Stabilization of carbon nanotubes by filling with inner tubes: An optical spectroscopy study on double-walled carbon nanotubes under hydrostatic pressure

TL;DR

This study demonstrates that filling carbon nanotubes with inner tubes enhances their mechanical stability under pressure, as shown by optical spectroscopy measurements of double-walled nanotubes compared to single-walled ones.

Contribution

The paper provides experimental evidence that inner tube filling stabilizes double-walled carbon nanotubes against pressure-induced deformation, confirming theoretical predictions.

Findings

Reduced optical transition redshifts in double-walled nanotubes under pressure

Enhanced mechanical stability due to inner tubes

Critical pressure for deformation aligns with theoretical models

Abstract

The stabilization of carbon nanotubes via the filling with inner tubes is demonstrated by probing the optical transitions in double-walled carbon nanotube bundles under hydrostatic pressure with optical spectroscopy. Double-walled carbon nanotube films were prepared from fullerene peapods and characterized by HRTEM and optical spectroscopy. In comparison to single-walled carbon nanotubes, the pressure-induced redshifts of the optical transitions in the outer tubes are significantly smaller below $\sim$10 GPa, demonstrating the enhanced mechanical stability due to the inner tube already at low pressures. Anomalies at the critical pressure P$_d$$\approx$12 GPa signal the onset of the pressure-induced deformation of the tubular cross-sections. The value of P$_d$ is in very good agreement with theoretical predictions of the pressure-induced structural transitions in double-walled carbon nanotube bundles with similar average diameters.