Condensation of Fluids Confined in Non-rigid Nanopores: With a Little Help from the Substrate

• Published in: Journal of low temperature physics 2009-11, Vol.157 (3-4), p.382-394
• Main Authors: Gatica, Silvina M., Kim, Hye-Young
• Format: Article
• Language: English
• Subjects: Bundles; Carbon nanotubes; Characterization and Evaluation of Materials; Computational fluid dynamics; Condensed Matter Physics; Fluid flow; Fluids; Magnetic Materials; Magnetism; Nanomaterials; Nanostructure; Physics; Physics and Astronomy; Porosity
• ISSN: 0022-2291; 1573-7357
• DOI: 10.1007/s10909-009-9898-7

Fluids adsorbed in nanopores exert a force on the substrate that produces a compression or expansion of the host. Although this effect has been observed experimentally and computationally, an overwhelming majority of the theoretical studies have assumed that the environment provides a fixed, static potential in which the adsorbate moves. In a recent paper (H.-Y. Kim, S.M. Gatica, G. Stan and M.W. Cole, J. Low Temp. Phys. (this issue) 2009 ) we showed that the relaxation of the substrate is not limited to affecting the capacity of uptake, but has dramatic consequences on the physical properties of the adsorbates, like phase transitions and the energetics in low dimensions. For example, 3 He in a rigid 1D pore is a gas, and in a non-rigid carbon nanotube is a liquid. In this paper we explore more situations involving classical and quantum fluids in slit pores and in bundles of carbon nanotubes. We find that, due to the cooperation of the relaxing substrate, confined classical gases condense at higher temperatures compared to extremely rigid substrates and 3 He has a cohesive energy of up to 9.5 K when confined within a narrow non-rigid slit pore. We observe that a compression of a bundle of nanotubes of less than 0.02% gives rise to changes of up to 9% in the critical temperature.