Conductive Mounting Media

[Probeman]

I'm wondering if anyone has come across a new and improved material for mounting samples that is more insensitive to the beam than regular epoxy.  Electrical conductivity would be nice, but not essential.

I'm imagining that the material would be like an epoxy, but would not vaporize at least under relatively mild beam conditions of a few tens of nano-amps or so.

Anything come to mind?

[aburnham]

Not suitable for routine work, but when we do SIMS analyses we either press pre-polished grains into indium or mount grains in the eutectic Sn-Bi alloy and polish down into that. The latter is tricky because you need to find a way of stopping your grains from moving when you pour hot molten metal onto them, but it does allow you to polish (unlike indium) and gives an exceptionally clean (H-free) surface.

[Probeman]

Not suitable for routine work, but when we do SIMS analyses we either press pre-polished grains into indium or mount grains in the eutectic Sn-Bi alloy and polish down into that. The latter is tricky because you need to find a way of stopping your grains from moving when you pour hot molten metal onto them, but it does allow you to polish (unlike indium) and gives an exceptionally clean (H-free) surface.

Yes, I've heard of these techniques, but let me ask: at what temperature is the Sn-Bi alloy when you pour it on your specimen grains?

And secondly, how well does it hold small grains for polishing?  How small is too small?

Finally does one get "smearing" of the Sb-Bi onto the mineral or glass grain surfaces during polishing?

I'd like to model this Sn-Bi composition for secondary fluorescence effects, even though one isn't usually analyzing for Sn or Bi in minerals or glasses...  do you have a composition for this alloy?
john