Ba_(1-x)Sr_xTiO_3陶瓷电畴的压电响应力显微研究

Piezoresponse Force Microscopy Studies of Domain in Ba_(1-x)Sr_xTiO_3 Ceramics

采用常规固相反应法制备了Ba1-xSrxTiO3(x=0.7,0.4,0.1)陶瓷,利用扫描力显微镜的压电响应模式得到了压电响应像,并观察到了外加直流电压时的电畴诱导和极化反转.在10V电压下(样品厚90μm,下同),室温时顺电体Ba0.6Sr0.4TiO3中诱导出了铁电畴,而顺电体Ba0.3Sr0.7TiO3中并未诱导出铁电畴.12V和-12V电压下,Ba0.9Sr0.1TiO3中的电畴发生了明显的极化反转.对x=0.4、0.1的样品使用透射电子显微镜进行观察,发现室温下前者无电畴,进一步验证了压电响应图像的结果;后者有电畴,且为鱼刺状的畴结构.同时对顺电相Ba1-xSrxTiO3材料中非线性介电特性的起源进行了探讨。

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.