I experienced no problems while imaging magnetite nano-crystal in TEM. The standar preparation method includes: (I) dispersion of particles in solution (preferrably absolute ethanol, DMF, water etc) (II) sonication of the particles to "break-down" the agglomeration and (III) dipping the mesh or dropping the solution onto the mesh (somehow depends on concentration, type of mesh and operator). No coatings were ever needed for TEM of magnetite. Most probably you'll see island of Pt if coated (of course depends on the desired magnifications...). If magnetite particles are small enough, you'll also have no problems with possible lift-off in the TEM due to large EM fields (depends on the volume of your particles).

Fe3O4 is magnetic and the particles will stick together - how can you demagnetize this effectively? The forces operate over a long distance.  I think if you take it above the Curie temperature and cool, it will still be magnetic. Small particles also interact and attract via van der Waals forces. You'll have micrographs of fused aggregates not individual separate particles, in my opinion.  I hope and trust that someone else has better ideas.

Hi peter

If you have any problem with carbon coated grid technique , you can use the Epoxy sample preparation technique for nano particle, which can provide better result in your case. If you want any further detail procedure for Epoxy TEM  sample preparation technique you are always well come. 

I am attaching one link, which related to your field.

https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=11&cad=rja&uact=8&ved=0ahUKEwjCrf3c0d_OAhVFOo8KHcmeARAQFghWMAo&url=http%3A%2F%2Fwww.cjche.com.cn%2FEN%2Farticle%2FdownloadArticleFile.do%3FattachType%3DPDF%26id%3D1301&usg=AFQjCNGUjen_wewAhOaA3ShDOfME5q3IIw&sig2=C8QAHbwa5JMqzCXeAzhiPg

thanks

Deepak Kumar

I am SEM user and as well as working on nanomaterials. In my opinion, just coat these samples with gold or palladium instead of carbon. I am pretty sure, it will work.

Regards

Rehan PhD 

if you coat nanoparticles with polymer, biopolymer or any capping agent you can get good images. If you dont coat then you can try to sonicate nanopoarticles in ethanol 

Thank you so much. After I put the particles on the copper mesh, I would coat the mesh with platinum. Is it suitable? Ok, I would sonicate the particles at next time:)

I experienced no problems while imaging magnetite nano-crystal in TEM. The standar preparation method includes: (I) dispersion of particles in solution (preferrably absolute ethanol, DMF, water etc) (II) sonication of the particles to "break-down" the agglomeration and (III) dipping the mesh or dropping the solution onto the mesh (somehow depends on concentration, type of mesh and operator). No coatings were ever needed for TEM of magnetite. Most probably you'll see island of Pt if coated (of course depends on the desired magnifications...). If magnetite particles are small enough, you'll also have no problems with possible lift-off in the TEM due to large EM fields (depends on the volume of your particles).

Thank you Janez Zavašnik

Thanks for your reply and information :)

It's helpful!

Fully agree with method suggested by Dr. Janez. I have used the same simple methodology described by Dr. Janez Zavasnik, using the sonication method in ethanol, and never faced any problems while handling NiFe2O3 nano particles.

K. Sreenivas

Some of the methods are pertinent. It depends on the size. capping may result in unagglomertated particles. No need to coat with Pt/ Gold. After sonication in appropriate solvent, the drop containing the NPs can be poured on the grid from a distance and then it can be tilted a bit. We have observed 8-14 nm Fe3O4 NPs. You may find this useful 

Journal of Magnetism and Magnetic Materials 414 · April 2016

DOI: 10.1016/j.jmmm.2016.04.069