Figure 2.

Temperature dependence of the complex dielectric permittivity of (a) PbTiO₃ perovskite ferroelectric, (b) canonical relaxor PbMg_1/3Nb_2/3O₃, and (c) dipolar glass (betaine–phosphate)_0.15(betaine–phosphite)_0.85. A typical ferroelectric hysteresis loop is presented in the inset in (a). Inset in (b) shows a classical example of dipole frustration in the antiferrommagnetic Ising model on a 2D triangular lattice. (a) Adapted with permission from ref (154). Copyright 1971 Taylor & Francis. (b) Adapted with permission from ref (62). Copyright 2006 Springer Nature. (c) Adapted with permission from ref (153). Copyright 1996 IOP Publishing.