Effect of multiwall carbon nanotubes on electrical and structural properties of polyaniline

Polyaniline (PANI) and PANI/CNT (multiwall carbon nanotubes, CNT) composites were prepared using an oxidative chemical polymerization method with ammonium persulfate and dodecyl benzene sulfonic acid as the oxidizing agent and surfactant, respectively. Fourier-transform infrared spectroscopy spectra illustrate the presence of PANI in the composite and show that some interaction exists between PANI and CNT. Embedding of CNT in the PANI matrix is confirmed by scanning electron micrography. Conductivity of the PANI/CNT composites was higher than that of pure PANI, and the maximum conductivity obtained was 4.44 S/cm at 20 wt. CNT

La<SUB>1−x</SUB>Ce<SUB>x</SUB>CrO<SUB>3</SUB> (0.0 ≤x≤ 1.0): a new series of solid solutions with tunable magnetic and optical properties

A new series of La1−xCexCrO3 (0.0 ≤ x ≤1.0) compounds in nanocrystalline form were synthesized using a two-step synthesis route, involving an initial combustion reaction followed by vacuum heating in the presence of a Zr sponge, which acted as an oxygen getter. For the first time, a homogeneous solid solution formation throughout the entire range was obtained in this series. These compounds were characterized using X-ray diffraction, diffuse reflectance UV visible spectrophotometry, and superconducting quantum interference device magnetometry. The crystallite size for the phase-pure products was confirmed to be ∼42−44 nm by high-resolution transmission electron microscopy. All compounds (nanocrystalline) in this series are found to be predominantly antiferromagnetic in nature with a remarkable linear increasing trend in Neel temperature from 257 to 281.5 K as a function of decreasing Ce3+ content. Interestingly, the band gap also shows a linear decrease from 3.21 to 3.02 eV as a function of increasing Ce3+ concentration in the La1−xCexCrO3 series

Electrical, structural and magnetic properties of polyaniline/pTSA-TiO2 nanocomposites

Polyaniline (PANI)/para-toluene sulfonic acid (pTSA) and PANI/pTSA-TiO2 composites were prepared using chemical method and characterized by infrared spectroscopy (IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM). The electrical conductivity and magnetic properties were also measured. In corroboration with XRD, the micrographs of SEM indicated the homogeneous dispersion of TiO nanoparticles in bulk PANI/pTSA matrix. Conductivity of the PANI/pTSA-TiO2 was higher than the PAN[/pTSA, and the maximum conductivity obtained was 9.48 (S/cm) at 5 wt% of TiO2. Using SQUID magnetometer, it was found that PANI/pTSA was either paramagnetic or weakly ferromagnetic from 300 K down to 5 K with H-C approximate to 30 Oe and M-r approximate to 0.015 emu/g. On the other hand,PANI/pTSA-TiO2 was diamagnetic from 300 K down to about 50 K and below which it was weakly ferromagnetic. Furthermore, a nearly temperature-independent magnetization was observed in both the cases down to 50 K and below which the magnetization increased rapidly (a Curie like susceptibility was observed). The Pauli susceptibility (chi(pauli)) was calculated to be about 4.8 X 10(-5) and 1.6 x 10(-5)emug(-1) Oe(-1) K for PANI/pTSA and PANI/pTSA-TiO2, respectively