For the first time in the world, we succeeded in synthesizing the
room-temperature superconductor ($T_c \ge 400$ K, 127$^\circ$C) working at
ambient pressure with a modified lead-apatite (LK-99) structure. The
superconductivity of LK-99 is proved with the Critical temperature ($T_c$),
Zero-resistivity, Critical current ($I_c$), Critical magnetic field ($H_c$),
and the Meissner effect. The superconductivity of LK-99 originates from minute
structural distortion by a slight volume shrinkage (0.48 %), not by external
factors such as temperature and pressure. The shrinkage is caused by Cu$^{2+}$
substitution of Pb$^{2+}$(2) ions in the insulating network of Pb(2)-phosphate
and it generates the stress. It concurrently transfers to Pb(1) of the
cylindrical column resulting in distortion of the cylindrical column interface,
which creates superconducting quantum wells (SQWs) in the interface. The heat
capacity results indicated that the new model is suitable for explaining the
superconductivity of LK-99. The unique structure of LK-99 that allows the
minute distorted structure to be maintained in the interfaces is the most
important factor that LK-99 maintains and exhibits superconductivity at room
temperatures and ambient pressure.
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