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Ajit Kumar Meikap

Bio: Ajit Kumar Meikap is an academic researcher from National Institute of Technology, Durgapur. The author has contributed to research in topics: Dielectric & Nanocomposite. The author has an hindex of 23, co-authored 169 publications receiving 1699 citations. Previous affiliations of Ajit Kumar Meikap include Indian Association for the Cultivation of Science.


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors performed morphological, structural, thermal and optical characterization of polyaniline-silver nanocomposite and found that the electrical conductivity increases with an increase in the number of nanoparticles.

189 citations

Journal ArticleDOI
TL;DR: In this article, the authors measured the electrical conductivity of HCl doped conducting polyaniline in the presence as well as in the absence of a magnetic field in the temperature range 1.8 K≤ T ≤ 300 K.

75 citations

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TL;DR: In this paper, a comparative study on the dielectric relaxation and ac conductivity behavior of pure polyvinyl alcohol (PVA) and PVA?mercury selenide (HgSe) quantum dot hybrid films in the temperature range 298?K???T???420?K and in the frequency range 100?Hz???f???1?MHz was performed.
Abstract: Here we report a comparative study on the dielectric relaxation and ac conductivity behaviour of pure polyvinyl alcohol (PVA) and PVA?mercury selenide (HgSe) quantum dot hybrid films in the temperature range 298?K???T???420?K and in the frequency range 100?Hz???f???1?MHz. The prepared nanocomposite exhibits a larger dielectric constant as compared to the pure PVA. The real and imaginary parts of the dielectric constants were found to fit appreciably with the modified Cole?Cole equation, from which temperature-dependent values of the relaxation times, free charge carrier conductivity and space charge carrier conductivity were calculated. The relaxation time decreases with the quantum dot's inclusion in the PVA matrix and with an increase in temperature, whereas free charge carrier conductivity and space charge carrier conductivity increases with an increase in temperature. An increase in ac conductivity for the nanocomposites has also been observed, while the charge transport mechanism was found to follow the correlated barrier hopping model in both cases. An easy-path model with a suitable electrical equivalent circuit has been employed to analyse the temperature-dependent impedance spectra. The imaginary part of the complex electric modulus spectra exhibit an asymmetric nature and a non-Debye type of behaviour, which has been elucidated considering a generalized susceptibility function. The electric modulus spectra of the nanocomposite demonstrate a smaller amplitude and broader width, as compared to the pure PVA sample.

53 citations

Journal ArticleDOI
TL;DR: An in situ chemical polymerization method was applied in order to prepare polyaniline-multiwalled carbon nanotube (PANI-MWCNT) composites with different concentrations of MWCNT as mentioned in this paper.
Abstract: An in situ chemical polymerization method was applied in order to prepare polyaniline-multiwalled carbon nanotube (PANI-MWCNT) composites with different concentrations of MWCNT. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, optical absorption and photoluminescence analyses of the composites were performed to investigate the structural, morphological and optical properties of the composites. Electrical transport properties of different PANI-MWCNT composites were investigated in the temperature range 77?K ? T??? 300?K in the presence and also in the absence of a magnetic field up to 1?T. The dc resistivity of the composites follows Mott's variable range hopping theory. Two different slopes have been observed in temperature variation of resistivity, which occurs due to the presence of MWCNT in the polymer matrix. The magnetoconductivity of the samples at different temperatures is negative, which can be explained by the wavefunction shrinkage effect.

53 citations

Journal ArticleDOI
TL;DR: In this article, the dc resistivity and magnetoresistivity of cobalt doped polyaniline in an aqueous ethanol medium were investigated in the temperature range 77 ≤ T ≤ 300 K, applying magnetic fields up to 1
Abstract: Electrical transport properties of cobalt doped polyaniline in an aqueous ethanol medium were investigated in the temperature range 77 ≤ T ≤ 300 K, applying magnetic fields up to 1 T in the frequency range 20 Hz–1 MHz. The room temperature dc resistivity increases with increase in Co content. The dc resistivity and magnetoresistivity of these samples have been interpreted in terms of the variable range hopping theory. The frequency dependence of conductivity has been described by a power law σ(ω) ∝ ωS. The value of s is found to be temperature dependent, which shows a decreasing trend with temperature. The correlated barrier hopping model is the most likely mechanism for the electron transport. The different physical parameters were calculated from the experimental data.

52 citations


Cited by
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Journal ArticleDOI
01 Oct 1971-Nature
TL;DR: Lipson and Steeple as mentioned in this paper interpreted X-ray powder diffraction patterns and found that powder-diffraction patterns can be represented by a set of 3-dimensional planes.
Abstract: Interpretation of X-ray Powder Diffraction Patterns . By H. Lipson and H. Steeple. Pp. viii + 335 + 3 plates. (Mac-millan: London; St Martins Press: New York, May 1970.) £4.

1,867 citations

Journal ArticleDOI
TL;DR: A detailed discussion on the mechanism of electrical conduction in PANI and the factors those influence the conductivity of PANI is also included in this paper, where the problems of effective utilization and the methods adopted to overcome these problems are also provided.

1,632 citations

Journal ArticleDOI
TL;DR: This Review presents a comprehensive review of the use of ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications.
Abstract: Dielectric polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. In this Review, we present a comprehensive review of the use of ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications. Various parameters like dielectric constant, dielectric loss, breakdown strength, energy density, and flexibility of the polymer nanocomposites have been thoroughly investigated. Fillers with different shapes have been found to cause significant variation in the physical and electrical properties. Generally, one-dimensional and two-dimensional nanofillers with large aspect ratios provide enhanced flexibility versus zero-dimensional fillers. Surface modification of nanomaterials as well as polymers adds flavor to the dielectric properties of the resulting nanocomposites. Nowadays, three-phase nanocomposites with either combination of fillers...

1,143 citations

Journal ArticleDOI
TL;DR: A green chemistry method for synthesized colloidal silver nanoparticles (Ag NPs) in polymeric media using silver nitrate, polyethylene glycol, and β-D-glucose as a silver precursor, stabilizer, and reducing agent is reported.
Abstract: The roles of green chemistry in nanotechnology and nanoscience fields are very significant in the synthesis of diverse nanomaterials. Herein, we report a green chemistry method for synthesized colloidal silver nanoparticles (Ag NPs) in polymeric media. The colloidal Ag NPs were synthesized in an aqueous solution using silver nitrate, polyethylene glycol (PEG), and β-D-glucose as a silver precursor, stabilizer, and reducing agent, respectively. The properties of synthesized colloidal Ag NPs were studied at different reaction times. The ultraviolet-visible spectra were in excellent agreement with the obtained nanostructure studies performed by transmission electron microscopy (TEM) and their size distributions. The Ag NPs were characterized by utilizing X-ray diffraction (XRD), zeta potential measurements and Fourier transform infrared (FT-IR). The use of green chemistry reagents, such as glucose, provides green and economic features to this work.

434 citations

Journal ArticleDOI
01 Jan 2008-ACS Nano
TL;DR: A unique nanostructured polyaniline (PANI)/mesoporous TiO(2) composite was synthesized and explored as an anode in Escherichia coli microbial fuel cells and has great potential to be used as the anode for a high-power MFC and may also provide a new universal approach for improving different types of MFCs.
Abstract: A unique nanostructured polyaniline (PANI)/mesoporous TiO(2) composite was synthesized and explored as an anode in Escherichia coli microbial fuel cells (MFCs). The results of X-ray diffraction, morphology, and nitrogen adsorption-desorption studies demonstrate a networked nanostructure with uniform nanopore distribution and high specific surface area of the composite. The composite MFC anode was fabricated and its catalytic behavior investigated. Optimization of the anode shows that the composite with 30 wt % PANI gives the best bio- and electrocatalytic performance. A possible mechanism to explain the excellent performance is proposed. In comparison to previously reported work with E. coli MFCs, the composite anode delivers 2-fold higher power density (1495 mW/m(2)). Thus, it has great potential to be used as the anode for a high-power MFC and may also provide a new universal approach for improving different types of MFCs.

382 citations