I notice for a metal oxide when we we need this metal oxide to be doped , we must use doping with at least 8% wt in order to see some peaks belong to the dopant material in XRD pattern, other wise if the dopant was small less than 6% only we can see a shift in Bragg angle and the inter planar spacing.
It should not have happened that way. If it is so then there might have been Matrix effect which must have dampened the effect of dopent. Check the range of 2 theta value through which you scanned your sample under investigation.
Dear Mr. Habubi,
Not getting XRD peaks corresponding to impurity phase for low concentrations of the impurity is normal. There are several reasons for this. Many a times the impurity goes at substitutional cite and make a single phase as that of the host in such cases one may not see separate impurity phase and hence no new XRD peaks and a little shift in the XRD peak(s) of the host material and may be attributed to the strain/stress generated due to difference atomic sizes of the substitutional impurity and the substituted host atoms. But at higher concentrations of the impurity phase may be precipitated out due the concentration more that the solubility (substitution) limits. The impurity thus could form its own phase(s) in the form of some clusters and the XRD peaks could appear corresponding to such phases. In your case more than 6% could be such limit hence for the concentrations more than that (~8%) the phase starts precipitating out and you could see XRD peaks corresponding to that phase. I hope you could get the answer to your question. Good luck!
--- P D Sahare
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