I want to know about the particle shape and either these are mono disperse or agglomerated.
At a first glance, I would suggest using TEM or even HRTEM (depending on the level of accuracy you want to get and on the average size of your particles).
You may easily get information on shape, crystallinity (also collecting the LEED patterns with the same TEM), and you may also have a rough but significant idea of any possible aggregation or ripening.
TEM is not strictly a statistical analysis tool... but you may collect several images from several points of your sample and just sort the particles for size and even shape.
If your particles are larger than say 30-40 nm in average you may also use FESEM (Field Emission SEM) that if properly used can provide you with a statistical distribution of size, above all when your nanoparticles are intrinsecally conductive.
Lastly, if you need information on size distribution in a liquid host, I would suggest light scattering techniques.
In all cases a key factor to get correct and satisfying results is expertise and ability of people performing the measurements and data analyses.
At a first glance, I would suggest using TEM or even HRTEM (depending on the level of accuracy you want to get and on the average size of your particles).
You may easily get information on shape, crystallinity (also collecting the LEED patterns with the same TEM), and you may also have a rough but significant idea of any possible aggregation or ripening.
TEM is not strictly a statistical analysis tool... but you may collect several images from several points of your sample and just sort the particles for size and even shape.
If your particles are larger than say 30-40 nm in average you may also use FESEM (Field Emission SEM) that if properly used can provide you with a statistical distribution of size, above all when your nanoparticles are intrinsecally conductive.
Lastly, if you need information on size distribution in a liquid host, I would suggest light scattering techniques.
In all cases a key factor to get correct and satisfying results is expertise and ability of people performing the measurements and data analyses.
.. you might also considering SAXS/SANS (small angle X-ray or neutron scattering). In this case you should get an idea about the clusters. Conversely, if you use XRD (for instance the Whole Powder Pattern Modelling) you can get quite a detailed information on shape, size distribution and defects of the coherently scattering domains. In most cases those can be assimilated to the nanoparticles. If you combine the two, you can have a very good idea about the agglomeration.
TEM can validate those results as well. I do not use it as a primary technique cause, as already said by Giuseppe, it is intrinsically not good from a statistical point of view and cause getting an XRD pattern and analyzing it is far easier! Plus, try to imagine if you have a mixture of magnetite and hematite nanoparticles and you want to obtain the separate size distributions of both ;) With diffraction this comes out in a straightforward way
You can use DLS for studying the state of agglomeration. TEM would be a good choice for surface morphology investigations.
Hi Ravi, I would suggest you as follows:
First go for FESEM/SEM for an idea size sand shape then go for TEM/HRTEM for size and size distribution of the nano particles. XRD and Selected-Area Electron Diffraction Pattern (SAEDP) will give you information on shape, crystallinity of nanoaprticles. If you want to know if particles are disperse or agglomerated you should do DLS analysis..
DLS is a good choice to study size distribution, dispersion and surface charge on colloids; also it has attractive advantages: is a fast analysis and can be an statistical tool. In regards with monodispersion, PDI value and zeta potential value can give you a clue on whether your particles are well dispersed or clogging under certain conditions (pH, temperature). Just keep in mind that using DLS requires some considerations regarding particle shape, so using a previous technique to obtain a morphology reference like microscopy can help you on relying on DLS as your primary measuring tool.
http://www3.nd.edu/~rroeder/ame60647/slides/dls.pdf
We can investigate the morphology of a surface with nanoparticles using scanning electron and force microscopy techniques. Moreover, microbeam grazing incidence small-angle X-ray scattering (μGISAXS) experiments reveal information from the inside morphology that could not be obtained via microscopy techniques. In addition, photoluminescence (PL) spectroscopy gives information of the photoelectronic properties of nanoparticles well prepared and high heated.
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