Advanced Solid State Physics

(a) (b)

Figure 136: a) Pyroelectric constant ofPbTiO 3 ; b) Dielectric constant ofPbTiO 3

Figure 137: Graphical description for pyroelectricity, ferroelectricity, antipolarity and
antiferroelectricity

Antipolars and antiferroelectrics also behave the same without an electric field, but in contrast to
pyroelectric and ferroelectric materials they don’t exhibit a macroscopic polarization belowTC. By
applying an electric field however, the antiferroelectric material behaves the same as the ferroelectric
material belowTC, while the polarization of the antipolar material doesn’t change at all.

14.4.7 Piezoelectricity

This material property is related to pyro- and ferroelectricity in a sense, that the crystal gets longer,
when an electric field is applied. This happens, because the electric field couples with the polarization,
which stretches the dipols apart and thus the material expands. Hence, in order to become piezoelec-
tric, a material first has to show a spontaneous polarization.
The most commonly used piezoelectric materials are: PZTs(Pb[ZrxTi 1 −x]O 3 , 0 < x <1),BaTiO 3 ,