BASF
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P2O5 by pyrolysis
according to the following patent, aluminum metaphosphate can be decomposed at 950-1100°C:
Al3(PO3)3 >AlPO4 + P2O5
patent on process for semi-conductor-donation, view page 4
It is clear that they wanted a very controllable amount of P on their silicon-wavers, i suppose there should exist (meta)phosphates which can be
decomposed more easily !
Any proposals?
HLR
[Edited on 6-5-2003 by BASF]
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madscientist
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On a related note, here's an idea that occurred to me a few months back:
4Cu<sub>3</sub>(PO<sub>4</sub> <sub>2</sub>
----> 4Cu<sub>3</sub>PO<sub>4</sub> + P<sub>4</sub>O<sub>10</sub> + 3O<sub>2</sub>
The cupric phosphate would be cheap and easy to prepare OTC - simply mix solutions of cupric sulfate and sodium phosphate, then filter out the cupric
phosphate (which would precipitate).
I weep at the sight of flaming acetic anhydride.
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BASF
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Hmm, from my point of view it seems possible what you proposed.....
Why copper? i always wondered wether heavy metals can be decomposed more easily due to the less ionic character of the molecule, i suppose.
So on this basis:
Na3PO4>Ca3(PO4)2>FePO4>Cu3(PO4)2>Zn3(PO4)2>Pb3(PO4)2 ?
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4Cu3(PO4)2 ----> 4Cu3PO4 + P4O10 + 3O2
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It is obvious from the above formula that a reductant such as carbon would help the reaction.
On the other hand, the purity will definitely be better, if no carbon is added.
Aluminum powder seems to be a compromise, but it is costly....
I should do some further search on flake-aluminum....
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