  The stability of liquid crystal phases in presence of small amount of
non-mesogenic impurities is of general interest for a large spectrum of
technological applications and in the theories of binary mixtures. Starting
from the known phase diagram of the hard ellipsoids systems, we propose a
simple model and method to explore the stability of the nematic phase in
presence of small impurities represented by hard spheres. The study is
performed in the isobaric ensemble with Monte Carlo simulations.
