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This is probably not the best place to post this, but I'm posting in case it might reach the right people who could give this a try.

The current synthesis for the proposed LK-99 superconductor is a multi-step process that goes through a sulfate compound, while the end product is a phosphate compound [1, 2]:

$\ce{PbO + Pb(SO4) -> Pb2(SO4)O}$
$\ce{3 Cu + P -> Cu3P}$
$\ce{Pb2(SO4)O + Cu3P -> Pb_{10-x}Cu_x(PO4)6O + S(g)}$, where $(0.9 < x < 1.1)$

It may produce several byproducts when the equation is balanced:

$\ce{5 Pb2SO4O + 6 Cu3P → Pb9Cu(PO4)6O + 5 Cu2S + Pb + 7 Cu}$

Since the current synthesis is already based on $\ce{PbO}$, I propose the following alternative route:

$\ce{9 PbO + CuO + 6 H3PO4 -> Pb9Cu(PO4)6O + 9 H2O(g)}$

Single pot, anywhere above $\ce{100C}$, to let the water evaporate. Since there were some suggestions that it needs some extra doping with oxygen or sulfur [3], then probably do this is in an open flask, or mix in a bit of sulfur in there.

This is a simple acid-base reaction, which might even occur in the solid phase. Or maybe it can be done in $\ce{H3PO4(aq)}$, letting the product precipitate. Then dry it in a vacuum furnace.

What are some possible complications with this reaction?

  1. https://en.wikipedia.org/wiki/LK-99#Synthesis
  2. https://arxiv.org/abs/2307.12008
  3. https://arxiv.org/abs/2308.00676
MichaelK
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  • Not working at all would be pretty big complication ;) See, you can't just add reagents and hope it's gonna work like you want. Also this whole "LK-99" thing is highly dubious - there's likely no superconductor like that to be made, at least not some magically room temp. stuff. – Mithoron Aug 07 '23 at 21:42
  • There's plenty of reason to expect that it won't be superconducting, or won't even have the right crystallographic structure. But, is there a reason to expect that it won't give the expected compound (chemical formula)? Or that there won't be a reaction at all? This is a simple acid-base ion exchange. But I was asking more towards e.g. it reacting too violently (or not at all, as you suggest), or giving off toxic fumes, etc. – MichaelK Aug 08 '23 at 15:52
  • Well, if acid was conc. enough, it should dissolve it, but products would be different. I don't see an option for mixed oxide, just some mixture of (hydrogen)phosphates. – Mithoron Aug 08 '23 at 17:41
  • The target material is an apatite, so it is a phosphate material. The source oxides are both amphoteric AFAIK, so should dissolve in mineral acids. But whether or not phosphoric acid is strong enough, I don't know. A less direct route is to dissolve the oxides in HCl and react with sodium phosphate. – MichaelK Aug 08 '23 at 19:15
  • (Though lead chloride is only mildly soluble.) – MichaelK Aug 08 '23 at 19:28
  • My original thoughts were to react with anhydrous $\ce{H3PO4}$. Either in the solid phase and dry the product later, or if done above $\ce{100C}$ to let the water evaporate, then the phosphoric acid would melt, and it becomes a mixed phase reaction. Mixed oxide powder with liquid phosphoric acid. – MichaelK Aug 08 '23 at 19:36

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