I have synthesized transition metal phosphates and characterized it with XRD and TEM techniques. The TEM analysis shows that the material is not in uniform size. TEM EDX is also not showing the accuracy, probably due to non-uniformity and requiring less quantity of the sample during the analysis.
Hello. The most important case for TEM EDX is the thickness of the sample.So what is the size of your sample? You said they are not in uniformed size, so maybe choosing the smallest ones will be better. And why did you say the result is not accurate before you have a qualified result? Besides, SEM EDX do not require small samples. Maybe you can try it and compare the result with the TEM ones. Wish that would be helpful.
As per my suggestion, the better way to quantify phosphorous in metal phosphate is ICP analysis. You may dissolute sample through proper procedure and quantify phosphorous content and metal content through ICP. In your case, I feel ICP will be more precise technique.
Hello Mr. Yifei Xu. The particle size of my sample is in the range of 10-90 nm. How can anyone separate/pick smallest particle for the EDX analysis? For comparision, I performed same sample analysis for two times and got different result.
Thank you Mr. Bhaumik for your suggestion. I am agree with you. But the problem with my sample is that it is insoluble in most of the solvents.
For ICP analysis only the organic part has to be digested in an acidic medium. Your sample need not to be soluble in it. Rather, the metallic component in ppm/ or ppb will be detected through ICP.
There are standard protocols for acid-treatment and sample preparation for ICP. You may like to google and find out most apt for your case.
If you want % composition and elemental analysis then best option you go for XPS (X-ray Photoelectron Spectroscopy OR ESCA) analysis, provided that you prepare the sample too homogeneous! XPS is a surface analysis technique and can detect only up to 10 nm depth on surface of sample! XPS can detect any element except H and He in the periodic table. XPS can tell you what is the oxidation state of your phosphorus which in turn will be helpful for confirmation of phosphate formation too with quantity!
I am agree with sagar patil suggestion. I will add another technique to test your sample by Electron probe micro-analysis (EPMA) . Here the WDS (wavelength-dispersive spectroscopy) provide more accurate and to the depth information about sample composition..
Hello. Then my advice is that you put a large aggregation of your sample on the silicon substrate and do SEM-EDX analysis. If the aggregation is big enough( more than 10um size and thickness), the result will be much more accurate. Remember to sputter some coating (like Au/Pd alloy) on your samples if it is not conductive, which will make the result better~~~
Thank you all for the nice discussion and opinions shared....Your respective suggestions are well noted and much appreciated.
maybe it is too late, but did you think to perform simple 31P NMR CP-MAS (or MAS) spectroscopy ? If you have no paramagnetic centers close to your P atoms, this will allow you to characterize the chemical nature and the content of phosphates in your materials. Otherwise, you can also use XRF (X-ray Fluorescence Spectroscopy) that does not require solubilization of your samples.
Thank you Prof. Villanneau for your suggestion to perform 31P NMR CP-MAS and XRF. My objective is to quantify the Phosphorous/phosphate content in the synthesized material. In my knowledge 31P NMR CP-MAS will provide qualitative information about the sample. As far as XRF is concerned it would be best method but there is a drawback of high quantity of the sample requirement (about 1 g at least) for the quantitative analysis.
OK, I believed that your goal was to quantify the different P atoms in you materials. In that case you could compare the integration ofthe different peaks of the different P atoms. For XRF, I think that there is now spectrometers that use less than 300 mg of products. The main advantage is that this is not a destructive method so that you can recover your sample. Furthermore, since this is a "massic" method, you don't have any particular treatment for your sample, on the contrary of XPS for instance which is very sensitive to impurities...
Thank you Prof. Villanneau!
Yes Sir, absolutely my goal is to determine %P content in my material.Your valuable suggestion is much appreciated. I will try to do either of the method that you suggested.
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