I am working on characterizations of mullite needles, which exhibits nano-scale size, in order to investigate their Al/Si ratio. The needles possess 100-200 nm long and about 20-50 nm diameter in average. And the needles are embedded in a silicate-glass matrix.
I have done SEM-EDS but I could not get the Al/Si ratio since the EDS signal were not indicated mullite characteristic. It supposed to have large interaction volume and the obtained signal included both mullite and glass matrix. I also performed FIB/SIMS which is about 10 nm of interaction volume, again I could not get the signal.
I am thinking what can I characterize the needles chemically to find out the Al/Si ratio.
Any suggestions will be really appreciated
I would like to give you some advice. I hope it might be helpful.
The following ideas based on the premise that your samples contained only one kind mullite.
1. How about you etched the samples before you did SEM-EDS characterization since glassy phase could be removed by HF (3 wt% or 5 wt% for 60 s)?
2. You might get the Al/Si ratio via a combination of XRF (nearly a full oxide component could be given) and XRD (the content of each phase could be calculated via Rietveld method).
3. FE-SEM technique might be more suitable since it could give the relative content of surface element distribution.
4. If your samples contained only mullite and glassy phases, could you etched sample powders (fine enough) with HF, then washed and dried the samples for XRF detection (I was not quite sure whether it would be useful)?
STEM technique proposed by Alexander is good . I think also can be used diffraction technique of polycrystalline materials.
Technique proposed by Alexander Meledin is good. I think also be used diffraction technique polycrystalline materials
Following up on what Jose said, you might want to consider Pair Distribution Function analysis on your material.
Dear Alexander Prof Jose and Tahani
I really appreciated your suggestions, I will try to use the STEM.
Dear Kun
You are so right, actually I did etched the sample using HF but the result was what I mentioned. Unfortunately, the sample also contains some amounts of quartz; therefore, neither XRD nor XRF can differentiate the Si in mullite/ and quartz forms.
Dear Vijay
Thanks for your advice but I have no idea about the Pair Distribution Function, I may spend more time to read it.
Any more suggestions are very welcome.
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