Electrical, magnetic, and structural properties of lithium salt doped polyaniline

We report the results of temperature dependence of dc conductivity σ_dc(T), electron paramagnetic resonance (EPR), and X-ray photoelectron spectroscopy (XPS) experiments for the polyaniline (PAN) doped with various lithium (Li) salts such as LiPF₆, LiBF₄, LiClO₄, LiAsF₆, and LiCF₃SO₃. A quasi one-dimensional (1D) variable range hopping (VRH) model provide the best fitting for σ_dc(T) the Li salt doped PAN samples, which is similar to that of protonic acid (HCl) doped polyaniline samples. The σ_dc and its temperature dependence vary with the kind of Li salts used. Temperature dependence of thermoelectric power of PAN doped with LiPF₆ shows the metallic behavior. From EPR experiments, we obtain that χ^P depends on the kind of Li salts. The results of XPS experiments are discussed to account for the doping procedure with Li salts. Temperature dependence of EPR linewidths and X-ray diffraction patterns are compared for the various Li salt doped PAN samples. The insulator-metal transition of PAN-LiPF₆ samples is also discussed.