Hello!
Let's imagine a glass network (silica-based for instance) and some crystalline nanosized (< 5nm) particles are statistically distributed through this network.
Indeed, by means of Raman spectroscopy, vibrational properties of these nanoparticles can be measured giving thus access to their crystal structural features. Provided the nanosize (< 5nm), vibartions of confined phonons are likely to be observed, and thus making Raman spectra interpretation more difficult (especially when vibrational bands from the glassy network -surrounding nanoparticles- overlap with vibrational bands from nanoparticles).
My question: are there any other experimental techniques that can be of a considerable value in determining the crystal structure of those nanoparticles?
Thank you so much ahead for your time and consideration!
Kind regards,
Hi,
I think HR-TEM imaging would be very useful in this application as silica is amorphous. In order to get more information CBED technique will help in this context, too.
All the best,
I agree totally with previous answer. Due to nanosize, you can't use X-ray diffraction since the diffractin peaks are hugely enlarged by size effect (see Scherrer formula). Thus you must use Electron Diffraction in convergent beam. In addition, nanosized particles can present a crystalline cell different from the one observed for large particles, or a short range order only...
I also agree with the previous writers, HR-TEM can do the job. In some cases EBSD might also be helpfull. The information depth of this technique is of the order of 5 nm. Maybe that the lateral measure is too small for this technique.
HR-TEM and TEM can be used as previously mentioned, but also you need to consider the thickness of real sample since the penetration power of SEM and TEM are limited. you may need to slice you sample into very thin film. Another interesting method might be using emission characteristics of NPs under beam especially if you NP is semiconductor such as QD. check you instrument for photo-emission detection. and EDS mapping may give some nice picture of NP. good luck.
Well you must perform an XRD, this will give you the crystal difraction of your material (there are some charts that has been theorically calculated) then use TEM, then analyze the image by aplying and FFT (fast fourier transform). This will show you the crystal arrange, you must determine the interplanar distances (d) in order to measure the angles and develop the equations to confirm there is the crystal mentioned by the PDF's of the XRD. Remember that the reciprocal net will give you the h,k,l parameters to confirm your crystal is near to the theorical calculations (there is always an error). Is not an easy work, good luck.
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