thermal evaporation of our labortory is being used as an Al(aluminum) deposition.
but i want to deposit WO3(tungsten oxide) with this thermal evaporation instrument.
is not the vacuum chamber contaminated?
Al is a solid form and WO3 is a powder form
if i wrap the inner wall with foil, is not there a problem?
For a vapor of WO3 you need a high oxygen partial pressure (best is the pure O2). In vacuum at high temperatures, WO3 will split off oxygen and, ultimately, forms metallic tungsten. So evaporation of WO3 into a vacuum chamber is not possible.
When there is possibility of contamination I usually cover the inside of the chamber with Aluminum, using double sided adhesive. Make some pin-holes to the aluminum sheets, to avoid virtual leaks between Al foil and walls of the chamber.
thank you for your help.
as the result of my research,
in many papers, after thermal evaporation of WO3 in high vacuum,
the substrate that WO3 is deposited undergoes an annealing(O2 or ambient air) process at 600~700 degree .
than i saw i could obtain WO3 in papers.
Dear. Martin E. Baltazar-Lopez
thank you for your opinion. but i don't understand your mention
" Make some pin-holes to the aluminum sheets, to avoid virtual leaks between Al foil and walls of the chamber"
what's mean pin-holes?
and in your case is not it contaminated in chamber?
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