Abstract
Experimental evidence investigating the high-pressure response (0–9 GPa) of aligned single-walled carbon nanotube (SWNT) arrays in the extreme low Raman shift region (10–100 , squash mode region) is provided to verify a predictive model for deformation-related phase transitions. In addition to the well-known radial breathing mode (RBM) and despite the technical challenges associated with the detection of Raman signals very close to the exciting laser frequency, clear SWNT squash mode peaks were identified and used to refine the predictive model. Furthermore, this paper investigates and proposes explanations for the detailed behavior of the pressure dependent cross-sectional transition. The results demonstrate experimentally, and confirm earlier theoretical models, that the critical pressure scales against the chirality dependent nanotube diameter . Finally, the pressure and chirality dependent Raman upshifts of the squash mode, characterizing the phase transition, are found to be larger than those of the RBM, respectively, confirming the general theoretical prediction of greater environmental sensitivity of squash modes.
- Received 22 November 2016
- Revised 22 April 2017
DOI:https://doi.org/10.1103/PhysRevB.95.205434
©2017 American Physical Society