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S.K. Chatterjee

Bio: S.K. Chatterjee is an academic researcher from Indian Association for the Cultivation of Science. The author has contributed to research in topics: Electrical resistivity and conductivity & Physics. The author has an hindex of 16, co-authored 83 publications receiving 925 citations.


Papers
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TL;DR: In this paper, the dc and ac conductivities of polyaniline and polyvinyl alcohol (PVA) blends have been reported from room temperature to 80 K in the frequency range of 1.8 kHz to 5.5 kHz.

192 citations

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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 article, the temperature dependence of resistivity for both PANI and PANI-MC has been analyzed by three-dimensional variable range hopping (VRH) type of conduction.
Abstract: Electrical resistance and magnetoresistance of the HCl doped polyaniline (PANI) in aqueous ethanol medium and polyaniline–methyl cellulose dispersion (PANI–MC) has been investigated at low temperature down to 1.8 K and in magnetic field up to 8 T. The weaker temperature dependence of resistivity characterized by the resistivity ratio ρr=ρ(1.8 K)/ρ(300 K) indicates that a better homogeneity and less disorder can be obtained by protonation with HCl in ethanol media. The temperature dependence of resistivity for both PANI and PANI–MC has been analyzed by three-dimensional variable range hopping (VRH) type of conduction. The samples with the resistivity ratio lying in the range of 102⩽ρr⩽103 exhibit a crossover from Mott to Efros–Shklovskii VRH conduction below 10 K. A large positive magnetoresistance at low temperature has been obtained.

50 citations

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TL;DR: In this paper, the electrical resistivity of titanium nitride thin films prepared by ion beam-assisted deposition technique in the temperature range 77⩽T ⩽300 K was reported.
Abstract: We report the electrical resistivity of titanium nitride thin films prepared by ion beam-assisted deposition technique in the temperature range 77⩽T⩽300 K. The residual resistivity (ρ0) of the films decreases by increasing nitrogen partial pressure. The films show the quadratic temperature behavior of resistivity in the investigated temperature range. Attempt has been made to explain such anomalous behavior by using existing theories.

35 citations

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TL;DR: The results of a comprehensive study of localization and electron-electron interaction effects in doped polypyrrole films show the conductivity when temperature T>10 K can be explained by Mott's variable-range hopping model and the density of states and hopping distance can be calculated from these data.
Abstract: We report the results of a comprehensive study of localization and electron-electron interaction effects in doped polypyrrole films. We have measured the electrical conductivity and magnetoconductivity within the temperature range 1.8 K≤T≤300 K. The observed temperature dependence of dc conductivity cannot be explained either by the band-conduction model or by assuming a temperature-dependent energy gap. However, the conductivity when temperature T>10 K can be explained by Mott's variable-range hopping model and the density of states and hopping distance can be calculated from these data

33 citations


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TL;DR: In this article, a review of the properties of the Al x Ga1−x As/GaAs heterostructure system is presented, which can be classified into sixteen groups: (1) lattice constant and crystal density, (2) melting point, (3) thermal expansion coefficient, (4), lattice dynamic properties, (5) lattices thermal properties,(6) electronic-band structure, (7) external perturbation effects on the bandgap energy, (8) effective mass, (9) deformation potential, (10) static and
Abstract: The Al x Ga1−x As/GaAs heterostructure system is potentially useful material for high‐speed digital, high‐frequency microwave, and electro‐optic device applications Even though the basic Al x Ga1−x As/GaAs heterostructure concepts are understood at this time, some practical device parameters in this system have been hampered by a lack of definite knowledge of many material parameters Recently, Blakemore has presented numerical and graphical information about many of the physical and electronic properties of GaAs [J S Blakemore, J Appl Phys 5 3, R123 (1982)] The purpose of this review is (i) to obtain and clarify all the various material parameters of Al x Ga1−x As alloy from a systematic point of view, and (ii) to present key properties of the material parameters for a variety of research works and device applications A complete set of material parameters are considered in this review for GaAs, AlAs, and Al x Ga1−x As alloys The model used is based on an interpolation scheme and, therefore, necessitates known values of the parameters for the related binaries (GaAs and AlAs) The material parameters and properties considered in the present review can be classified into sixteen groups: (1) lattice constant and crystal density, (2) melting point, (3) thermal expansion coefficient, (4) lattice dynamic properties, (5) lattice thermal properties, (6) electronic‐band structure, (7) external perturbation effects on the band‐gap energy, (8) effective mass, (9) deformation potential, (10) static and high‐frequency dielectric constants, (11) magnetic susceptibility, (12) piezoelectric constant, (13) Frohlich coupling parameter, (14) electron transport properties, (15) optical properties, and (16) photoelastic properties Of particular interest is the deviation of material parameters from linearity with respect to the AlAs mole fraction x Some material parameters, such as lattice constant, crystal density, thermal expansion coefficient, dielectric constant, and elastic constant, obey Vegard’s rule well Other parameters, eg, electronic‐band energy, lattice vibration (phonon) energy, Debye temperature, and impurity ionization energy, exhibit quadratic dependence upon the AlAs mole fraction However, some kinds of the material parameters, eg, lattice thermal conductivity, exhibit very strong nonlinearity with respect to x, which arises from the effects of alloy disorder It is found that the present model provides generally acceptable parameters in good agreement with the existing experimental data A detailed discussion is also given of the acceptability of such interpolated parameters from an aspect of solid‐state physics Key properties of the material parameters for use in research work and a variety of Al x Ga1−x As/GaAs device applications are also discussed in detail

2,671 citations

Journal ArticleDOI
TL;DR: The magnetocaloric effect and its most straightforward application, magnetic refrigeration, are topics of current interest due to the potential improvement of energy efficiency of cooling and temperature control systems, in combination with other environmental benefits associated to a technology that does not rely on the compression/expansion of harmful gases.

941 citations

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TL;DR: In this paper, phase transitions and structural and magnetic properties of rapidly solidified Ni50Mn38Sn12 alloy ribbons have been studied and the coercivity values measured in both temperature intervals suggest a significant difference in the behavior of the two materials.
Abstract: Phase transitions and structural and magnetic properties of rapidly solidified Ni50Mn38Sn12 alloy ribbons have been studied. Ribbon samples crystallize as a single-phase, ten-layered modulated (10M) monoclinic martensite with a columnar-grain microstructure and a magnetic transition temperature of 308 K. By decreasing the temperature, martensite undergoes an intermartensitic phase transition around 195 K. Above room temperature, the high temperature martensite transforms into austenite. Below 100 K, magnetization hysteresis loops shift along the negative H-axis direction, confirming the occurrence of an exchange bias effect. On heating, the thermal dependence of the coercive field HC shows a continuous increase, reaching a maximum value of 1017 Oe around 50 K. Above this temperature, HC declines to zero around 195 K. But above this temperature, it increases again up to 20 Oe falling to zero close to 308 K. The coercivity values measured in both temperature intervals suggest a significant difference in the...

940 citations

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840 citations

Journal ArticleDOI
TL;DR: In this article, alternating current and direct current (DC) conductivities have been measured in polymer-nanotube composite thin films for a range of concentrations of multi-wall nanotubes in two polymer hosts.
Abstract: Alternating current (ac) and direct current (dc) conductivities have been measured in polymer-nanotube composite thin films. This was carried out for a range of concentrations of multiwall nanotubes in two polymer hosts, poly(m-phenylenevinylene-co-2,5-dioctyloxyp-phenylenevinylene) (PmPV) and polyvinylalcohol (PVA). In all cases the dc conductivity σDC was ohmic in the voltage range studied. In general the ac conductivity displayed two distinct regions, a frequency independent region of magnitude σ0 at low frequency and a frequency dependent region at higher frequency. Both σDC and σ0 followed a percolation scaling law of the form σ∝(p−pc)t with pc=0.055% by mass and t=1.36. This extrapolates to a conductivity of 1×10−3 S/m for 100% nanotube content. Such a low value reflects the presence of a thick polymer coating, resulting in poor electrical connection between tubes. This leads to the suggestion that charge transport is controlled by fluctuation induced tunneling. In the high frequency regime the cond...

748 citations