Electrical resistivity and magnetoresistivity of protonic acid (h2SO4 and HCl)-doped polyaniline at low temperature

Abstract

Electrical-transport properties of protonic acid (H 2 SO 4 and HCl)-doped polyaniline (PANI) in an aqueous ethanol medium were investigated in the temperature range 1.8 K Յ T Յ 300 K and in a magnetic field up to 8 T. The room-temperature resistivity of HCl-doped PANI is larger than that of H 2 SO 4 -doped PANI. The resistivity ratios r ϭ (1.8 K)/(300 K) of the samples are high. The samples in the insulating region show a crossover from a Mott to an Efros-Shklovskii variable range hopping conduction at T ϭ 9.8 K for H 2 SO 4 -doped PANI and 8.5 K for HCl-doped PANI. The magnetoresistivity of these samples is also explained by the variable range hopping theory. The different physical parameters were calculated from the experimental data.

Electron transport properties of cobalt doped polyaniline

“…The dc resistivity of different PANI-Co samples has been measured in the temperature range of 77 T 300 K. The room temperature resistivity ρ(300 K) of the investigated PANI-Co samples varies between 0.013 and 0.061 cm and is listed in table 1. In our previous study [32], it was observed that room temperature resistivity of PANI-HCl is 0.080 cm and that of PANI-H 2 SO 4 is 0.105 cm. So the introduction of Co atoms within PANI only slightly reduces its resistivity.…”

“…They have studied the effect of ZnCl 2 on the transport properties of PANI-HCl. Ghosh et al [32] have studied the electron transport properties of HCl doped PANI. They observed a transition from 3D Mott (T 1/4 ) to Efros-Shoklovskii (T 1/2 ) in the temperature dependent conductivity at 10 K. Lu et al [33] have studied the hysteresis loop at room temperature of PANI-Fe 3 O 4 nanoparticles.…”

Electrical‐transport properties of iodine‐doped conducting polyaniline

“…Figure 4 shows the variation of magnetoconductivity with magnetic field of different samples at 200 K. All of the samples showed positive magnetoconductivity, whereas the HCl‐ and H 2 SO 4 ‐doped PANI showed negative magnetoconductivity 23. According to VRH theory, conductivity in the presence of a magnetic field can be explained by two mechanisms, such as the wave function shrinkage model51–55 and orbital magnetoconductivity theory 56–58.…”

“…Pure polymers can be classified as insulating or noncrystalline semiconducting materials with very low charge carrier mobilities. Doping renders it a good conductor due to the delocalization of charge and spin along the backbone of the polymer 15–25. The electrical conductivity of PANI is affected most by doping and medium, and many investigations have been carried out on doped PANI during the last few decades.…”

“…Kahol and coworkers26, 27 argued that quasi one‐dimensional (1D) variable range hopping (VRH) was responsible for conduction in doped PANI, whereas Sanjai et al28 observed three‐dimensional (3D) VRH conduction in unblended PANI but 1D VRH for blended PANI. Ghosh et al23 claimed a transition from 3D VRH Mott to Efros‐Shoklovskii at low temperatures. Wang and coworkers29, 30 were of the opinion that 1D conduction is important for the system with conducting chains totally isolated, but if the bundles are coupled, the 1D VRH conduction is not valid.…”