Quasi-one- and two-dimensional transitions of gases adsorbed on nanotube bundles

Gatica, Silvina M.; Bojan, Mary J.; Stan, George; Cole, Milton W.

doi:10.1063/1.1339886

Cited by 94 publications

(94 citation statements)

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“…In recent years much experimental effort has been devoted to the study of structural and thermal properties of such systems and a number of theoretical models have been advanced to predict these properties [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. However, the thermal expansion behavior of SWNT-gas impurity systems still remains obscure.…”

Section: Introductionmentioning

confidence: 99%

Radial thermal expansion of pure and Xe-saturated bundles of single-walled carbon nanotubes at low temperatures

Долбин

Esel'son

Gavrilko

et al. 2009

Low Temperature Physics

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The radial thermal expansion coefficient α r of pure and Xe-saturated bundles of singlewalled carbon nanotubes has been measured in the interval 2.2-120 K. The coefficient is positive above T = 5.5 K and negative at lower temperatures. The experiment was made using a low temperature capacitance dilatometer with a sensitivity of 2·10 -9 cm and the sample was prepared by compacting a CNT powder such that the pressure applied oriented the nanotube axes perpendicular to the axis of the cylindrical sample. The data show that individual nanotubes have a negative thermal expansion while the solid compacted material has a positive expansion coefficient due to expansion of the intertube volume in the bundles. Doping the nanotubes with Xe caused a sharp increase in the magnitude of α r in the whole range of temperatures used, and a peak in the dependence α r (T) in the interval 50-65 K. A subsequent decrease in the Xe concentration lowered the peak considerably but had little effect on the thermal expansion coefficient of the sample outside the region of the peak. The features revealed have been explained qualitatively.

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Section: Introductionmentioning

confidence: 99%

Radial thermal expansion of pure and Xe-saturated bundles of single-walled carbon nanotubes at low temperatures

Долбин

Esel'son

Gavrilko

et al. 2009

Low Temperature Physics

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“…cylindrical pore with multiple layers, we assume the interlayer spacing is constant, ∆ = 0.3354 nm (Charlier and Michenaud 1993;Ge and Sattler 1993). To investigate the effects of surface strength, we choose a cylindrical pore whose surface is graphite-like but its well-depth is 60% that of graphite, i.e.…”

Section: Solid-fluid Potentialmentioning

confidence: 99%

“…Jakubek and Simard (2004) reported the formation of two condensed phases of argon adsorbed onto single-walled carbon nanotubes and found the critical pressures of the onset of the quasi-one-dimensional linear phase and the quasi-two-dimensional monolayer phase formation on the external surface at 77 K and 87.3 K, respectively. A number of workers (Gatica et al 2001(Gatica et al , 2008Gatica and Cole 2005;Urban et al 2005) have undertaken theoretical investigations of the quasi-1D and -2D phase transitions for gases adsorbed onto nanotube bundles. Recently, Wang et al (2010), using carbon nanotubes as resonators, have observed the formation of argon monolayers on the cylindrical surface and a phase transition from fluid to solid at temperatures below 77 K. The effects of surface curvature on the adsorption of nitrogen at 77 K in SWCNTs have been studied by Ohba et al (2007), both experimentally and using GCMC simulation for nanotubes with diameters distributed around 2.8 nm.…”

Section: Introductionmentioning

confidence: 99%

“…Many investigations have been carried out to study phase transitions (2D transition and capillary condensation) on planar surfaces, slit and cylindrical pores (Migone et al 1984;Ball and Evans 1988;Youn and Hess 1990;Curtarolo et al 2000;Gatica et al 2001;Gatica and Cole 2005;Do et al 2009;Hamada et al 2009;Wang et al 2010). The critical properties of confined fluids in nano-scale porous materials vary significantly with the pore geometry and the surface strength (Panagiotopoulos 1987;Ortiz et al 2005).…”

Section: Introductionmentioning

confidence: 99%

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Effects of Surface Curvature and Surface Strength on Argon Adsorption in Carbon Nanotubes at Temperatures below the Triple Point

Liu

Nicholson

et al. 2010

Adsorption Science & Technology

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This paper describes an investigation of argon adsorption into carbon nanotubes at temperatures below the triple point, using a grand canonical Monte Carlo simulation to study the effects of confinement and surface strength on the 2D transition. In large pores, it was found that 2D transitions can occur in more than one layer, but are absent in higher layers for small pores. The 2D critical temperature of the first layer for a small pore (R = 1.2 nm) was found to be ca. 66 K (MWCNT) and 65 K (SWCNT), compared to 55-59 K observed experimentally for a flat graphite surface. This is because of the overlapping effects due to the surface curvature or the confinement in a carbon nanotube. Assuming a weaker carbon surface by reducing the graphene surface strength by 40% for SWCNT, the 2D critical temperature was only modestly reduced to 63 K. This suggests that the experimental data at 59 K might be attributed to other factors, other than confinement effects. An imperfect surface is suggested and, employing 5% defects on this surface, the 2D critical temperature has been determined as 58 K which is in better agreement with the experimental value of 59 K.

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“…163,192 One-dimensional (1-d) and quasi-1-d phases are possible for gases adsorbed on SWNT bundles. 32,33,[193][194][195] As-prepared SWNTs are capped, making endohedral adsorption unlikely to occur to any significant extent. Many careful experimental studies of gas adsorption on closed SWNT bundles have been performed, yielding adsorption isotherms, binding energies, and isosteric heats of adsorption (q st ).…”

Section: Introductionmentioning

confidence: 99%

University/NETL Student Partnership Program

Holder¹

2003

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Renewed interest in methane hydrates as a potential, unconventional energy source has prompted investigation into their thermal properties, which are necessary to determine heat flow through the hydrate for resource production.In this investigation thermal property measurements have been made on unconsolidated pure methane hydrate samples formed in a high-pressure variable-volume viewcell (HVVC). Using a transient plane source (TPS) technique, a single measurement was used tosimultaneously determine the thermal conductivity and thermal diffusivity of the methane hydrate inside the viewcell. A vessel was designed to contain the sample around the TPS for thermal property measurements while inside the HVVC. The vessel was successful in containing the sample during the hydrate formation experiments and its design made it possible to recover a methane hydrate sample, which was analyzed with Raman spectroscopy.The striking quality of methane hydrate is that its thermal conductivity is much lower than ice, despite its structural similarities to ice. The thermal conductivity of pure methane hydrate for a temperature range of 264 K to 277 K and pressure range of 11.6 MPa to 13.0 MPa, respectively, can be described by k = (-0.0034 T + 1.2324) W/mK, where T is in Kelvin. The average of the thermal conductivity values within this range of temperatures and pressures is k = 0.30 ± 0.02 W/mK. The sample was recovered and analyzed with Raman spectroscopy, confirming that the sample was pure hydrate.The thermal diffusivity of methane hydrate has only been reported by one other investigator in preliminary experiments. The thermal diffusivity of methane hydrates determined in the work reported herein for a temperature range of 264 K to 277 K and pressure range of 11.6MPa to 13.0 MPa, respectively, is α = (2.59 ± 0.16) × 10 -7 m 2 /s. The thermal diffusivity can also be described by α × 10 7 = (0.0005 T + 2.4424) m 2 /s where T is in Kelvin.iv Derivation ...................................................................................................................................116 Different τ -Values ...................................................... Dr. Gerald Holder, Dean of Engineering at the University of Pittsburgh, was my research advisor and though his role was remote, his support, knowledge, and advice was integral to my work. B.1.2 H(τ) Values From Numerical Integration at LIST OF TABLES LIST OF FIGURESI would like to thank Ronald Lynn of NETL. Ron played an integral role in upgrading and automating our experimental setup. He wrote the data acquisition program, automating data collection. He supplied his vast knowledge of National Instrument's software and hardware and was a great resource for learning LabVIEW.Dr. David Shaw of Geneva College developed most of the data analysis described here. He hired me as a research assistant while I was an undergraduate which led to an internship at NETL. As such, I was able to continue this work as a graduate student at Pitt. I thank him for his vast knowledge and w...

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Quasi-one- and two-dimensional transitions of gases adsorbed on nanotube bundles

Cited by 94 publications

References 28 publications

Radial thermal expansion of pure and Xe-saturated bundles of single-walled carbon nanotubes at low temperatures

Radial thermal expansion of pure and Xe-saturated bundles of single-walled carbon nanotubes at low temperatures

Effects of Surface Curvature and Surface Strength on Argon Adsorption in Carbon Nanotubes at Temperatures below the Triple Point

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