Wideband dielectric spectroscopy of (Sr0.7Bi0.2)TiO3 ceramics and its microscopic mechanism of polarization
Wideband dielectric spectroscopy of (Sr0.7Bi0.2)TiO3 ceramics and its microscopic mechanism of polarization
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DOI：
10.2109/jcersj2.16023
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发表时间：
2016-06
影响因子：
1.1
通讯作者：
Motoharu Sakurai;Kazuki Kanehara;H. Takeda;T. Tsurumi;T. Hoshina
中科院分区：
文献类型：
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作者：
Motoharu Sakurai;Kazuki Kanehara;H. Takeda;T. Tsurumi;T. Hoshina
(Sr采用固相反应法制备了（Sr0.7Bi0.2）TiO3陶瓷，并测量了其宽带介电谱，以了解其微观极化机理。结果表明，（Sr0.7Bi0.2）TiO3陶瓷在2 5 °C下的介电常数主要由离子极化和偶极极化共同决定，而SrTiO3陶瓷的介电常数主要由离子极化决定。介电常数的温度依赖性表明，（Sr0.7Bi0.2）TiO3陶瓷属于弛豫型铁电体，其中Bi3+离子的偏置有助于形成极性纳米区（PNR）。偶极极化的起源被认为是PNR的偶极涨落。另一方面，与SrTiO3陶瓷相比，（Sr0.7Bi0.2）TiO3陶瓷的离子极化受到Sr位空位的抑制。（Sr0.7Bi0.2）TiO3陶瓷的高介电常数主要是由于PNR的偶极涨落引起的偶极极化所致。
(Sr 0.7 Bi 0.2 )TiO 3 ceramics were fabricated by a solid state reaction, and a wideband dielectric spectrum was measured for understanding the microscopic polarization mechanism of (Sr 0.7 Bi 0.2 )TiO 3 ceramics. It was revealed that the dielectric permittivity of (Sr 0.7 Bi 0.2 )TiO 3 ceramics at 25°C was determined by dipole polarization as well as ionic polarization, whereas the permittivity of SrTiO 3 is mainly determined only by ionic polarization. The temperature dependence of permittivity suggested that (Sr 0.7 Bi 0.2 )TiO 3 ceramics belongs to ferroelectric relaxor, in which off-center Bi 3 + ions contribute to the formation of polar nanoregions (PNRs). The origin of the dipole polarization is considered the dipole fl uctuations of PNRs. On the other hand, the ionic polarization of (Sr 0.7 Bi 0.2 )TiO 3 ceramics was suppressed by an in fl uence of Sr-site vacancy, compared to that of SrTiO 3 . High permittivity of (Sr 0.7 Bi 0.2 )TiO 3 ceramics is mainly due to the dipole polarization associated with dipole fl uctuation of PNRs.