I have synthesized Ca doped Tb1-xMnxMnO3 . It is said in literature that Ca can occupy Tb site or Mn site. i have tried to refine the crystal structure of Ca doped Tb1-xMnxMnO3 by rietveld refinement method. I have choose different sites for Ca during refinement. Since the rietveld refinement gives good results in both cases.How can I find that the doped Can goes to Tb site or Mn site?
Did you tried powder neutron diffraction ? The contrast (i.e. bj) between Mn and Ca and between Tb and Ca is large enough. Moreover, if you record data in the ordered magnetic state, you will observe a decrease of the magnetic moment of Tb or Mn due to the magnetic dilution.
Thank you for your answer. Yes I have tried neutron diffraction. the same problem has been found in The volume of solid solution first decrease up to a certain value of x then it increases. the increase in volume may be due to occupation of Ca on B-site and decrease may be due to occupation of Ca on A-site? Is there any precise technique which can help to find the exact position of doped ions? or any parameters in neutron diffraction refinement? which can solve such kind of questions more clearly?
Bond-valence analysis, which calculates the expected charge of the ions on a site depending on the distance of the neighboring atoms, might be helpful. Both Tb and Mn should be +3 in this structure, thus the presence of Ca+2 on a site can be expected to decrease its bond valence. Of course, the mechanism by which charge balance is maintained might also affect the results.
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