Dear Fellows,
I synthesize intermetallic nanoparticles by chemical reduction and disperse them on carbon support. The TEM equipment I use is unable to highly magnify above 40kx. Beyond that the whole focusing and alignment work is lost due to lower voltage (100 kV) and conventional LaB6 filament. I am attaching some micrograph examples.
I was wondering if it is OK to estimate the particle size distribution of
Hello, dear Ahmed.
I have seen a lot of publications where they make comparison of very small distribution particles at such low magnification. In my opinion, you could measure such small particles (or any distribution, at least 50-100 particles)
If you have any doubt, please contact me,
With kind regards,
Julián.
The first two pictures are rather good. The third one (taken at the same magnification) is not focused properly. I think your TEM is in workable condition and you should easily get magnifications x100k, if not higher. At 100kV even old TEM with LaB6 should be able to provide magnifications x300k with no problems. Actually quality and magnification of your pictures are good for the task. You problem is conglomeration of particles, not a TEM. You may want to try different solvents, sonication, or even surfactants... Not an easy task.
Julián E. Sánchez-Velandia
Thanks for your reply. I presume you have experience with the particle size distribution by means of ImageJ. If that is the case, I am wondering how exactly could I make sure the software is measuring the metal particles which appear darker to me? I have been using it for a long while now and everytime, I must guess and add constraints to get me close to what actually I see in the image. If I don't do that, I would get a million particles below 2 nm which may be attributed to the carbon porous structure or even the noise signals.
Vladimir Dusevich
Many thanks to you. I tend to agree with you that some agglomeration has happened in my sample. That is actually what I have been working on in my PhD and tried different synthesis methods using ethylene glycol and NaBH4.
However, I think the equipment could not achieve 100kx magnification. Even Dr. Svetomir Tzokov, the EM facility manager at Uni of Sheffield has told me going above 70kx with this equipment is not advisable.
Alaa A. A Aljabali
Thanks for your reply.
Unfortunately, I do not have HRTEM images, but I do have reasonable normal TEM ones. I plan to to provide more than one micrgraph with the article.
Ahmed Elsheikh , while I respectfully disagree with Dr. Svetomir Tzokov, I have to repeat: magnification of your pictures is good for your task, quality of pictures is good (just a bit of inaccuracy with focusing). You need nothing more from a TEM.
Dear Ahmed Elsheikh
I have carried out particle size distribution using ImageJ. In general, I have had accurate results according to literature with oxide particles (Fe and cu oxides particles). If you want, I could take your images and help to process using ImageJ and compared it with the results that you have obtained.
With kind regards, Julián.
Dear Julián E. Sánchez-Velandia
Your offer to try and calculate the particle size distribution is very kind and generous. It is useful so that I could double-check my self.
Could you please make use of the two images attached of Pd nanoparticles supported on carbon black (particle size 30-60 nm)?
Thank you,
Ahmed
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