Superconducting fullerene nanowhiskers.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Fullerene-based materials exhibit interesting electronic properties, including superconductivity.
• Potassium-doped fullerene crystals (KxC60) are known superconductors, but their performance in nanowhisker form is less explored.

Purpose of the Study:

• To synthesize and characterize superconducting fullerene nanowhiskers (C60NWs) via potassium (K) intercalation.
• To investigate the impact of potassium content (x) on the superconducting properties and lattice structure of KxC60NWs.
• To compare the superconductivity of KxC60NWs with that of KxC60 crystals.

Main Methods:

• Synthesis of K-doped C60 nanowhiskers (Kx C60NWs) using potassium intercalation.
• Measurement of superconducting properties, including superconducting transition temperature (Tc) and superconducting volume fraction (shielding fraction).
• X-ray diffraction (XRD) analysis to determine lattice structures.

Main Results:

• Synthesized Kx C60NWs exhibited large superconducting volume fractions, reaching up to 80%.
• The superconducting transition temperature (17 K) was independent of K content (x) in Kx C60NWs (1.6 ≤ x ≤ 6.0), while volume fractions varied with x.
• The highest shielding fraction was observed in K(3.3)C60NW after heating at 200 °C, significantly outperforming K-doped fullerene crystals (<1% shielding).
• Kx C60 crystals showed superconductivity at 19 K for K3C60.

Conclusions:

• Potassium-intercalated fullerene nanowhiskers (Kx C60NWs) demonstrate significantly enhanced superconducting volume fractions compared to their crystalline counterparts.
• The superconducting transition temperature of Kx C60NWs is robust against variations in potassium content within the studied range.
• These findings highlight the potential of fullerene nanowhiskers as a promising platform for high-performance superconducting materials.