Metal powders can be harmful to filament and can cause malfunctions if put directly on chamber. What solutions can you offer me to examine them? Thank you in advance.
Can you bring the powder into epoxy resin? If, yes (we do it this way) you can process a plane surface by polishing and use the SEM without danger.
U can disperse the powder in acetone or isopropyl alcohol and deposit directly on carbon type wait till acetone evaporate then blow a compressed air so that free particles goes off and rest will stick to carbon tape.
Epoxy resin is an insulator and in spite of metallic powders attach it some electric conductivity it may not be enough to obtain good SEM images. Also there is a deagglomeration problem to be resolved before mixing particles with epoxy. Better way may be dispersing the powders in some fluid like alcohol on a glass substrate, sputter carbon on them after drying and detach the film.
Thanks alot for answers. Sergei i will try to do it with the way you suggest. As you said agglomeration can be a problem.
Thanks for help Volker i will ask for help from a friend who knows German.
You can disperse the powder in acetone or alcohol and put a drop or two on an aluminium stub. Let the liquid evaporate then blow some compressed air so that free particles go off then you can examine the sticking powder on the aluminium stub in the SEM. You can also sprinkle some particles on the stub and put a drop or two of the above mentioned liquids and let the liquid evaporate. Carbon tape can also be used. This can also be done on a glass substrate or molding in a polymers resin as some of the researchers have already mentioned it will reduce the chances of chamber contamination but then you need to sputter some conducting material onto those particles and make sure that a proper electrical connection is there. For examination of microstructure molding in a polymer resin can be useful but for morphology of the powder other methods mentioned above are useful.
Yusuf, dispersion in a small conductive disc, cilinder, conductive tape, could be options, and there are some conductve resines with graphite or metals based.
You could also try to apply very thin layer of silver paste on a aluminium slab and then attach/stick your metal particles on it. They are usually curable at room temperature and has high adhesion to any material. Wait till it is dry, blow with compressed air and put it in the chamber.
Layer of silver paste will coat the powder as well. It is difficult to do and depends on the size and nature of the particles.
You can deposit the metal powder directly on a self stick carbon tape. If you notice charging in the secondary electron image because of poor electrical contact, you can switch to BSE(Backscattered Electron) mode. There is actually no need to suspend these metal particles in any solvent prior to depositing them on the carbon tape.
We usually do powder slurry with acetone (alcohol or glycerol), a slurry is formed by shaking in an ultrasonic bath. A couple of drops of the resulting suspension dripped onto a glass slide with a prepared track of the carbon tape. After evaporation of the liquid on the glass remains dispersed powder. Powders anchoring sputtering a thin layer of Au (2-5 nm). This results in great shots without harm to the device.
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