From my point of view the best method of mounting nanoparticles for SEM is to drop-cast well water –diluted solution of particles on pre cleaned surface of plastic or glass substrate (plastic is better if BSE will be used). During drying, forces of water surface tension will press particles hard enough to create good bond with substrate due to Van Der Waals force. While using carbon sticky tape can produce some good results for bigger agglomerates of particles, really small ones will be semi submerged in adhesive of the tape.

Iron borides should be conductive enough to observe without any coating. It is a blessing. Coating of nanoparticles can distort their shape greatly. If, for example, you coat 10 nm particles with layer of metal with thickness of 10 nm, resulting particles will be 30 nm… Carbon coating will be even thicker. Anyway, using Au for high resolution coating is not recommended; Pt and Au-Pd are better; even better could be Os, but it needs special coaters.

Finally, I see no trouble with magnetic properties nanoparticles; it should not cause any trouble.

Hi Pawel, I think the easiest way is to take a piece of double sided carbon tape and put that on your SEM sample holder. Then you can apply your powder on top of the tape and since you can blow off any excess powder, I guess you shouldn't have any contamination problems. Good luck!

Hi Pawel, the recipe suggested by Wouter seems to be perfect. You can also apply a thin layer of carbon by sputering on the top of your sample before analysis in order to avoid any contamination.

Hi Pawl, Wouter told you the easiest way to prepare the powder sample for SEM characterization.

You can stick the nanoparticles directly onto a carbon tape and press it lightly or before this you can give one drop of acetone to the carbon tape than add your particles and then blow with strong air. Such prepared NPs are firmly to the SEM holder - there is no fear of contamination.

The method proposed by wouther is perfect. the easiest way is to put the powder on a carbon adhesive double sided in order to avoid any contamination.

.. I am just curious: if the particles are really nanosize, what kind of information do you think you can obtain with SEM? You probably need a FESEM and also in that case you can just see the morphology

Gold platting ?

Previous suggestions are all good. When you try the SEM, the SEM image will be distorted due to the electron-magnetic field effect. Try to look the images as a function of applied beam voltage. You will have experienced in the SEM stage.

U need to first press the powder on an adhesive carbon tab so that its attached to the SEM holder and then u need to sputter coat it with gold to avoid charging !

thank everyone for valuable help, of course I meant FESEM technique not SEM,

You can make a pallet by high pressure using palletiser . Than you can fix it with SEM holder by any conducting adhesive. Make gold sputter on the your sample as described by GAURAV LALWANI

I'd give the same advice as many above, gold sputter. We analyze magnetic materials often and SEM really hasn't had much problem aside from charging...which the gold alleviates.

From my point of view the best method of mounting nanoparticles for SEM is to drop-cast well water –diluted solution of particles on pre cleaned surface of plastic or glass substrate (plastic is better if BSE will be used). During drying, forces of water surface tension will press particles hard enough to create good bond with substrate due to Van Der Waals force. While using carbon sticky tape can produce some good results for bigger agglomerates of particles, really small ones will be semi submerged in adhesive of the tape.

Iron borides should be conductive enough to observe without any coating. It is a blessing. Coating of nanoparticles can distort their shape greatly. If, for example, you coat 10 nm particles with layer of metal with thickness of 10 nm, resulting particles will be 30 nm… Carbon coating will be even thicker. Anyway, using Au for high resolution coating is not recommended; Pt and Au-Pd are better; even better could be Os, but it needs special coaters.

Finally, I see no trouble with magnetic properties nanoparticles; it should not cause any trouble.

Sorry, I forgot to mention that substrate should be pre coated with conductive coating.

I've had success looking at magnetic materials in FE-SEM by first heating past the Curie temperature so that the beam can image the sample surface.

To Matt: thank you for the tip! I am also having a problem taking FESEM for magnetic nanoparticles. The operator told us that he cannot take SEM images for magnetic nanoparticles. Looks like I need to heat up my samples past the Tc then.

Some of the RG members have already told about the Gold sputtering. I also agree with them. This could help you to take FESEM image of your sample.

What is the logic behind heating above curie temperature? Is it like the particles lose their magnetic property at this critical temperature?

To heat the sample above the curie temperature is required because if not then magnetic materials generally transition metals which can also give its contribution to the image.

I have two propositions:

1. If the particles are really small then You can use technique proposed by Vladimir but not on bulk substrate. You can use copper grid with carbon film, that one which is used for TEM to observe powder samples. Then if You have STEM mode in Your SEM You can use both SE and STEM images. Without background from substrate You should get nice images. If particles are really small, and You would avoid very close WD, then there is small interaction between magnetic field and small volume of the magnetic material.

2. !!! Never use carbon sticker for magnetic sample and out lens systems !!! Carbon cement is much better. You can put powder on cement, wait a bit to dry it and use strong magnet to remove all free particles. Then You are most safe for the microscope.

For in lens or electrostatic system there is no danger to make contamination by magnetic powders.

SEM/FIB sample chamber contamination can be easily removed by in-situ plasma cleaner, such as the EM-KLEEN plasma cleaner from PIE Scientific. It breaks down the oxygen or hydrogen molecules in air or other gas mixers that contains oxygen or hydrogen. Then the radical oxygen or hydrogen can diffuse into the SEM chamber and react with high molecular weight hydrocarbon contaminations on the chamber wall. The byproducts are usually low molecule weight high vapor pressure molecules, such as CO2, that can be easily pumped out of the sample chamber. The attached photos show the comparison before and after sample & chamber has been cleaned by EM-KLEEN plasma cleaners.

http://www.piescientific.com/Product_Remote_Plasma_Cleaner