Frequency-dependent conductive behavior of polymer-derived amorphous silicon carbonitride
Frequency-dependent conductive behavior of polymer-derived amorphous silicon carbonitride
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DOI：
10.1016/j.actamat.2015.02.020
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发表时间：
2015-05
期刊：
影响因子：
9.4
通讯作者：
Baisheng Ma;Yiguang Wang;Kewei Wang;XuQin Li;Jinling Liu;L. An
中科院分区：
文献类型：
--
作者：
Baisheng Ma;Yiguang Wang;Kewei Wang;XuQin Li;Jinling Liu;L. An
系统地研究了聚合物衍生的非晶碳氮化硅陶瓷的交流导电性能。电导率表现出频率依赖的开关：在低频时，电导率是恒定的，与频率无关；而在高频率下，电导率随频率增加而增加，表现出较强的弛豫过程。与频率无关的电导率和弛豫的特征频率对于退火温度都遵循Arrhenius关系，对于测试温度则遵循带尾跳变过程。XPS分析表明，随着退火温度的升高，材料的自由碳相发生了asp3 - sp2相变。跃迁的活化能与阿伦尼乌斯关系相似。研究人员提出了以下导电机制来解释所观察到的行为：低频区与频率无关的电导率主要由电荷载流子通过无基体碳路径的长距离传输主导，并受到电场浓度效应的增强；而高频区的频率相关电导率主要受自由碳相中载流子弛豫控制的界面极化过程控制。
The AC conductive behavior of a polymer-derived amorphous silicon carbonitride ceramic was systemically studied. The conductivity exhibited a frequency-dependent switch: at low frequencies, the conductivity is constant and independent of frequency; while at high frequencies, the conductivity increases with frequency, showing a strong relaxation process. Both the frequency-independent conductivity and the characteristic frequency for the relaxation follow the Arrhenius relation with respect to the annealing temperature and follow a band-tail hopping process with respect to the testing temperature. XPS analysis revealed that asp3–sp2transition took place in the free-carbon phase of the material with increasing annealing temperature. The activation energy of the transition is similar to those for the Arrhenius relations. The following conductive mechanisms were proposed to account for the observed behaviors: the frequency-independent conductivity in the low frequency region is dominated by a long-distance transport of charge carriers via matrix-free carbon path, enhanced by an electric-field concentration effect; while the frequency-dependent conductivity in the high frequency region is dominated by a interfacial polarization process governed by charge carrier relaxation within the free-carbon phase.