Critical phenomena in ionic fluids: A systematic investigation of the crossover behavior
- Department of Chemistry and Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)
The critical behavior of turbidity for an array of ionic fluids is reported. The ionic fluid is comprised of a low melting organic salt in an organic solvent, and the critical temperature ({ital T}{sub {ital c}}) refers to the liquid--liquid coexistence. The phase separation is driven, predominantly, by Coulombic interactions in the low dielectric constant ({epsilon}) solvents and, primarily, by solvophobic effects in the high {epsilon} solvents. For the moderately Coulombic case, the critical exponents of osmotic compressibility and correlation length ({gamma} and {nu}, respectively), which are deduced from turbidity, exhibit a {ital crossover} from their Ising to mean-field values when moved away from the {ital T}{sub {ital c}}. The crossover region moves closer to {ital T}{sub {ital c}} as the effective {epsilon} of the solvent is decreased. For the solvophobic case, the critical behavior of turbidity can be adequately described by Ising critical exponents without correction-to-scaling terms. In addition, several specific features of this class of ionic fluids are presented. Some potential factors that influence the values of the critical exponents are also discussed.
- OSTI ID:
- 46336
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 20 Vol. 102; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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