Abstract
A spin-1 Ising model, which simulates the thermodynamic behavior of - mixtures along the line and near the critical mixing point, is introduced and solved in the mean-field approximation. For reasonable values of the parameters of the model the phase diagram is qualitatively similar to that observed experimentally and the phase separation appears as a consequence of the superfluid ordering. Changing the parameters produces many different types of phase diagram, including as features lines, critical points, tricritical points, and triple points. Certain thermodynamic features which differ from the - experiments may be artifacts of the mean-field theory.
- Received 23 March 1971
DOI:https://doi.org/10.1103/PhysRevA.4.1071
©1971 American Physical Society