摘要
应用特殊的锁相放大器,在-20℃至180℃范围内测量了三种高绝缘体的表面和体电导,观察到传导极化子的跳跃导电和能带导电;LiNbO_3,中两种导电态的转变温度为38℃,传导极化子可以被陷阱俘获而成为束缚极化子。后者不是载流子,但在外电场作用下能产生位移运动而提供超低频电极化效应。LiNbO_3和LiTaO_3的表面存在大量铁电屏蔽电荷,但它们的表面传导电流却不比玻璃的大,而是提供了特别大的位移电流。显得这些屏蔽电荷是处于束缚极化子态,在45,75和130℃附近,观察到LiNbO_3中的位移电流出现异常的现象。
Using a special lock-in amplifier, the surface and volume conductivities of three kinds of high insulators are measured from -20℃ to 180℃. Hopping and band conductions of conductive polarons are observed in LiNbO3, the transition temperature between the two- conductive states is about 38℃. A conductive polaron can be captured by a trap and becomes a bound polaron. The bound polaron is not an electric carrier, but under the action of external field, its position may be changed to give an ultralow frequency polarization effect. There are many ferroelectric screenning charges on the surface of LiNbOa and LiTaO2, however, their conductive currents are not so large as those of glass. But the screenning charges supply very large displacement currents. The fact shows that these screenning charges are in bound polaron state. The phenomenon of that the displacement current shows anomalous at about 45, 75, and 130℃ is observed in LiNbO3.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
1992年第11期1898-1905,共8页
Acta Physica Sinica
基金
高等学校博士学科点专项科研基金
