97-10U

A disordered model for ferroelectrics of order--disorder type with asymmetric double-well potential is considered. Thermodynamic and dynamic properties of the model are studied within two-site cluster approximation for short-range interaction and mean field approximation for long-range interaction. Both annealed and quenched types of disorder are studied. The results provide good quantitative description for dielectric measurements in crystals of Rochelle salt, $RbHSO_4$ and their deuterated isomorphs.