Abstract
It is found experimentally that the coexistence region of a vapor-liquid system or a binary mixture is substantially narrowed when the fluid is confined in an aerogel with a high degree of porosity (e.g., of the order of 95 to 99%). A Hamiltonian model for this system has recently been introduced [1]. We have performed Monte-Carlo simulations for this model to obtain the phase diagram for the model. We use a periodic fractal structure constructed by diffusion-limited cluster-cluster aggregation (DLCA) method to simulate a realistic gel environment. The phase diagram obtained is qualitatively similar to that observed experimentally. We also have observed some metastable branches in the phase diagram which have not been seen in experiments yet. These branches, however, might be important in the context of recent theoretical predictions and other simulations.
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References
1._J. Donley and A. Liu, Phase behavior of near-critical fluids confined in periodic gels, Phys. Rev. E 55, 539–543 (1997).
A. Wong and M. Chan, Liquid-vapor critical point of 4He in aerogel, Phys. Rev. Lett. 65, 2567–2570 (1990).
A.P.Y. Wong, S.B. Kim, W.I. Goldburg, and M.H.W. Chan, Phase separation, density fluctuation, and critical dynamics of N2 in aerogel, Phys. Rev. Lett. 70, 954–957 (1993).
Z. Zhuang, A.G. Casielles, and D.S. Cannell, Phase diagram of isobutyric acid and water in dilute silica gel, Phys. Rev. Lett. 77, 2969–2972 (1996).
S.B. Kim, J. Ma, and M.H.W. Chan, Phase diagram of 3He-4He mixture in aerogel, Phys. Rev. Lett. 71, 2268–2271 (1993).
A. Maritan, M.R. Swift, M. Cieplak, M.H.W. Chan, and M.W. Cole, Ordering and phase transitions in random-field ising systems, Phys. Rev. Lett. 67, 1821–1824 (1991).
E. Pitard, M.L. Rosinberg, G. Stell, and G. Tarjus, Critical behavior of a fluid in a disordered porous matrix: An Ornstein-Zernike approach, Phys. Rev. Lett. 41, 4361–4364 (1995).
A. Falicov and A. Berker, Correlated random-chemical-potential model for the phase transitions of helium mixtures in porous media, Phys. Rev. Lett. 74, 426–429 (1995).
H. Nakanishi and M. Fisher, Critical points shifts in films, J. Chem. Phys. 78, 3279–3293 (1983).
P. Meakin, Formation of fractal clusters and networks by irreversible diffusion-limited aggregation, Phys. Rev. Lett. 51, 1119 (1983).
M. Kolb, R. Botet, and R. Jullien, Hierarchical model for irreversible kinetic cluster formation, J. Phys. A 17, L75 (1983).
R. Jullien and R. Botet, Aggregation and Fractal Aggregates (World Scientific, Singapore, 1986).
A. Hasmy, E. Anglaret, M. Foret, J. Pelous, and R. Jullien, Small-angle neutron-scattering investigation of long-range correlations in silica aerogels: Simulations and experiments, Phys. Rev. B 50, 6006–6016 (1994).
N. Metropolis, A.W. Rosenbluth, M.N. Rosenbluth, and A.H. Teller, Equation of state calculations by fast computing machines, J. Chem. Phys. 21, 1087–1092 (1953).
K. Huang, Statistical Mechanics (John Wiley and Sons, New York, 1987).
K.S. Page and P.A. Monson, Phase equilibrium in a molecular model of a fluid confined in a disordered porous material, Phys. Rev. E 54, R29–R32 (1996).
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Salazar, R., Toral, R. & Chakrabarti, A. Phase Behavior of Binary Fluid Mixtures Confined in a Model Aerogel. Journal of Sol-Gel Science and Technology 15, 175–181 (1999). https://doi.org/10.1023/A:1008795623646
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DOI: https://doi.org/10.1023/A:1008795623646