Faculty Publications
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Item Electrical and magnetic properties of chitosan-magnetite nanocomposites(2010) Bhatt, A.S.; Bhat, D.K.; Santosh, M.S.Magnetite powders in nanometer size have been synthesized by the hydrothermal process. Various magnetic films of chitosan and the synthesized magnetite nanopowders containing different concentrations of the latter were prepared by ultrasonication route. The X-ray diffraction (XRD) studies and the transmission electron microscopy (TEM) images showed that the synthesized magnetite particles had 80 nm dimensions. The band gap of the composites was evaluated using the UV-visible Spectroscopy. The influence of magnetite content on the magnetic properties of the composite showed a decrease in the saturation magnetization with the decrease in the magnetic content. The effect of magnetite content on the dielectric properties of the polymer film at different frequencies from 0.01 to 105 Hz was studied using an electrochemical impedance spectroscopy. The possible mechanism for the observed electrical properties of the composite films was discussed. © 2010 Elsevier B.V. All rights reserved.Item Electrochemical properties of chitosan-Co3O4 nanocomposite films(Elsevier B.V., 2011) Bhatt, A.S.; Bhat, D.K.; Santosh, M.S.Chitosan-Co3O4 composite films have been prepared by solution casting method. The obtained films have been characterised by XRD and FESEM. The electrical properties of the films are examined by impedance spectroscopy in the temperature range 303-343 K. The impedance plot of the films pronounces the role of temperature in charge-transfer resistance of the composite. Frequency as well as temperature dependencies of dielectric constant and dielectric loss exhibit the general trend followed by carrier dominated dielectrics. Electric modulus parameters give an insight on the ionic conductivity and relaxation phenomena of the composite films. The dielectric parameters along with modulus data have been exploited to discuss the conduction mechanism in the material. The minimum activation energy of 3.9 kJ mol -1 and maximum room temperature conductivity of 1.94 × 10 -2 S cm-1 were found for composite film with 8% Co 3O4 content. © 2011 Elsevier B.V. All rights reserved.Item Chitosan/NiO nanocomposites: A potential new dielectric material(2011) Bhatt, A.S.; Bhat, D.K.; Santosh, M.S.; Tai, C.-W.The study of electrochemical behavior of organic-inorganic nanocomposite materials remains a major challenge for application in energy storage devices. Here, new composite materials of chitosan and NiO nanoparticles have been fabricated. The NiO nanoparticles are well characterized by infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The electrical properties of the films are studied by impedance spectroscopy at different temperatures; and thereby permittivity, electric modulus and conductivity data are obtained. By studying the variations in permittivity and electric modulus spectra with respect to applied frequency signal and temperature, the ionic conductivity of the material is investigated. The Correlated Barrier Hopping model is employed to understand the conduction mechanism. An admirable conductivity of 1.4 × 10-2 S cm -1 is obtained for a nanocomposite with 4 wt% NiO content. The activation energies of the composite films decrease with increase in NiO content, from 16.5 to 4.8 kJ mol-1. © 2011 The Royal Society of Chemistry.