The study of electrical and magnetic properties of LiPF6 doped polyaniline

The results of temperature dependent de conductivity, EPR magnetic susceptibility, and X-ray photoelectron spectroscopy experiments (XPS) are reported for polyaniline (PAN) doped with lithium hexafluorophosphate (LiPF6), PAN-LiPF6. DC conductivity (sigma(dc)) and its temperature dependence of PAN-LiPF6 samples vary with the average molecular weight (Mw) of polyaniline used and the composition of doping solution. The EPR linewidth and Pauli susceptibility (chi(P)) depend on the Mw of PAN used. The sigma(dc) and the chi(P) of the intermediate Mw PAN-LiPF6 samples are higher than those of the low Mw PAN samples, indicating more highly conducting state of the intermediate Mw PAN samples. Based on the results of XPS and EPR experiments, some portions of quinoid rings in emeraldine base form of PAN are transformed into benzenoid rings through LiPF6 doping process, indicating the formation of polarons. However, the existence of some portions of quinoid rings in PAN-LiPF6 samples after doping suggests an inhomogeneous doping or a pseudo doping. (C) 1999 Elsevier Science S.A. All rights reserved.