arXiv:2307.12037cond-mat.supr-con
Superconductor Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O showing levitation at room temperature and atmospheric pressure and mechanism
Abstract
A material called LK-99, a modified-lead apatite crystal structure with the composition Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O ($0.9<x<1.1$), has been synthesized using the solid-state method. The material exhibits the Ohmic metal characteristic of Pb(6s1) above its superconducting critical temperature, $T_c$, and the levitation phenomenon as Meissner effect of a superconductor at room temperature and atmospheric pressure below $T_c$. A LK-99 sample shows $T_c$ above 126.85$^\circ$C (400 K). We analyze that the possibility of room-temperature superconductivity in this material is attributed to two factors: the first being the volume contraction resulting from an insulator-metal transition achieved by substituting Pb with Cu, and the second being on-site repulsive Coulomb interaction enhanced by the structural deformation in the one-dimensional(D) chain (Cu$^{2+}$-O$_{1/2}$-Cu$^{2+}$ along the c-axis) structure owing to superconducting condensation at $T_c$. The mechanism of the room-temperature $T_c$ is discussed by 1-D BR-BCS theory.
They measured the resistivity of a pure Cu2S sample, a sample S1 containing 95% LK-99 and 5% Cu, and a sample S2 containing 30% LK-99 and 70% Cu2S. The resistivity of the Cu2S sample has a drop of 3 to 4 orders of magnitude at about 390K (when temperature decreases). In the S2…
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