In "First-principles study on the electronic structure of Pb₁₀₋ₓCuₓ(PO₄)₆O (x=0, 1)"[^0] the authors explore the question of whether lead apatite combined with various dopants, like Ni, Cu, Zn, Ag, and Au, can exhibit desirable electrical properties such as superconductivity. They show that Au, Ag, and Cu have similar effects on the Fermi-level band gap, and that this appears critical to the interesting electrical properties described by The First Room-Temperature Ambient-Pressure Superconductor"[^1] and "Superconductor Pb₁₀₋ₓCuₓ(PO₄)₆O showing levitation at room temperature and atmospheric pressure and mechanism"[^2].
Their paper notes that Ag exhibits notably different apparent electrical properties than Au and Cu in this combination, despite also being one of the "noble metals". However, due to the economic interest in finding alternatives to gold, it is reasonable to expect people will examine them. Many papers explore the effects of silver doping on high-temperature superconductivity, and some such as "Possible High Tc Superconductivity in Ag Doped PbO(1+δ) (0.4 < δ < 0.6)"[^3] examine specifically silver-doped lead-oxide, though none have yet discovered a room-temperature superconductor.
The question is: Will a silver-doped lead-oxide composition of some variety be proven to be a room-temperature ambient-pressure practical superconductor of some classification by 2027?
A note on definitions:
"room temperature" (above 0C)
"ambient pressure" (below 1 megapascal, i.e. less than 10 atmospheres)
"practical superconductor" means that it may deviate from the classical definition of a superconductor if it still exhibits the zero-resistance property over a 5cm wire or matrix, even if it e.g. does not have a classical expression of the Meißner–Ochsenfeld effect or flux pinning
"lead-oxide": lead-apatite would qualify, as would something based on e.g. lead sulfate (PbSO₄).
[^0]: https://arxiv.org/abs/2307.16040
[^1]: https://arxiv.org/abs/2307.12008