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首页> 外文期刊>Synthetic Metals >Variable-range-hopping exponents 1/2, 2/5 and 1/4 in HCl-doped polyaniline pellets
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Variable-range-hopping exponents 1/2, 2/5 and 1/4 in HCl-doped polyaniline pellets

机译：HCl掺杂的聚苯胺颗粒中的变程跳跃指数1 / 2、2 / 5和1/4

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摘要

We study the variable-range-hopping (VRH) charge transport in polyaniline pellets doped with HCl over a wide range. Increase of the doping not only enhances the electrical conductivity sigma but also weakens the disorder, which affects the VRH mechanism. This is revealed in the sigma vs temperature (T) characteristics sigma alpha exp[-(T_0/T)~(alpha)], where alpha and T_0 carry information on the underlying physics. Below approx 200 K, alpha undergoes a significant disorder dependent change at approx 60 percent of the full doping: alpha = 1/2 for lower doping, whereas more-doped samples exhibit alpha = 2/5. From approx 200 K up to room temperature, most of the samples (i.e., those doped below 80 percent) exhibit alpha = 1 /4 regardless of the corresponding alpha at low T. These results can be to a large extent explained by the VRH theory of Fogler et al. [MM. Fogler, S. Teber, B.I. Shklovskii, Phys. Rev. B 69 (2004) 035413] (FTS). In particular, alpha = 1/2, 2/5, 1/4 are therein anticipated for three-dimensional transport together with crossovers between these values in response to changes in disorder and/or T. The doping (disorder) dependence of T_0 for a given alpha = 1/2 or 2/5 also follows the FTS predictions reasonably well. The appearance of alpha = 1/4 at high T can be understood from an analysis of energy scales that are relevant to VRH as described by the FTS model.
机译：我们研究了在较宽范围内掺杂HCl的聚苯胺颗粒中的变程跳跃（VRH）电荷传输。掺杂的增加不仅增强了电导率σ，而且减弱了无序性，从而影响了VRH的机理。这可以通过西格玛与温度（T）特性西格玛alpha exp [-（T_0 / T）〜α]来揭示，其中alpha和T_0携带有关基础物理的信息。低于大约200 K，α会在完全掺杂的大约60％处发生与无序有关的显着变化：对于较低的掺杂，α= 1/2，而掺杂较多的样品则显示alpha = 2/5。从大约200 K到室温，大多数样品（即，掺杂浓度低于80％的样品）的α= 1/4，而与低T下的相应α无关。这些结果在很大程度上可以由VRH理论解释Fogler等人的论文。 [MM。福格勒（S. Shklovskii，物理学。 B 69（2004）035413]（FTS）。特别地，对于三维传输，期望其中α= 1 / 2、2 / 5、1 / 4，以及响应于无序和/或T的变化而在这些值之间的交叉。T_0的掺杂（无序）依赖性给定的alpha = 1/2或2/5也会很好地遵循FTS的预测。如FTS模型所描述的，从与VRH相关的能级分析可以理解高T下α= 1/4的出现。

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