Anomaly of X-ray Diffraction Profile in Single-Walled Carbon Nanotubes

Abstract

X-ray diffraction (XRD) studies on single-walled carbon nanotube (SWNT) samples prepared by the arc-discharge method were reported. The XRD profile was basically explained to be a result of triangular packing of SWNTs with a lattice constant of 17.1 Å and an average nanotube radius of 7.1 Å. We found an anomalous change in XRD profiles before and after heat-treatment of the SWNT samples in air at ∼350°C. Combined with gravimetric measurements and resistivity measurements, a detailed simulation of the XRD profiles showed that air (oxygen, and/or nitrogen and/or water) can be condensed inside the SWNTs.

Diameter-dependent hydrophobicity in carbon nanotubes

“…[26][27][28][29][36][37][38] Based on this prior work, it is highly likely that the SWCNTs are completely empty at 324 K, are filled with water between RT and approximately 220 K, and are partially emptied below 220 K due to the WDT. The incomplete emptying of the SWCNTs below 220 K is attributed to the slow dynamics of water at low temperatures (see Fig.…”

“…The finite thickness of the bundle is assumed to broaden each Bragg peak, as described by the peak functions. Although this analysis has been widely applied in previous works, [26][27][28]31,[35][36][37][38] it does not provide information regarding all possible water adsorption sites, such as on the bundle surfaces. Therefore, as an alternative approach, we also used the Debye formula below to calculate the XRD patterns, 32,39,40 …”

“…26 The reasons of the reduction in the 10 peak intensity have been investigated by several methods, including neutron diffraction analyses 29 of D 2 O-and H 2 O-SWCNT systems and detailed XRD analyses 37 employing Rietveld and maximum entropy methods. [26][27][28][29]31,[36][37][38] It has been determined that the 10 peak is diminished when water is adsorbed inside the SWCNTs as a result of the subtractive superposition of the X-rays (or neutron beams) diffracted from carbon atoms in the SWCNTs and from water molecules inside the SWCNTs. 36 Conversely, water molecules adsorbed at interstitial channel (IC) sites surrounded by three neighboring SWCNTs tend to increase the 10 intensity, owing to the additive superposition of the diffracted X-rays at the 10 peak position.…”

Rietveld Analysis and Maximum Entropy Method of Powder Diffraction for Bundles of Single-Walled Carbon Nanotubes

“…(A.11), (A.12), and (A.13)], and φ(Q − |G K |) is the normalized profile function, which is further modified to an asymmetric form. 16,20 The use the wave vector Q = |Q| instead of scattering angle 2θ is the previous convention, 5,7,8 where the Lorentz factor becomes L(Q) = 1/ sin 2 θ or ∝ 1/Q 2 . By further taking the average of Eq.…”

Theoretical Studies on Formation, Property Tuning and Adsorption of Graphene Segments

“…Water encapsulated within hydrophobic SWCNTs, commonly known as ice nanotubes (INT), provide important clues to the functionality of biological nanopores (Sansom and Biggin 2001). Moreover, INTs have been found to exhibit novel properties such as proton conduction, hydrogen-bond network, phase transitions, etc (Maniwa, Kumazawa et al 1999;Hummer, Rasaiah et al 2001;Koga, Gao et al 2001;Martí and Gordillo 2001;Noon, Ausman et al 2002;Mann and Halls 2003;Martí and Gordillo 2003;Mashl, Joseph et al 2003;Wang, Zhu et al 2004). Through a systematic investigation, we have revealed the geometrical structure adopted by INTs within SW-CNT and the signatures in its vibrational spectra (Feng, Zhang et al 2007).…”