Piezoresponse Force Microscopy Studies of Domain in Ba_1-xSr_xTiO₃ Ceramics

The character of the domain structures in Ba1-xSrxTiO3 (x=0.7, 0.4, 0.1) ceramics prepared by the solid-state reaction was investigated by piezoresponse force microscope (PFM) and transmission electron microscope (TEM). The PFM results indicate that the domains are induced in paraelectric phase Ba0.6Sr0.4TiO3 under 10V dc voltage applied between the tip and the bottom electrode. However, no domain appears in paraelectric phase Ba0.3Sr0.7TiO3 under the same external voltage. The polarization reversal occurs in Ba0.9Sr0.1TiO3 after application of 12V and -12V dc bias voltage. Furthermore, the TEM images show that no domain is found in Ba0.6Sr0.4TiO3, while the herringbone domain structure is found in Ba0.9Sr0.1TiO3. The mechanism of nonlinear dielectric properties of paraelectric phase Ba1-xSrxTiO3 ceramic is also discussed.