Hi everyone! Thank you in advanced for any help given. We want to perform the analysis of mineral deposits on our samples, by evaluating the presence of calcium phosphate through the analysis Ca and P deposits (atomic percentages). We are obtaining a graphical P signal. However, no numerical data is observed.
We are currently using HITACHI S-3000N, Japan (SEM/EDX) and our samples are coated with gold (120 seconds).
Any advice or recommendation will be appreciated! Thank you and have a blessed day!
Dear Maria, I guess the problem is that both the P K-alpha as well as the Gold M_alpha almost have identical X-ray energies, and thus a correct assignment to the peaks is almost impossible without a deconvolution of the spectra. I would propose to avoid the gold coating and to repeat measurements without coating. Imaging might be a bit more difficult without conductive coating, however EDX will work hopefully ... Good luck, Dirk
By chance, I just had the inverse problem: I tried to find very small traces of Au, hoping for Au M-alpha at 2.123 keV (see Dirk's answer). This is, in the low energy range at least, the most intense EDX peak from Au. Indeed, I first had to make sure that my sample was totally free of P (2.139 keV). There are also some other elements (metals) that could be problematic.
Btw, EDX works very nicely with ESEM, so I usually leave my samples totally untreated, and image them in 100 Pa (or more) of water vapour. If you have no ESEM option, and you need no imaging, you, too, could try without coating, as suggested by Dirk.
One more point, which you might know already: Never *ever* trust your EDX % for C and O. You will always either deposit or remove carbon, and often also oxygen. I would guess you are interested in the P/O ratio. If so, you can test this with EDX of a well-defined sample of a stable phosphate, under exactly the same conditions that you use for your sample.
If possible
- use FESEM
- applied HV= 10 kv
- Examination of the same sample, but with different compositions
I sincerely appreciate (so much) the time taken to go through my question and your very valuable contributions. I think your explanations clarified my doubts and I think it will be the solution for the problem that we have had. Extremely grateful for your time and help! We will follow your recommendations and I for sure will let you know if we managed to solve it. Many blessings!
- Badges
- Science topic
- Similar topics
- Engineering
- Materials Engineering
- Coating