I want to decompose Al2O3 powder into O2 and Aluminum. The purity is 99.9% and it's in powder form. I know that the melting point of the aluminum oxide is over 2000 0C. But I love to know if there is any possible partial decomposition of Al2O3 which releases oxygen at a temperature below 1100 0C (Pressure below 1 Torr)?
It is practically impossible to thermally decompose of Al2O3, regardless of the temperature and oxygen partial pressure. If you look at the Ellingham diagram, you will understand that the theoretically necessary partial pressure of oxygen at 1100°C must be less than 10-30 bar (
Vadim Verlotski Thank you very much for your answer and I agree with you. I had the same thought but I've seen one research group had use Al2O3 to feed oxygen to limit nucleation density during graphene growth. When I read that paper, I had the same thought as you and I was wondering how did they able to decompose it or somehow managed to get oxygen out of Al2O3. That was the motivation for this question. I thought it would be possible to partially decompose Al2O3 based on that article and wanted to clarify it. Thank you very much for your answer and I want to specially thankful to you for providing Ellingham diagram. I was looking for such a detailed diagram.
It is not exactly my field of competence, but if I remember well Al/axOy core/shell nanoparticjes or Janus-like AlxOy nanoparticles (at very small size, in the 2-5 nm range) have a sensibly lower melting point possibly due to the dominant gamma-form of Al oxide (better to say sub-oxides). Therefere, if you are able to prepare (or obtain from someone else) such NPs you could possibly use the same as a source of O at temperatures even much lower than the melting point of bulk alpha-Al2O2
Giuseppe Curro and Liviu Popa-Simil
Thank you very much for your interesting answers.
Sajith Withanage
Al2O3 is a stable oxide, in theory. And a very difficult (very stable) oxide to decompose in practice. You will not like how this goes from here, in powder form it is stubbornly stable! I say this from the experience of it. But but if you're still up for it - there are workarounds (for Al powder with oxide layers ... not pure Al2O3)...
Perhaps the most useful workarounds resources I ever came across are papers that came from the University of Queensland, i.e. Graham Schaffer and team. They offer possible mechanisms of the oxide breakdown (layers on Al powder), the formation of intermediate spinels, and the necessary conditions and getters etc... check their work out and update the discussion with more correct for the interested.
Lookup some electrolytic methods as well, the patents are insightful.
I do wish you luck.
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