Phase diagrams of the Blume–Emery–Griffiths model with site dilution (original) (raw)

Cluster variational method in pair approximation has been extended for the description of the site-diluted Blume}Emery}Gri!ths model with spin 1. The phase diagrams for the case of dilution are discussed in the presence of biquadratic interactions and single-ion anisotropy. In particular, the critical concentrations for the ferromagnetic and staggered quadrupolar phases, as well as the shift of tricritical point as a result of dilution have been studied. The numerical calculations are presented for a bilayer system with the coordination number z"5.