Thermodynamic properties of one-dimensional dilute Ising systems with interacting impurities

The thermodynamic properties of the one-dimensional annealed Ising binary alloy are exactly calculated in the absence of an external magnetic field. Nearest-neighbour interactions between host atoms, host atoms and magnetic impurities, and between these impurities are taken into account. The results are compared with the quenched alloy model and with the average homogeneous system. Significant deviations appear between the annealed and the quenched systems for the entropy and the free energy owing to the fact that the annealing process allows the system to reach the true equilibrium. On the contrary these two models exhibit quite a similar behaviour for the specific heat and the internal energy when the three exchange interactions have nearly equal values.