Mean-field critical behaviour for a fully frustrated Blume–Emery–Griffiths model

We present a mean-field analysis of a fully frustrated Ising spin model on an Ising lattice gas. This is equivalent to a degenerate Blume–Emery–Griffiths model with frustration, which we analyse for different values of the quadrupolar interaction. We find that the regular disorder shifts the tricritical point to lower temperatures.