title: A new lower limit for the ultimate breaking strain of carbon nanotubes.
abstract: We apply immense strain to ultralong, suspended, single-walled carbon nanotubes while monitoring their Raman spectra. We can achieve strains up to 13.7 ± 0.3% without slippage, breakage, or defect formation based on the observation of reversible change in Raman spectra. This is more than twice that of previous observations. The rate of G band downshift with strain is found to span a wide range from -6.2 to -23.6 cm(-1)/% strain. Under these immense strains, the G band is observed to downshift by up to 157 cm(-1) (from 1592 to 1435 cm(-1)). Interestingly, under these significant lattice distortions, we observe no detectable D band Raman intensity. Also, we do not observe any broadening of the G band line width until a threshold downshift of Δω(G) > 75 cm(-1) is achieved at high strains, beyond which the fwhm of the G band increases sharply and reversibly. On the basis of a theoretical nonlinear stress-strain response, we estimate the maximum applied stress of the nanotubes in this study to be 99 GPa with a strength-to-weight ratio of almost 74,000 kN x m/kg, which is 30 times that of Kevlar and 117 times that of steel.
authors.affiliation: Department of Physics, University of Southern California, Los Angeles, California 90089, USA.
authors.forename: Chia-Chi
authors.initials: CC
authors.lastname: Chang
authors.forename: I-Kai
authors.initials: IK
authors.lastname: Hsu
authors.forename: Mehmet
authors.initials: M
authors.lastname: Aykol
authors.forename: Wei-Hsuan
authors.initials: WH
authors.lastname: Hung
authors.forename: Chun-Chung
authors.initials: CC
authors.lastname: Chen
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Cronin