I am looking for help with presenting XRD data for publication.I have two main queries, first is how to accurately identify peaks, and second refers to choosing which peaks to label and discuss, as well as the range on 2-theta to present.
Attached is the XRD of my latest investigation. It covers doped-BTO thin films on platinum covered Si substrates, which have been annealed over different temperature ranges(550OC to 750OC). To accurately identify the peaks, I use the software Mercury to discern the powered diffraction from .cif files. This gives me the (x,y,z) peak co-ordinates at 2-Theta values. Using these values, I have been able to accurately label the four major peaks appearing in all data plots I.E.(1,1,7), (0,2,2), (2,0,12) and (1,1,15). While I am certain those points accurate are correct, I am uncertain about how to label the points that peaks appear above 2-theta = 50.
According to Mercury, the two peaks that appear at 54.78595 and 56.55 are closest to the Bi4Ti3O12 peaks (2,0,19) and (4,0,3) which appear at 54.592 and 56.55 respectively. The (4,0,3) peak is quite accurate however the (2,0,19) has an entire 0.193 degree of difference. Is this an acceptable divergence, and is this the best method for identifying peaks?
The second thing I would like to discuss is choosing which peaks to actually label and discuss in the publication. I find that the amount of peaks and the 2-theta range covered by most people when reporting on this material varies significantly. What is the standard for accurately reporting XRD data? Should I just label the largest, significant peaks? or should I label all my peaks and present the entire 2-theta range?
Many Thanks
David Coathup
Usually in a diffraction pattern you must identify all the peaks in order to know how many phases are present. Once you are fully identify the phases you must performed the indexation of not reported phases; for reported phases you must compare your data with the references.
In the attached figure there are many not identified peaks that needs to be solved in order to asure that not secondary phases are present in your films.
Best regards,
Pedro
Dear colleague David Coathup,
Have a nice time and good day.
Herein fined two tutorial XRD attached files may help you.
Yours
A. EL-Denglawey
Dear David Coathup,
Rietveld refinement will probably solve the problem.
:)
You can also place on the figure the bars of peak positions as reported in the JCPDS card of your material. However, first of all, you should have in mind the purpose to draw this figure and what you want to demonstrate with it.
Give the name of diffractogram ie, Fig.2 XRD plots for .... Legends: o = ....., x = .... and the last you need to give the reader what is the wavelength you used. Indexing all peaks by search match method . You can use PCPDF WIN. There are many data in that software. If you are not sure about specific peak just put sign uk (unknown) on the top of that peak. It is common to put uk in XRD plot even in published paper.
There is also criteria for maximum limit of d spacing and not 2 theta, between model and your data. Delta d = absolute value of (d data - d model) = 0.01 Angstrom. The last you can refine data by using Rietveld method. To execute the refining you can use software as GSAS, Rietan, Rietica etc. Hope can help.
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