Murshidābād, India
Murshidābād, India

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Das S.,Amity University | Das S.,Jadavpur University | Roychowdhury A.,Krishnath College | Das D.,UGC-DAE Consortium for Scientific Research | Sutradhar S.,Amity University
Journal of Alloys and Compounds | Year: 2017

Nanoparticles of Gd3+ ions doped ZnO were prepared by hydrothermal method. To obtain the desired nanocrystalline phase and also, to enhance the oxygen vacancy inside the host ZnO nanoparticles, the as prepared sample is sintered at 400 and 600 °C for 2 h in vacuum atmosphere. X-ray diffractograms (XRD) analysis reveals the absence of any impure phases in the Gd3+ ions doped ZnO nanostructure. The presence of intrinsic defects/oxygen vacancies were confirmed by the analysis of UV–Visible, PL and Raman spectra of the doped sample. The qualitative and quantitative analysis of intrinsic defects was successfully explained by three-state trapping model using positron annihilation study. Room temperature ferromagnetism was found in the sample of 5% Gd3+ ions doped ZnO, which has been successfully explained by the vacancy assisted bound magnetic polaron model. Frequencies as well as temperature dependent dielectric constant of the samples were investigated. The dielectric constants were recorded at 40 Hz and 100 kHz frequencies and the values are nearly ∼2.76 х 106 and 12782 respectively, in the 5% Gd3+ ions doped ZnO sample. © 2017 Elsevier B.V.

Roychowdhury A.,UGC-DAE Consortium for Scientific Research | Roychowdhury A.,Krishnath College | Das D.,UGC-DAE Consortium for Scientific Research
Materials Research Bulletin | Year: 2016

Reduced graphene oxide/α-Fe2O3 nanocomposites were synthesized by a simple sol-gel method. Initially, the samples were investigated by X-ray diffraction, high resolution transmission electron microscopy and Raman spectroscopy. High resolution transmission electron micrographs indicate that the magnetic nanoparticles are well dispersed in the reduced graphene oxide sheet-like structure. Fourier transform infrared spectroscopy studies corroborate the results obtained by X-ray diffraction. Temperature as well as field dependent magnetic measurements revealed ferromagnetism in the pristine α-Fe2O3 as well as in the nanocomposite sample that is attributed to surface canted spins and defects present in the samples. The enhanced value of coercivity in case of the nanocomposite sample could be ascribed to the Ruderman-Kittel-Kasuya-Yosida type of interaction between the isolated reduced graphene oxide spin and the magnetic ions. Presence of super paramagnetic doublet as well as sextet patterns related to hematite phase is confirmed by the 57Fe-Mössbauer spectroscopy. © 2015 Elsevier Ltd.

De A.,Krishnath College | Kundu S.,Indian Central Glass and Ceramic Research Institute
Journal of Materials Engineering and Performance | Year: 2016

Cd-Sn oxide nanocomposites were synthesized by sol-gel method from precursor sol containing Cd:Sn = 2:1 and 1:1 mol ratio. Instead of coprecipitation, a simple novel gel calcination route was followed. Cd (NO3)2. 4H2O and SnCl4. 5H2O were used as starting materials. Gel was calcined at 1050 °C for 2 h to obtain nanocomposites. XRD analysis reveals the presence of orthorhombic, cubic Cd2SnO4 along with orthorhombic, hexagonal CdSnO3 phases in both the composites. SEM and TEM studies indicate the development of nanocomposites of different shapes suggesting different degrees of polymerization in precursor sol of different composition. UV-Vis absorption spectra show a blue shift for both the composites compared to bulk values. Decrease of polarization with frequency, dipole contribution to the polarization, and more sensitivity to ethanol vapor were observed for the nanocomposite derived from precursor sol containing Cd:Sn = 2:1 mol ratio. © 2016, ASM International.

de A.,Krishnath College | Antony G.,Indian Central Glass and Ceramic Research Institute | Antony G.,Cochin University of Science and Technology | Kundu S.,Indian Central Glass and Ceramic Research Institute
Journal of Materials Science: Materials in Electronics | Year: 2016

Cd–Sn oxide nanocomposite powders were synthesized by a facile gel calcination method, starting from precursor sol having Cd:Sn ratio as 2:1. The powders were characterized in terms of their phase formation behaviour and morphological features using X-ray diffractometer, FTIR, UV–visible spectra and FESEM analyses. Sensor fabricated from nanocomposite calcined at 1050 °C exhibited excellent ethanol sensing performance, ~86 % for 50 ppm ethanol vapour. It also revealed quite a good sensitivity at concentration down to 5 ppm vapour. Sensors were quite stable and selective towards ethanol vapour. A possible mechanism for enhanced performance due to formation of preferential perovskite cadmium stannite phase has been discussed. © 2016 Springer Science+Business Media New York

Bagchi B.,University of Calcutta | Banerjee A.,Krishnath College | Mandal P.,University of Calcutta
International Journal of Modern Physics A | Year: 2015

We study a generalized scheme of Swanson Hamiltonian from a second-derivative pseudo-supersymmetric approach. We discuss plausible choices of the underlying quasi-Hamiltonian and consider the viability of applications to systems like the isotonic oscillator and CPRS potential. © 2015 World Scientific Publishing Company.

Bagchi B.,University of Calcutta | Banerjee A.,Krishnath College
Journal of Physics A: Mathematical and Theoretical | Year: 2015

We investigate bicomplex Hamiltonian systems in the framework of an analogous version of the Schrodinger equation. Since in such a setting three different types of conjugates of bicomplex numbers appear, each is found to define, in a natural way, a separate class of time reversal operator. However, the induced parity (P)-time (T)-symmetric models turn out to be mutually incompatible, except for two of them which could be chosen uniquely. The latter models are then explored by working within an extended phase space. Applications to the problems of harmonic oscillator, inverted oscillator and isotonic oscillator are considered and many new interesting properties are uncovered for the new types of PT symmetries. © 2015 IOP Publishing Ltd.

Das S.K.,Krishnath College | Karmakar S.N.,Krishnath College
International Journal of Physiology, Pathophysiology and Pharmacology | Year: 2015

Green tea leaf extract (GTLE), used in this experiment has shown great influence on male reproductive system functionally as well as morphologically. The extract was prepared according to the method of Wei. H. et al. The extract was given to two different experimental animal groups with two different doses during 26 consecutive days. After treatment it was found that, the weight of the testis was markedly reduced instead of normal weight gain of all the animals. The sperm count and motility were reduced for the treated groups as compared with control animal group. The enzymes like SGPT and SGOT were as usual and other blood parameters like glucose and protein were also as usual comparing with controlled group. Testosterone level was reduced in the treated groups. FSH and LH levels were also altered accordingly in treated groups. Histological examination showed inhibition of spermatogenesis as evidenced by disintegration of seminiferous tubules of testis. Result of this study showed that GTLE has potent castrative effect on male reproductive system in dose dependent manner. © 2015, E-Century Publishing Corporation. All rights reserved.

Sarkar P.,Visva Bharati University | Ahamed B.,Visva Bharati University | Ahamed B.,Krishnath College
International Journal of Quantum Chemistry | Year: 2011

The Fourier grid Hamiltonian method for calculating vibrational energy levels of triatomic molecules is presented. We have used direct product basis functions obtained from the Fourier grid Hamiltonian method for one-dimensional Schrödinger equation for radial coordinates and the associated Legendre polynomial for angular coordinate. The resulting matrix is diagonalized by using Lanczos method. The method is tested for the calculation of vibrational energy levels of H2O and MgH2 molecules. Copyright © 2010 Wiley Periodicals, Inc.

The photodissociation dynamics of a triatomic molecule in the presence of pulsed and bichromatic electric field have been investigated. We have considered MgH2 molecule in its ground state potential energy surface. The time-dependent Fourier Grid Hamiltonian method is invoked to follow the dissociation dynamics as a function of field strength, frequency, phase difference, etc. © 2013 Taylor and Francis.

De A.,Krishnath College
Transactions on Electrical and Electronic Materials | Year: 2015

Optical and electrical properties were studied for Antimony doped tin oxide thin films from precursors containing 10, 30, 50, and 70 atom% of Sb deposited on bare sodalime silica, barrier layer coated sodalime silica, and pure silica glass substrates by sol-gel spinning technique. The direct band gaps were found to vary from 3.13~4.12 eV when measured in the hv range of 2.5~5.0 eV, and varied from 4.22~5.08 eV when measured in the range of 4.0~7.0 eV. Indirect band gap values were in the range of 2.35~3.11 eV. Blue shift of band gap with respect to bulk band gap and Moss-Burstein shift were observed. Physical thickness of the films decreased with the increase in % Sb. Resistivity of the films deposited on SLS substrate was in the order of 10-2 ohm cm. Sheet resistance of the films deposited on barrier layer coated soda lime silica glass substrate was found to be relatively less. ©2015 KIEEME. All rights reserved.

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