Summary

In this section, we discussed ferroelectric materials which are characterized by Noncentrosymmetric structure materials exhibiting a polar axis whose direction can be reversed by changing the direction of applied field. These materials also follow a Curie-Weiss behavior, i.e. a transition from ferroelectric to paraelectric phase upon heating across a Curie temperature, T_c.  The nature of phase transition can be first or second order depending upon the type of material which is reflected in the way polarization changes as a function of temperature. Ferroelectric materials when switched under alternating fields, show a typical hysteresis like behavior showing two stable polarization states +P_R and –P_R which are useful for memory application where these can be used as stated ‘0’ and ‘1’ for binary data storage. The reversal of polarization takes place by domain reversal which is a phenomenon happening by nucleation and growth of new domains. Typical examples of commonly used ferroelectric materials are perovskite structured compounds e.g. PbTiO₃, BaTiO₃, Pb(Zr,Ti)O₃. One of the most touted applications of ferroelectric materials is in nonvolatile ferroelectric memories besides other applications such as flash bulbs, and sensors and actuators.