I did Scanning electron microscopy (SEM) and then EDX analysis of my Sr based apatite (by wet chemical route and calcined at 1100 degree for 12 hours) and expected the ratio of Sr/P to be less or equal to 1.67. But it turns out that the data provided (in atomic and weigh %, confirmed by both) comes out to be larger around 1.84 for 6 um range scan image. Why is this happening and the reason for it?
Just a guess: The excitation volume is larger than the particle size or layer thickness and the basic assumptions of quantification are not met.
It seems to me that your results are not so bad, you should also consider that the errors in the EDS determination are not small...
Anshul Sharma,
ould you provide the actual data? It would help to see the actual image and spectra.
Which lines are you using for analysis?
How smooth is the surface?
If you are using Sr-K and P-K, geometry will be important. If you are using Sr-L, both elements will be affected similarly.
Are you sure you synthesised a perfect apatite with 1.67 ratio? Are you sure your specimen was properly prepared and mounted (I second Warren Straszheim's request). It is useful to obtain a piece of apatite with confirmed stochiometry to use as a standard.
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