Happy new year.
envoyé : 6 janvier 2023 à 12:36
de : Frank Girgsdies <girgs...@fhi-berlin.mpg.de>
à : KULDEEP SINGH <2019phdph...@curaj.ac.in>, rietveld_l@ill.fr
objet : Re: refinement
Dear Kuldeep,
First of all, a refinement (I suppose you mean Rietveld refinement?)
requires a crystal structure model, which in turn requires that you have
a rather precise knowledge about the identity/composition of the
crystalline phase you want to refine. XRD is not an elemental analysis
method, and perovskite structures can be formed with many, many
elements. Unfortunately, you forgot to mention what elements your
material is composed of.
I tired an identification anyway, using the latest edition of the PDF-4+
database. However, despite the fact that the pattern looks definitely
perovskite-like, there was no match close enough. Trying to tune the
lattice parameters of some better candidate structures revealed that
something is weird about your pattern, as the positions of related
reflections do not agree with each other.
Then I tried to shift the pattern on a trial-and-error basis and found
that it has in fact a severe zero shift of more than 0.4 degrees 2theta.
It could also be a serious sample height (a.k.a. displacement) error,
since these two errors are rather similar in effect. However, in order
to refine a displacement correction, I would need to know your
goniometer radius.
I performed a Le Bail fit assuming a GdFeO3 type structure (in setting
Pbnm) and obtained a reasonable fit yielding the following lattice
parameters:
a = 5.26617(12) Å
b = 5.62135(16) Å
c = 7.48743(19) Å
zero error = -0.4428(8) deg. 2theta
With this zero error information, I went back to the PDF search.
Based on that, my best guess is that your sample could be Ho(Cr0.5Mn0.5)O3.
Best wishes and Happy New Year,
Frank Girgsdies
On 23.12.2022 06:16, KULDEEP SINGH wrote:
Hi all,
please help to refine this simple data of perovskite i am stuck in it.
angle 20-80
step size 0.01
wavelength 1.5404
*Kuldeep Singh*
*Research Scholar*
*Department of Physics
Central University of Rajasthan
*
*Bandarsindri-305817*
*District-Ajmer, Rajasthan*
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