Can anybody share some experience on how high should be the vacuum level to prevent growth of oxide layer at 300°C? I am interested in Pd, but would be grateful for information about other metals, e.g. Cu, as well as about Si.
Formulated in another way, would 0.1 mbar be enough?
0.1 mbar is about 7.5E-2 Torr; as such my personal opinion is that this is at least an order of magnitude too high. Usually you need a system with a turbo pump that reaches 1E-5 to 1E-6 Torr or better.
1) Even at 1E-6 Torr you still have enough residual oxygen (and CO+water, that's actually the bigger problem) in the chamber to sustainably poison a catalytic surface.
2) 300°C might be enough to bake off O2 from Pd but CO will remain to some extent, see Article CO adsorption on supported Pd catalysts studied by adsorptio...
If CO doesn't bother you, you will be fine for that surface, otherwise you need better vacuum.
3) Si will definitely get oxidized over time. Maintaining a fully clean Si surface over a long period is quite the challenge.
Thanks for your answers! The thing is, i would like to perform a set of experiemnts where Joule heating of thin PdSi films will occur, so i thought i can put the setup in a cheap "non-scientific" vacuum chamber ($100-$200) to prevent surface oxidation.
Then maybe the better way to go about it would be to do this in an inert gas atmosphere, like Argon or Neon ?
Ion, thank you, you are right! So i need a simple chamber and then just let Ar flow through it and oxidation shoud be prevented.
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