For binary solutions, the thermodynamic criterion which defines the spinodal curve is that the second derivative of free energy with respect to density or some composition variable is zero.
Extrema of the spinodal in a temperature vs composition plot coincide with those of the binodal curve, and are known as critical points. The spinodal itself can be thought of as a line of pseudocritical points, with the correlation function taking a scaling form with non-classical critical exponents. Strictly speaking, a spinodal is defined as a mean field theoretic object. As such, the spinodal does not exist in real systems, but one can extrapolate to infer the existence of a pseudospinodal that exhibits critical-like behavior such as critical slowing down.
In the case of ternary isothermal liquid-liquid equilibria, the spinodal curve (obtained from the Hessian matrix) and the corresponding critical point can be used to help the experimental data correlation process.
G. Astarita: Thermodynamics: An Advanced Textbook for Chemical Engineers (Springer 1990), chaps 4, 8, 9, 12.
Sandler S. I., Chemical and Engineering Thermodynamics. 1999 John Wiley & Sons, Inc., p 571.
Koningsveld K., Stockmayer W. H., Nies, E., Polymer Phase Diagrams: A Textbook. 2001 Oxford, p 12.
Koningsveld K., Stockmayer W. H., Nies, E., Polymer Phase Diagrams: A Textbook. 2001 Oxford, p 12.
Koningsveld K., Stockmayer W. H., Nies, E., Polymer Phase Diagrams: A Textbook. 2001 Oxford, p 12.
P.H. Mayrhofer et al. Progress in Materials Science 51 (2006) 1032-1114 doi:10.1016/j.pmatsci.2006.02.002 /wiki/Doi_(identifier)
Cahn RW, Haasen P. Physical metallurgy. 4th ed. Cambridge: Univ Press; 1996
Koningsveld K., Stockmayer W. H., Nies, E., Polymer Phase Diagrams: A Textbook. 2001 Oxford, p 12.
Sandler S. I., Chemical and Engineering Thermodynamics. 1999 John Wiley & Sons, Inc., p 557.
Koningsveld K., Stockmayer W. H., Nies, E., Polymer Phase Diagrams: A Textbook. 2001 Oxford, pp 46-47.
Koningsveld K., Stockmayer W. H., Nies, E., Polymer Phase Diagrams: A Textbook. 2001 Oxford, pp 46-47.
Saito, Y. (1978-02-01). "Pseudocritical Phenomena near the Spinodal Point". Progress of Theoretical Physics. 59 (2): 375–385. Bibcode:1978PThPh..59..375S. doi:10.1143/PTP.59.375. ISSN 0033-068X. https://academic.oup.com/ptp/article-lookup/doi/10.1143/PTP.59.375
MONETTE, L. (1994-05-30). "Spinodal Nucleation". International Journal of Modern Physics B. 08 (11n12): 1417–1527. Bibcode:1994IJMPB...8.1417M. doi:10.1142/s0217979294000646. ISSN 0217-9792. https://dx.doi.org/10.1142/s0217979294000646
Unger, Chris; Klein, W. (1984-03-01). "Nucleation theory near the classical spinodal". Physical Review B. 29 (5): 2698–2708. Bibcode:1984PhRvB..29.2698U. doi:10.1103/physrevb.29.2698. ISSN 0163-1829. https://dx.doi.org/10.1103/physrevb.29.2698
Marcilla, A.; Serrano, M.D.; Reyes-Labarta, J.A.; Olaya, M.M. (2012). "Checking Liquid-Liquid Critical Point Conditions and their Application in Ternary Systems". Industrial & Engineering Chemistry Research. 51 (13): 5098–5102. doi:10.1021/ie202793r. /wiki/Doi_(identifier)
Marcilla, A.; Reyes-Labarta, J.A.; Serrano, M.D.; Olaya, M.M. (2011). "GE Models and Algorithms for Condensed Phase Equilibrium Data Regression in Ternary Systems: Limitations and Proposals". The Open Thermodynamics Journal. 5: 48–62. doi:10.2174/1874396X01105010048. hdl:10045/19865. https://doi.org/10.2174%2F1874396X01105010048
Labarta, Juan A.; Olaya, Maria del Mar; Marcilla, Antonio (2015-11-27). "GMcal_TieLinesLL: Graphical User Interface (GUI) for the Topological Analysis of Calculated GM Surfaces and Curves, including Tie-Lines, Hessian Matrix, Spinodal Curve, Plait Point Location, etc. for Binary and Ternary Liquid -Liquid Equilibrium (LLE) Data". University of Alicante. hdl:10045/51725. https://hdl.handle.net/10045/51725