Naslov
Low-energy vibrational excitations in carbon nanotubes studied by heat capacity

Autori
Lasjaunias, Jean Claude ; Biljaković, Katica ; Monceau, Pierre ; Sauvajol, Jean Louis

Izvornik
Nanotechnology (0957-4484) 14 (2003); 998-1003

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Thermal properties; nanotubes; phonons or vibrational states; disordered systems

Sažetak
We present low temperature heat capacity measurements performed on two different kinds of single-walled carbon nanotube (SWNT) bundles, which essentially differ by their mean number of tubes (NT ) per bundle. For temperatures below a few Kelvin, the vibrational heat capacity can be analysed as the sum of two contributions. The first one is a regular T3 phononic one, characteristic of the 3 dimensional (3D) elastic character of the bundle for long wavelength phonons. A crossover to a lower effective dimensionality appears at a few Kelvin. From the 3D contribution, we estimate a mean sound velocity, and hence a mean shear modulus of the bundle. The difference in amplitude of the acoustic term and in the crossover temperature between the two samples is ascribed to the different bundle topology (i.e. NT ). The second contribution, of similar amplitude in both kinds of samples, shows a peculiar power law T*alpha variation (alpha<1) indicative of localized excitations and it is very probably due to intrinsic structural defects of the nanotubes.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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