Usually, I mix silicon nanocrystals with polymeric compounds to create a nanocomposite for the purpose of studying changes in the photophysicsl properties. The problem is that I am still having trouble knowing the concentration of the silicon crystals added to the mixture. I hope to help me in whatever method you think is good in determining the amount of silicon crystal in the mixture.
With appreciation,
Mahmud Sefannaser
First there is a lot not shared, but I would start with the easy and see what works. For example, depending on the polymer you might try UV-VIS spectroscopy. If there are characteristic peaks for the nano-crystals and polymer then some basic ratios may be learned. If the crystals abs around 350nm and the polymer around say 700nm then it might work. If they share peaks then that becomes an issue.
XPS offers atomic concentrations of surfaces, you might also get an idea of ratios from maybe comparing Si:C concentrations for crystal to polymer.
If the weight fraction of nano-crystal is sufficient then maybe a sort of polymer dissolution and washing to then discern wt% ratios, unless the synthesis ratio is no where near possible to measure by weight.
Dear all, these free access documents are very helpfull. My Regards
https://doi.org/10.1016/j.surfcoat.2013.04.021
DOI: 10.5772/intechopen.86508
Mahmud Sefannaser
First, you need to determine the crystallinity of the silicon nanoparticles. Possibly the binder interacts with the crystalline silicon surface and transforms it into amorphous or other product. This can be done using the HRD. Secondly, the silicon content can be determined using an attachment to SEM, XPS, chemical elemental analysis. Perhaps the silicon of your composite will dissolve in hydrofluoric acid. Then the silicon content can be determined by a simple gravimetric method.
Thank you all.
Dear Jhon, you mentioned that "If there are characteristic peaks for the nano-crystals and polymer then some basic ratios may be learned." Could you please explain this part a little bit more?
With appreciation,
Dear Mahmud Sefannaser ,
Can you explain how do you build your composite.
It is so when you synthesize certain composite material you start with measured quantities of the components. If this is the case you know apriori the mixing ration between the different components of the complex.
You can use the absorbance of a specific wavelength to determine the content of the silicon.
Normally polymers are widegap and therefore they are transparent to the light with near infrared which is absorbed in silicon.
Then if you use light with wavelength of about 0.9-0.8 wavelength you can get information about the effective thickness of your silicon in the composite.
You can build yourself your spectrophotometer using LEDs as we introduced in the paper: Article LED Based Spectrophotometer can compete with conventional one
Best wishes
Thank you, Abdelhalim. The silicon nanocrystals that I used with the monomers are in colloid form, so I do not know exactly the concentration. I’ll try your method to determine the concentration.
Švrček, V., A. Slaoui, and J-C. Muller. "Silicon nanocrystals as light converter for solar cells." Thin Solid Films 451 (2004): 384-388.
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