Structure and Dynamics of Ferroelectric Domains in Polycrystalline Pb(Fe_1/2Nb_1/2)O₃

A complex domain structure with variations in the morphology is observed at ambient temperature in monoclinic Pb(Fe_1/2Nb_1/2)O₃. Using electron microscopy and piezoresponse force microscopy, it is possible to reveal micrometre-sized wedge, lamellar-like, and irregularly shaped domains. By increasing the temperature, the domain structure persists up to 80 °C, and then starts to disappear at around 100 °C due to the proximity of the ferroelectric-paraelectric phase transition, in agreement with macroscopic dielectric measurements. In order to understand to what degree domain switching can occur in the ceramic, the mobility of the domain walls was studied at ambient temperature. The in situ poling experiment performed using piezoresponse force microscopy resulted in an almost perfectly poled area, providing evidence that all types of domains can be easily switched. By poling half an area with 20 V and the other half with -20 V, two domains separated by a straight domain wall were created, indicating that Pb(Fe_1/2Nb_1/2)O₃ is a promising material for domain-wall engineering.