I agree with Kenneth M Towe

Dr. Kenneth has rightly mentioned - XRD on different size fractions along with the petrographic studies will help in proper identification.

You may see the following - these are useful

https://www.researchgate.net/post/In_XRD_how_to_identify_which_peak_is_which_element_in_a_known_crystal_edited_question

Materials Characterization Using X-ray Diffraction

https://www.iitk.ac.in/acms/doc/XRD_AG%20NPG.ppt

http://web.pdx.edu/~pmoeck/phy381/Topic5a-XRD.pdf

Regards

XRD TECHNIQUE is based on finding out the d-spacing of a particular crystal structure of a mineral.

So when you obtain a diffractogram though there are many peaks...there will be certain characterstic peaks for each mineral based on which you can identify the the mineral

An amorphous material can not be identified by XRD, similarly a metamict mineral will be reheated to a particular temperature to regain its crystal structure, so that the mineral can be identified

If a particular mineral crystallize in more than one form...they can be distinguished based on their structure...

for example...rutile, brookite and anatase.

Thank you all, To be more clear in my question, in my analysis, I noticed that the Xpert software identifies the main peak as Monazite, which is a mineral generalization. However, if I need to know which phase in particular the peak corresponds to what technique do I need to use, because the mineral monazite may denote any phase namely, in my case, CePO4, NdPO4, LaPO4 or PrPO4 or Th3(PO4)4. Do I need to go for an advanced equipment that can distinguish the peaks individually corresponding to all the major phases in the mineral.

Dear Kenneth,

The above information for only Cerium Phosphate, however other phases?

Dear Sanjith,

May be Rietveld analysis will solve your problem. In this technique, you may insert different CIF file such as (( CePO4, NdPO4, LaPO4 ,PrPO4 or Th3(PO4)4 )) that you believe related to your scanned pattern. When you hit analysis button, the atomic position of the CIF file will match the corresponding peak position. I hope you get the idea.. give it a try.. feel free to contact me if you need further info..

good luck

mohammed

Dear Sanjith, the XRD of minerals is not a physical or chemical problem; is a mineralogical problem for which you can use physical techniques as XRD but also SEM, TEM, thermal analysis, IR spectroscopy, optical microscopy; and chemical ones as microprobe, fluorescent analysis, etc. The XRD is perhaps the most useful, but the expertice and integration capacity of the scientist is the best tool. The phosphates are ones of the more complex mineralogical families because they have a lot of isomorphical substitutions of the anion phosphate by others ions (OH, F, etc.); and also cathionic isomorfism . Years ago I deal with the family of apatites in Cuban phosphorites and it was very difficult. The main problem is that many isomorphic species have quite similar XRD patterns.

Be patient, wise and smart, because your deal is hard but amazing.

Dr. Carlos has scholarly explained the problem.

Regards

Dear Sanjit, I strongly agree with the advice already given that you, for a proper characterisation, must use complementary techniques, in particular methods that allow elemental analysis (e.g. XRF, XPS). Minerals are distinct phases, while mineral samples might be physical mixtures of several phases. Then, on top, each mineral/phase may be a solid solution. Each phase gives its own pattern, but you cannot from XRD easily find out what the actual composition is!

From your statements I read that Monazite has the fundamental composition MPO4, where M= Ce, Nd, La, Pr...). Irrespective of details concerning M, the pattern as regards its lattice fundamentals remains the same; there are only variations in lattice parameters and intensities. Therefore, I doubt that Th3(PO4)4 would give a similar pattern, unless there are totally 25% vacancies on the cation sites to conform with the overall MPO4 description. (I do not know these systems.)

The strategy is to index your pattern according to the description of the structure type, but since it is monoclinic this is in itself difficult, because you will have various indexing possibilities for a given d-value if you do this blindly. As suggested (Towe), compare with existing diffraction files to sort out weak intensities.

For deeper insight, elemental analysis is a prerequisite here for finding out what metal dominates (M). You can then calculate a pattern where only that element constitutes the metal part of MPO4 for getting a rough idea about what intensities you should expect. The exact values of the atomic coordinates are not crucial here; you can take from the literature for any variant. That procedure should leave you a fair picture of whether you also have another phase present in your sample (because you then also get unindexed lines, that in their turn have to be explained...). You cannot get any idea at all concerning the metal distribution within a phase from a diffraction pattern; I am sorry but that is the fact. On the other hand, follow the advice: do not stick to a single technique -- you learn a lot from getting scientifically broader!

Good luck