Institute of Thermal and Nuclear Power Engineering, National Research University MPEI, 111250 Moscow, Russia.
Joint Institute of High Temperatures RAS, 125412 Moscow, Russia.
Int J Mol Sci. 2020 Oct 15;21(20):7634. doi: 10.3390/ijms21207634.
Carbon nanocomposites present a new class of nanomaterials in which conducting carbon nanoparticles are a small additive to a non-conducting matrix. A typical example of such composites is a polymer matrix doped with carbon nanotubes (CNT). Due to a high aspect ratio of CNTs, inserting rather low quantity of nanotubes (on the level of 0.01%) results in the percolation transition, which causes the enhancement in the conductivity of the material by 10-12 orders of magnitude. Another type of nanocarbon composite is a film produced as a result of reduction of graphene oxide (GO). Such a film is consisted of GO fragments whose conductivity is determined by the degree of reduction. A distinctive peculiarity of both types of nanocomposites relates to the dependence of the conductivity of those materials on the applied voltage. Such a behavior is caused by a non-ideal contact between neighboring carbon nanoparticles incorporated into the composite. The resistance of such a contact depends sharply on the electrical field strength and therefore on the distance between neighboring nanoparticles. Experiments demonstrating non-linear, non-Ohmic behavior of both above-mentioned types of carbon nanocomposites are considered in the present article. There has been a model description presented of such a behavior based on the quasi-classical approach to the problem of electron tunneling through the barrier formed by the electric field. The calculation results correspond qualitatively to the available experimental data.
碳纳米复合材料是一类新型纳米材料，其中导电碳纳米颗粒是作为非导电基体的少量添加剂。此类复合材料的典型例子是聚合物基体掺杂碳纳米管（CNT）。由于 CNT 的高纵横比，插入少量的纳米管（在 0.01%的水平）就会发生渗流转变，这使得材料的电导率提高了 10-12 个数量级。另一种纳米碳复合材料是氧化石墨烯（GO）还原的产物。这种薄膜由 GO 片段组成，其电导率取决于还原的程度。这两种类型的纳米复合材料的一个显著特点是，这些材料的电导率取决于所施加的电压。这种行为是由复合材料中掺入的相邻碳纳米颗粒之间非理想的接触引起的。这种接触的电阻强烈地依赖于电场强度，因此也依赖于相邻纳米颗粒之间的距离。本文考虑了上述两种类型的碳纳米复合材料的非线性、非欧姆行为的实验。已经提出了一种基于电子隧穿通过电场形成的势垒的准经典方法的此类行为的模型描述。计算结果与现有实验数据定性相符。
