Investigation of the ferroelectric-relaxor transition in PbMg1/3Nb2/3O3–PbTiO3 ceramics by piezoresponse force microscopy

The spontaneous transition between the ferroelectric and relaxor states was investigated in 0.86PbMg1/3Nb2/3O3–0.14PbTiO3 ceramics using piezoresponse force microscopy (PFM). Macroscopically, the transition from the ferroelectric to relaxor phases manifests itself by an anomaly in the temperature dependences of the dielectric permittivity and by a sharp decline of the remanent polarization. Alternatively, PFM reveals a decay of the ferroelectric micron-size domains at the macroscopic Curie temperature, TC. Simultaneously, smaller domains of submicron sizes are observed at temperatures appreciably above TC, being concentrated near grain boundaries. It is argued that the particular mechanical and electrical conditions at the grain boundaries promote nucleation of the ferroelectric phase.