  We compute the equilibrium concentration of stacking faults and point defects
in polydisperse hard-sphere crystals. We find that, while the concentration of
stacking faults remains similar to that of monodisperse hard sphere crystals,
the concentration of vacancies decreases by about a factor two. Most
strikingly, the concentration of interstitials in the maximally polydisperse
crystal may be some six orders of magnitude larger than in a monodisperse
crystal. We show that this dramatic increase in interstitial concentration is
due to the increased probability of finding small particles and that the
small-particle tail of the particle size distribution is crucial for the
interstitial concentration in a colloidal crystal.
