Specific heat anomaly in large-diameter multiwall carbon nanotubes

GUILLERMO A. JORGE; V. BEKERIS; M. M. ESCOBAR; S. GOYANES; D. ZILLI; A. L. CUKIERMAN; R. J. CANDAL

Buenos Aires

Workshop; At the Frontiers of Condensed Matter IV; 2008

CNEA

We present micro-calorimetric specific heat measurements on different multiwall carbon nanotubes of large outer diameter,  as a function of temperature in the range 10-120 K. A clear  anomaly at 60 K with  the shape of a peak is present, and both the height and the characteristic temperature are independent of magnetic field and do not exhibit thermal hysteresis. These features suggest that the anomaly may be  caused by a structural change. The anomaly is also unaffected by induced intertube disorder. We associate this anomaly with a melting of orientational dislocations of individual tubes within a multiwall nanotube, an effect that was theoretically predicted to occur in carbon nanotubes but never observed experimentally.