Results on a variety of mixedABO3oxides have revealed a pressure-induced ferroelectric-to-relaxor crossover and the continuous evolution of the energetics and dynamics of the relaxation process with increasing pressure. These common features have suggested a mechanism for the crossover phenomenon in terms of a large decrease in the correlation length for dipolar interactions with pressure a unique property of soft mode or highly polarizable host lattices. The pressure effects as well as the interplay between pressure and dc biasing fields are illustrated for some recent results on PZN−9.5 PT, PMN and PLZT 6/65/35. ©2000 American Institute of Physics.