Relaxor ferroelectrics microstructures

Figure 6.20 Schematic development of relaxor ferroelectric microstructures with temperature...

Cheng ZY, Zhang QM, Bateman FB (2002) Dielectric relaxation behavior and its relation to microstructure in relaxor ferroelectric polymers high-energy electron irradiated poly(vinylidene fluoridetrifluoroethylene) copolymers. J Appl Phys 92 6749... 

Another exanple of this type of microstructure is provided by the relaxor ferroelectrics related to PbMgj Nb Oj. These have a structure described as consisting of polar nanoregions, coherently intergrown within the crystal matrix and sensitive to temperature (Section 6.7). Similarly, the oxide Sm, 8,5Ba3 is nominally... 

Finally we can note that the ferroelectric state of relaxors is characterised by an extremely narrow hysteresis loop with a low value for the remanent polarisation (Figure 6.19a). This sort of hysteresis loop can be considered to fall into the continuum described previously (Figure 6.9) and suggests that the microsttucture of the phases is at an even more reduced scale than the fine-grained ceramic samples. Indeed, the behaviour when the materials are either cooled in or without an external electric field (FC or ZFC) is also taken as indicative of a complex microstructure. The strain versus applied electric field loop has a U shape, rather like the central portion of the strain curve for an antiferroelectric (Figure 6.19b). 

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