Please suggest some good solvents for dissolving completely the magnetic nanomaterials or powders as during TEM analysis or SEM analysis or for spin coating I have to dissolve my magnetic nanomaterial in liquid solvents (like ethanol or DI) but in TEM viewing it shows agglomeration and not very good images obtained for size determination and I think the reason is improper solubility of magnetic nanostructures in these solvents If it is the reason so please suggest some good solvents.
I am attaching TEM image of my magnetic nanocrystals
First of all, this is not a dissolution but a dispersion. Ethanol works well for preparing samples for TEM, including for magnetic NPS like yours, but you need to use ulrasonication of the suspension for 5 min at least. Then just take one drop of the suspension and deposit it on a copper TEM grid covered by a carbon membrane. The result should be much better. It is also possible that your suspension needs some dilution before ultrasonication.
Alain
First of all, this is not a dissolution but a dispersion. Ethanol works well for preparing samples for TEM, including for magnetic NPS like yours, but you need to use ulrasonication of the suspension for 5 min at least. Then just take one drop of the suspension and deposit it on a copper TEM grid covered by a carbon membrane. The result should be much better. It is also possible that your suspension needs some dilution before ultrasonication.
Alain
I do ultrasonicate my suspension for at least 15 mins but still it doesn't work...
Some of your particles are rather "big" (the biggest measures at least 100nm), so it is possible that they are permanently magnetized and not superparamagnetic as you might expect. Therefore, whatever you do, they remain sticked with each other by magnetic interaction ? In other words, what you observe is really representative of your sample, and this is an important information as such: your particles are agglomerated, and only some changes in the preparation method will give you smaller and possibly inividualized nanoparticles.
Alain
Never mix two words - dissolving and dispersion. As far as I could find from the answers above, you need the dispersion. Here I cannot add anything. Dissolving may be necessary to make the qualitative and, what is more important, quantitative analysis of the samples obtained.
So everyone has already mentioned sonication however, particle concentration in dispersion media plays a large role as to whether or not you see aggregates. Sometimes you are better off searching the grid of a very "dilute" sample rather then dumping in enough materials to make it them easy to find.
Have you tried PVP as a dispersing agent? PVP is very useful for dispersing ferrous particles. Use PVP as a capping agent while synthensizing nano material
I would suggest to look at this issue earlier - during synthesis. It is possible that you don't have nanoparticles but some dendrite microcrystals. Ultrasounds may help to break them into smaller pieces but probably not into individual particles.
Magnetic oxide particles can not be dissolved. I think you mean well dispersed. First ensure that the particles are properly coated. If not then magneto-static attraction will form aggregates. If coated particles are aggregated then you have to first dissociate these. This can be done by adding either alkali like NH4OH) or acid (mild HCl or nitric acid). Make the sample very dilute and this diluted sample may be further subjected to ultrasound. Then you follow standard TEM technique for sample preparation. even the if you find lump like one you have given ,it means that your particles are too large and you need further reduction in size.
to add, sonication may be very different in intensity. Suggested sonication meant using a sonotrode not an ultrasonic bath.
As already mentioned, sonication can only work for dispersion if particle interactions (including magnetic) are repulsive. Otherwise you will agglomerate them.
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