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中国物理学会期刊

α-LiIO3的导电和介电特性的理论分析

CSTR: 32037.14.aps.26.500

THEORETICAL ANALYSIS OF THE ELECTRICAL CONDUCTION AND DIELECTRIC BEHAVIOR OF α-LiIO3 SINGLE CRYSTALS

CSTR: 32037.14.aps.26.500
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  • 本文考虑到α-LiIO3电导的强烈各向异性,利用一维Debye-Hückel方程和泊松方程,导出了表观直流电导率,解释了文献1中有关α-LiIO3的各种静态电导特性。推导中假设晶体界面处的电流由速率过程决定,并考虑了晶体两端的不对称性(电极性)。并援引文献2中有关动态介电常数的结果,部分解释了文献1中有关α-LiIO3在加直流偏压场和不加偏压场的介电行为。文中指出,文献3中提到的联结α-LiIO3晶体两极性面观察到持续不变的微弱电流,以及我们实验室观察到成极的铁电晶体铌酸锶钡也有同样现象,均来源于晶体极性电动势。这一电动势与晶体的自发极化Ps同时存在。

     

    By using the Debye-Hückel equation and the Poisson equation, the almost one-dimensional ionic conductive behaviors of α-LiIO3 have been analysed theoretically. The current across the boundaries between the crystal and metallic electrodes is con-sidered to be limited by rate processes. The asymmetry of the ± c-directions due to spontaneous polarization of the crystal has been taken into consideration. The explicit expression derived for the apparent DC conductivity is satisfactory in explaining the characteristic behavior of α-LiIO3, e.g., the dependence of conductivity on applied voltage, as shown experimentally in 1. The functional relationship between the AC dielectric constant and the bias field (cf. 1) is interpreted partially by following the approach given in 2. It is also pointed out that the weak current constantly flowing through the wire connecting the end surfaces of opposite polarity of an α-LiIO3 single crystal (cf. 3), as well as similar phenomena observed in our own laboratory on poled ferroelectrics such as BaxSr1-xNb2O6(x~1/3), are caused by the crystal-line polarity EMF. This EMF coexists with the spontaneous, polarization Ps.

     

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