In the course of experiments to perform deprotonation and carbonization of doped polyaniline (PANI) nanotubes (NTs) by irradiating directly 2.45 GHz microwave (MW) in our microwave heating system (MWHS), we have discovered that the PANI-NTs self heat by absorbing the MW, but the temperature of the PANI-NTs stops rising around 300 °C in spite of the heightened MW power. Furthermore, we have found that the MW irradiated PANI-NTs have transferred from electrical conductor to insulator depending on the temperature of the PANI-NTs. By measuring electron spin resonance (ESR) spectra of the MW heated PANI-NTs, the existence of the unpaired electrons is shown to have a strong correlation between the degree of MW absorption and the transition in the electrical conductivities. In order to deprotonate and carbonize further the PANI-NTs, we have performed heat treatment for the PANI-NTs up to a temperature (T) of about 1200 °C in the same MWHS using carbon fiber which self heats by absorbing MW. The chemical transformations in the PANI-NTs induced by the heat treatments are discussed by measuring the X-ray photoelectron spectroscopy (XPS) spectra. Finally, the temperature dependence of electrical conductivities of the PANI-NTs are measured in order to investigate the mechanism of electrical conduction of the heat treated PANI-NTs.

中文翻译：

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微波加热聚苯胺纳米管的电导率及材料吸收微波的可能机制

在我们的微波加热系统 (MWHS) 中通过直接照射 2.45 GHz 微波 (MW) 对掺杂聚苯胺 (PANI) 纳米管 (NT) 进行去质子化和碳化的实验过程中，我们发现 PANI-NT 通过吸收MW，但尽管提高了 MW 功率，但 PANI-NT 的温度在 300 °C 左右停止上升。此外，我们发现 MW 辐照的 PANI-NTs 已经从电导体转移到绝缘体，这取决于 PANI-NTs 的温度。通过测量 MW 加热的 PANI-NT 的电子自旋共振 (ESR) 光谱，显示未配对电子的存在与 MW 吸收程度和电导率转变之间具有很强的相关性。为了进一步去质子化和碳化 PANI-NT，我们已经使用碳纤维在相同的 MWHS 中对 PANI-NT 进行了高达约 1200°C 的热处理，该碳纤维通过吸收 MW 进行自加热。通过测量 X 射线光电子能谱 (XPS) 光谱讨论了由热处理引起的 PANI-NT 中的化学转变。最后，测量了 PANI-NTs 的电导率的温度依赖性，以研究经过热处理的 PANI-NTs 的导电机制。