CONCLUSION

We have used Gibbs-ensemble MC simulations to study the phase behavior of a binary rod-plate mixture of ellipsoidal particles with aspect ratio =15. At high pressures, i.e. not in the isotropic phase, stable uniaxial and phases as well as the biaxial phase were found. For compositions around the mixture appeared to phase separate into a plate-rich nematic and a biaxial phase B. The shapes of the two-phase region, and the region where the biaxial phase region is stable, are both asymmetric. This is probably due to the difference in the third and higher virial coefficients of the rods compared to the plates. Our simulations support the conclusions of ref. [121] that phase separation competes with the formation of a biaxial phase in a mixture of prolate and oblate particles. Two factors favor the formation of a biaxial phase:

1. the use of highly anisometric particles in the mixture [121] and
2. the use of particle mixtures for which the second virial coefficient for interaction between like components is equal to the corresponding coefficient that describes the interaction between unlike components [130].