Say we have an XRD pattern that shows peaks for both (111) and (222) planes. Does it mean the crystal has a property that a similiar material that shows only the (111) peak doesn't have?
Thanks in advance
Dear Rafael Spaziani ,
your samples have different types of crystal structure.
The selection rules (allowed or forbidden reflections) are due to the property of the structure factor.
See for example:
http://groups.mrl.uiuc.edu/chiang/czoschke/diffraction-selection-rules.html
or
https://en.wikipedia.org/wiki/Structure_factor
or
https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Introduction_to_Solid_State_Chemistry/06%3A_Recitations/6.16%3A_X-ray_Diffraction_and_Selection_Rules
So for example you will have for the FCC lattice (111) as well as (222) peaks present in your pattern (h, k, l all even or all odd),
but for the BCC lattice you will only have (222) peak but no (111) peak;
(h+k+l) = even -> allowed reflection; (h+k+l) = odd -> vorbidden reflection
Please see also the case for FCC Diamond:
here you have (111) allowed [(h, k, l) all odd]; but (222) forbidden [(h+k+l) not equal to 4n]
Best regards
G.M.
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