Experimental and theoretical study of the influence of disorder on diffuse first-order phase transitions: NaNbO3: Gd and KTaO3: Li as examples

We consider consequences of local disorder in systems experiencing first order phase transitions. Such systems can be of rather different nature. For example, manganates showing gigantic magnetoelectric effect, doped antiferroelectrics or biomembranes. Monte-Carlo computations performed have shown that the disorder increases the temperature interval where the high- and lowtemperature phases coexist and this provides thermodynamics in the disordered systems distinct from the thermodynamics of classical homogeneous systems.