Absence of Superconductivity in LK-99 at Ambient Conditions

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid-State Chemistry

Background:

• Recent reports claimed superconductivity in modified lead apatite (LK-99) above room temperature.
• Numerous attempts to replicate these findings have yielded mixed results, necessitating further investigation.

Purpose of the Study:

• To synthesize phase-pure LK-99 using improved precursors and the established synthesis method.
• To experimentally verify the superconducting properties of LK-99 at room temperature.

Main Methods:

• Synthesis of LK-99 following Sukbae Lee et al.'s procedure with phase-purity confirmed by powder X-ray diffraction (PXRD) and Rietveld refinement.
• Electrical resistivity measurements from 215 K to 325 K.
• Magnetization measurements using a SQUID magnetometer.
• First-principles calculations of the electronic band structure.

Main Results:

• Synthesized LK-99 exhibited phase purity and a lead apatite structure.
• Resistivity measurements indicated highly resistive, insulator-like behavior between 215 K and 325 K.
• Magnetization data at 280 K resembled that of a resistive diamagnetic material.
• First-principles calculations revealed band crossing at the Fermi level, suggesting strong correlation effects.

Conclusions:

• The synthesized LK-99 (Pb9CuP6O25) does not exhibit superconductivity at room temperature.
• Experimental results contradict the claims of room-temperature superconductivity in LK-99.
• The material displays insulating characteristics and diamagnetic behavior consistent with its structure.