Unexpected Peaks in XRD: Causes Besides Doping?

  • Context: Graduate 
  • Thread starter Thread starter drizzle
  • Start date Start date
Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
Sign up Log in
4 replies · 6K views
drizzle
Gold Member
Messages
202
Reaction score
58
what possible explanation to an unexpected peak that may appear in an XRD pattern of a pure material [not doped, as far as I know the extra peaks that may occur would be due to the dopants], what causes, other than doping, could show alien peaks in a pure compound? thanks in advance
 
Physics news on Phys.org
drizzle said:
what possible explanation to an unexpected peak that may appear in an XRD pattern of a pure material [not doped, as far as I know the extra peaks that may occur would be due to the dopants], what causes, other than doping, could show alien peaks in a pure compound? thanks in advance

You need to explain what you mean by a "pure material". Is this a single-crystal throughout, or do you just require that it is made up of only one type of material that you say, is undoped?

If the material has something called a "superlattice", then that will show up as an extra peak. If it is made up of only one type of atoms, but it can have two or more different lattice structures, that that will show up as additional peaks. Vacancies and defects will also do the same. Etc... etc.

Zz.
 
thanks for replying ZapperZ, it's a metal oxide compound [in a powder form], this material has a number of knowable peaks each at a certain (hkl) plane [recorded in JPDS cards], however, a number of extra peaks show in the XRD pattern [none of them matches with the known peaks of this material], I thought of defects as a possible candidate, but it doesn’t sound reasonable, cause those peaks aren’t small ones [a number of them have high intensities], I could be wrong though...is the synthesis method of this material a possible cause to those peaks? [I mean to form defects in the material which in turn lead to those peaks]
 
Last edited:
If your starting materials used to create your compound didn't react completely, you will see peaks from them. Have you checked for those?
 
The simplest explanation is that there is a small amount of impurity, but it is a strong x-ray scatterer so there are large peaks in the measured spectrum.

Remember that the peak height only indicates the relative mass fraction if the scattering power of the compounds being compared are the same.

If you put a small amount of transition metal in graphite you'll primarily see the metal peaks.