trying to work with ORIGIN would be more efficient if you learn to do with FULLPROF or any other. I recommend to treat XRD profiles with specific softwares that consider pseudo-Voig or Pearson VII functions for XRD peaks, assymetry, any many other features. You should take into account that most of the XRD profiles are measured with two wavelengths and the FWHM should be always refered to only one wavelength. As far as I know, ORIGIN is not able to do that. ORIGIN is a very powerful program but I don't recommend at all for XRD profile analysis.
I totally agree. You don't have to discover the bicycle twice! Therefore very powerful software has been developed in order to prevent a repetitive development of always the same problems, and often in a horrible quality.
The person advising you is not correct. The full-width at half maximum, is what it says it is the width of the peak at half its maximum intensity. Any function you use will give you a value of this, or you can just measure by hand if the fit is not good.
We'll have our dppa peak profile analysis tool updated and working soon, available at dMata.co.uk. Also my PhD was on peak profile analysis in the link below
Thesis THE USE OF DIFFRACTION PEAK PROFILE ANALYSIS IN STUDYING THE...
You can refer the link below to determine FWHM correctly. Maybe it will help you.
https://www.youtube.com/watch?v=2Nv7bJjm2Yk
Thanx a lot to all of you for your valuable responses.
Guirado Sir, I know Rietveld refinement is very good method for finding FWHM. I have used this using Fullprof software. One must know space group, approximate lattice parameters, lattice positions for doing Rietveld refinement. But what to do if one does not have these parameters ? As in my case, I have XRD data for irradiated samples, for which there is no literature to know even space group after irradiation. So what should do in this case? As I am new to this field, so I do not know much about finding space group from XRD data alone.
So I am trying to find FWHM using origin. But finding FWHM is a very tedious work from Origin too.
Dear Merry,
It is not necessary to use neither the Rietveld method nor the Pattern Matching (as it is called in Fullprof) to evaluate the FWHM of a peak. The FULLPROF suite (that includes a lot of programs) have a software called WinPlotr that allows you to fit individual peaks and get the FWHM of them. With this software you don't need to know the space group or the cell parameters. You must just introduce the initial peak position and width ant the software does the rest in a very easy way.
Thank you Guirado sir.
Sir I want to know one more thing. I have read that FWHM increases with theta. Is it so?
Sometimes when i do Rietveld refinement or peak fitting even using winplotr, FWHM gradually decreases with theta. So is it acceptable?
Always try to do full-width on a g (1/d) or d scale. Because yes otherwise the wavelength will have an effect; so for a size broadening (not expecting any increase in broadening for different peaks of different hkl) the full-width will change if in 2-theta but not in g. If you have Matlab you can use my code to fit your peaks http://www.dmata.co.uk/dippa and https://github.com/dMaterialia/DPPA. Also to convert between FW in two-theta and FW in g there are formula (also see my PhD above or http://dmata.co.uk/dppa.html). Sorry lots of plugs for me :)
To calculate FWHM for XRD peaks using origin. You can see it here
Link: http://bit.ly/2qvW3ZZ
I hope it will help you.
See this video
How to convert XRD files XRD data to excel or .raw to excel by Powdllconverter
https://youtu.be/xICBtXwzKLw
How to Calculate FWHM in XRD
https://youtu.be/WauGqgz3vy8
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