What are the analytical techniques to decide whether particles are of nanometer size? Whether the observations made from SEM alone are enough to say that they are nanoparticles? Also, what should be the range of sizes to decide that the particles are NPs.
Generally, below 100 nm is defined as a nanoparticle. Sometimes a value around this can be considered as a nanoparticle.
SEM and TEM can be used to identify the nanoparticle visually.
Another important characterization XRD can be used if the sample is crystalline, which can confirm the nano size of the crystallite with 100% assurity and trust. This can actually tell the exact size of the particles through calculation.
Sukhendu Sadhukhan XRD (Scherrer) determines crystallite size and not particle size. A quick visual test for systems stable in aqueous media is simply to observe if any settling is taking place, if the system is cloudy and so on. A true colloidal solution should be transparent (could be colored) with no settling taking place.
Thank you Alan F Rawle sir.
Can you please explain the terms
1. Particle Size
2. Crystallite size
3. Grain size
in this context?
What are the difference and relations between them?
If XRD gives the crystallite size, then what is the name of the parameters obtained from TEM and SEM?
Sukhendu Sadhukhan A little work with the Search tool on RG will answer your questions. There are many questions of this type:
https://www.researchgate.net/post/What_is_the_difference_between_crystallite_size_grain_size_and_particle_size
https://www.researchgate.net/post/What-is-the-difference-between-crystallite-size-and-grain-size-Is-the-both-terms-are-same-for-all-materials-or-different-for-different-materials
SEM gives you some 2D indication of a 3D particle (the z-axis is often 'forgotten unless some form of confocal technique is employed). TEM is dependent on the sample preparation and everything coming from a microtomes or sectioned sample is an artifact. Take a look at:
https://www.researchgate.net/post/How_to_determine_avg_domain_size_value_from_SEM_image_for_Thin_Foil
Thank you Alan F Rawle sir. I got that answers.
But till now there is confusion.
Mahindra Kothuri asked how to confirm whether his particles are in the nano range or not. I replied XRD can be a tool for this.
Is this correct or wrong?
Can you please explain?
Sukhendu Sadhukhan XRD looks at crystallite size not particle size. Thus, the crystallites could be in the nano range (< 100 nm). The particles may not be...
Measure the SSA of the system - this should be > 60m2/g for unity density if the average particle size is < 100 nm.
Thank you so much Alan F Rawle Sir.
Got it.
I found a pdf on SSA at
https://www.jocpr.com/articles/studies-on-the-density-and-surface-area-of-nanoparticles-from-camellia-sinensis-a-natural-source.pdf
Is there any more supporting paper references to this?
Sukhendu Sadhukhan Look at the (draft) EU definition for nanoparticles... For example, see attached.
Using XRD analysis, you can calculate the crystallite size.
For more information, you can read this article: Article Impact of Nd3+ Substitutions on the Structure and Magnetic P...
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