The study of electrical and magnetic properties of LiPF6 doped polyaniline

The results of temperature dependent de conductivity, EPR magnetic suscepti bility, 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-Li PF6 samples vary with the average molecular weight (Mw) of polyaniline used and the composition of doping solution. The EPR linewidth and Pauli suscep tibility (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 intermediat e Mw PAN samples. Based on the results of XPS and EPR experiments, some por tions of quinoid rings in emeraldine base form of PAN are transformed into benzenoid rings through LiPF6 doping process, indicating the formation of p olarons. However, the existence of some portions of quinoid rings in PAN-Li PF6 samples after doping suggests an inhomogeneous doping or a pseudo dopin g. (C) 1999 Elsevier Science S.A. All rights reserved.