User talk:217.149.174.62

Is LK-99 doped or is lead apatite doped?
I think some of the wording in the https://arxiv.org/pdf/2308.00676.pdf paper is unintentional

Unintentional: "If Doped" implies that LK-99 needs to be doped.

"This puts Pb9Cu(PO4)6O in an ultra-correlated regime and suggests that, without doping, it is a Mott or charge transfer insulator. If doped such an electronic structure might support flat-band superconductivity or an correlation-enhanced electron-phonon mechanism, whereas a diamagnet without superconductivity appears to be rather at odds with our results."

Later they say:

"It would put such a doped Pb10−xCux(PO4)6O compound into the category of a doped Mott or charge transfer insulator. I"

Here they call LK-99 a "doped compound", not that they dope LK-99

"In Section S.I, we provide computational details and DFT structural relaxation results regrading the energetically favorable positions of extra O and doped Cu atoms. I"

More evidence that they do not mean doping LK-99, but doping PB10(PO4)6O to make LK-99

Here they compare Lead Apatite with LK-99 " To investigate the ground state crystal structure of both Pb10(PO4)6O and Pb9Cu(PO4)6O, we need to answer three questions totally: (1) Has the extra O a favorable position? (2) Are the extra O atoms in adjacent unit cells prone to occupy different, alternating positions? This is here simulated by supercell calculations. (3) Do the doped Cu atoms prone occupy different positions in a disordered or long-range pattern? "

It's the Cu that is doing the Doping. LK-99 requires Cu. LK-99 is not without Cu.

So if Cu is in LK-99, this asks, what is additioinally doped in Pb9Cu(PO4)6O?

Again, the definition of LK-99: A material called LK-99®, a modified-lead apatite crystal structure with the composition (Pb10-xCux(PO4)6O (0.9<x<1.1)), has been synthesized using the solid-state method. 75.172.56.50 (talk) 23:49, 2 August 2023 (UTC)


 * The above cited three points"(1)...(3)" are from the supplemental material when discussing where the O and Cu (in difference to Pb) may be located, and then doing DFT calculations with various possibilitie for Pb10(PO4)6O and Pb9Cu(PO4)6O.
 * In the Conclusion it is clearly said:
 * "It is a bit puzzling, why Pb9Cu(PO4)6O with such a
 * large U/W was not a Mott insulator or charge transfer
 * insulator in experiment. A possible explanation is hole
 * or electron doping."
 * Pb -> Cu or changing x in Pb10-xCux(PO4)6O is not electron or hole doping
 * because Cu and Pb are both 2+.
 * The conclusion continues:
 * "This puts O (or P) deficiency or excess as a possible source for such an accidental doping
 * off-stoichiometry. Given the synthesis procedure [9] also
 * the replacement of O or P by S is conceivable. Against
 * this background, it might be advisable to actively procure
 * such a doping in the synthesis process..."
 * Again that is not doping x but another doping changing the electron count.
 * Also he_abstract clearly states:
 * "This puts Pb9Cu(PO4)6O in an ultra-correlated regime and suggests that, without doping, it
 * is a Mott or charge transfer insulator. If doped such an electronic structure might support flat-band
 * superconductivity or an correlation-enhanced electron-phonon mechanism, whereas a diamagnet
 * without superconductivity appears to be rather at odds with our results."
 * I will change it back, it is almost word-by-word the essence from the abstract. 217.149.174.62 (talk) 04:23, 3 August 2023 (UTC)
 * I will change it back, it is almost word-by-word the essence from the abstract. 217.149.174.62 (talk) 04:23, 3 August 2023 (UTC)