Puruliya, India
Puruliya, India

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Sabyasachi Sk.,Indian Association for The Cultivation of Science | Patra M.,Indian Association for The Cultivation of Science | Patra M.,Raghunathpur College | Majumdar S.,Indian Association for The Cultivation of Science | And 6 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

The charge ordered La 1/3Sr 2/3FeO 3-δ (LSFO) in bulk and nanocrystalline forms are investigated using ac and dc magnetization, Mössbauer, and polarized neutron studies. A complex scenario of short-range charge and magnetic ordering is realized from the polarized neutron studies in nanocrystalline specimen. This short-range ordering does not involve any change in spin state and modification in the charge disproportion between Fe3 + and Fe5 + compared to bulk counterpart as evident in the Mössbauer results. The refinement of magnetic diffraction peaks provides magnetic moments of Fe3 + and Fe5 + are about 3.15 μ B and 1.57μ B for bulk, and 2.7 μ B and 0.53μ B for nanocrystalline specimen, respectively. The destabilization of charge ordering leads to magnetic phase separation, giving rise to the robust exchange bias (EB) effect. Strikingly, EB field at 5 K attains a value as high as 4.4 kOe for average size ∼70 nm, which is zero for the bulk counterpart. A strong frequency dependence of ac susceptibility reveals cluster-glass-like transition around ∼65 K, below which EB appears. Overall results propose that finite-size effect directs the complex glassy magnetic behavior driven by unconventional short-range charge and magnetic ordering, and magnetic phase separation appears in nanocrystalline LSFO. © 2012 American Physical Society.


Patra M.,Raghunathpur College | Majumdar S.,Indian Association for The Cultivation of Science | Giri S.,Indian Association for The Cultivation of Science | Xiao Y.,Jülich Research Center | Chatterji T.,Laue Langevin Institute
Journal of Alloys and Compounds | Year: 2012

NdAl 2 and TmAl 2 single-crystals display Curie temperature (T C) at 76.5 and 6.0 K, which are significantly close to liquid nitrogen and helium (T He) temperatures, respectively. Maximum entropy-change (-ΔS M) for 0-70 kOe are 35.9 and 8.9 J/kg-K at T C with large cooling efficiency 655 and 398 J/kg for TmAl 2 and NdAl 2, respectively. Adiabatic temperature change at T He for 0-20 kOe is 3.7 K for TmAl 2. This is promising for cryogenic refrigeration down to sub-Kelvin temperature using an electromagnet. The -ΔS M for SmAl 2 is low (∼0.5 J/kg-K at T C for 0-70 kOe). The direction-dependent anisotropy in thermal and field variations of ΔS M, and a reasonable correlation between ΔS M and magnetoresistance are realized for NdAl 2 and TmAl 2. © 2012 Elsevier B.V. All rights reserved.


Patra M.,Raghunathpur College | Majumdar S.,Indian Association for The Cultivation of Science | Giri S.,Indian Association for The Cultivation of Science | Xiao Y.,Jülich Research Center | Chatterji T.,Laue Langevin Institute
Journal of Physics Condensed Matter | Year: 2014

We report the magnetization (M) and magnetoresistance (MR) results of HoAl2 single crystals oriented along the 100 and 110 directions. Although HoAl2 has cubic Laves phase structure, a large anisotropy is observed in M and MR below the Curie temperature (TC). A satisfactory correlation between magnetic entropy change (ΔSM) and MR could be established along 110 and also 100, except for the temperature (T) region around which spin reorientation takes place. Large inverse magnetocaloric effect is observed at low T, which is associated with the spin reorientation process in the 100 direction. A theoretical model based on the Landau theory of phase transition can describe the T-variation of -ΔS M for T > TC. © 2014 IOP Publishing Ltd.


Biswas B.,Raghunathpur College | Mitra P.,Indian Association for The Cultivation of Science | Ghosh R.,University of Burdwan
Journal of the Indian Chemical Society | Year: 2013

A mononuclear manganese(II) complex [Mn(phen)2(OH 2)2][Mn(phen)2(OH2)Cl](NO 3)3 (1) containing 1,10-phenanthroline [phen = 1,10-phenanthroline] ligand has been synthesized and crystallographically characterized. The oxidation level of the manganese atoms in two asymmetric units was determined by bond valence sum calculation (BVS). The DNA binding study has been explored by spectrophotometric and spectrofluorimetric measurements.


De B.,Moulana Azad College | Sau G.,Beramara Ramchandrapur High School | Biswas S.K.,West Kodalia Adarsha Siksha Sadan | Bhattacharyya S.,Indian Statistical Institute | Guptaroy P.,Raghunathpur College
International Journal of Modern Physics A | Year: 2010

The transverse momentum spectra of secondary η particles produced in P+P, D + Au and Au + Au interactions at √sNN = 200 GeV at different centralities have been studied in the light of a nonextensive thermodynamical approach. The results and the possible thermodynamical insights, thus obtained, about the hadronizing process have also been discussed in detail. © 2010 World Scientific Publishing Company.


Biswas B.,Raghunathpur College | Hung S.-P.,National Cheng Kung University | Tsai H.-L.,National Cheng Kung University | Ghosh R.,University of Burdwan | Kole N.,Raghunathpur College
Journal of Coordination Chemistry | Year: 2012

An organic-inorganic hybrid solid [(dpaH) +(NCS) -] (1) (dpa = 2,2'-dipyridylamine) based on an anionic template NCS - has been synthesized. Single crystal X-ray structural analysis reveals that NCS - templates assemble dpaH + units into a 3-D layer structure along the b axis through strong hydrogen bonding. Molecular salt 1 works as an anion-binder efficiently and selectively for recognition and sensing purposes in aprotic solvents. This receptor shows changes both in its UV-Vis absorption and fluorescence emission spectra upon the addition of F -, resulting in high selectivity for fluoride detection in CH 3CN. It is promising to use these systems in various sensing applications. © 2012 Taylor & Francis.


Dey D.,Raghunathpur College | Yadav H.R.,Indian Institute of Science | De A.,Raghunathpur College | Chatterjee S.,CSIR - Central Electrochemical Research Institute | And 4 more authors.
Journal of Coordination Chemistry | Year: 2015

A new one-dimensional (1-D) Pb(II) coordination polymer, [Pb(2,2′-bpy)(NO3)2(H2O)]n (1) (2,2′-bpy = 2,2′-bipyridine), has been synthesized and characterized by different spectroscopic techniques and X-ray single-crystal analysis. From the X-ray crystal structure of 1, the Pb2+ can be best described as a highly distorted pentagonal bipyramid with O4 (water) and O6 (nitrate) at apical positions (O4-Pb-O6 of 143.7(1)°). Variability in bond distances reveals that Pb2+ is unsymmetrically surrounded by two nitrates, one 2,2′-bpy and one water. Nitrates bridge between monomers. The molecule crystallizes in the monoclinic P21/n (14) space group. This is the first example of a 1-D Pb(II) polymer in which nitrates show three different coordination motifs (terminal, chelating, and bridging). Solid state as well as solution phase UV-vis spectral analysis and mass spectrometric studies clearly reveal instability with breakdown of Pb(II) polymer in aqueous solution. The arrangement of the 2,2′-bpy, water, and nitrates leaves a coordination gap at the Pb(II) occupied probably by a stereo-active lone pair of electrons. © 2014 Taylor & Francis.


Guptaroy P.,Raghunathpur College | Guptaroy S.,Basantidevi College
Chinese Physics Letters | Year: 2014

Experiments involving proton - proton collisions at energies √s NN = 0.9, 2.76 and 7 TeV in the large hadron collider produce a vast amount of high-precision data. In this work, we analyze two aspects of the measured data, viz., (i) the pT-spectra of pions, kaons, proton-antiproton at the above-mentioned energies, and (ii) some of their very important ratio behaviors, in the light of a version of the sequential chain model. The agreements between the measured data and the model-based results are generally found to be modestly satisfactory. © 2014 Chinese Physical Society and IOP Publishing Ltd.


Biswas B.,Raghunathpur College | Kole N.,Raghunathpur College | Patra M.,Raghunathpur College | Dutta S.,University of Burdwan | Ganguly M.,University of Burdwan
Journal of Chemical Sciences | Year: 2013

A trinuclear zinc(II) complex [Zn3L2(μ-O2CCH3)2(H2O)2]H2O2CH3OH (1) was synthesized from an in situ reaction between zinc acetate and a Schiff base ligand (H2L = 2-((2-hydroxyphenylimino) methyl)-6-methoxyphenol). The ligand was prepared by (1:1) condensation of ortho-vanillin and orthoaminophenol. The ligand and zinc(II) complex were characterized by elemental analysis, Fourier Transform Infrared (FTIR), 1H-Nuclear Magnetic Resonance (NMR), UV-Vis spectroscopy, Powder X-ray Diffraction (PXRD) and thermogravimetric analysis. 1 crystallizes in P-1 space group with a = 11.9241(3) Å, b = 12.19746 Å, c = 20.47784Å with unit cell volume is 2674.440 (Å)3. Binding property of the complex with calf thymus DNA (CT-DNA) has been investigated using absorption and emission studies. Thermal melting and viscosity experiments were further performed to determine the mode of binding of 1 with CT-DNA. Spectroscopic and viscosity investigations revealed an intercalative binding mode of 1 with CT-DNA. The ligand and its zinc complex were screened for their biological activity against bacterial species and fungi. Activity data show that the metal complex has more antibacterial and antifungal activity than the parent Schiff base ligand and against those bacterial or fungi species. © Indian Academy of Sciences.


Dey D.,Raghunathpur College | Kaur G.,Indian Institute of Science | Patra M.,Raghunathpur College | Choudhury A.R.,Indian Institute of Science | And 2 more authors.
Inorganica Chimica Acta | Year: 2014

A perfectly linear trinuclear zinc(II) complex [Zn3L 2(μ-O2CCH3)2] (1) containing a (N,O)-donor Schiff base ligand, (H2L = N,N′- bis(salicyaldehydene)-1,3-diaminopropan-2-ol) has been synthesized and characterized by single crystal X-ray diffraction study. The X-ray crystal structure of 1 contains three zinc(II) centers which are inter-connected through μ2-phenolato and μ-acetato bridges. The terminal zinc centers are in square pyramid geometry and central zinc ion is in distorted octahedral coordination geometry. Both H2L and 1 exhibit good fluorescence properties in solution. 1 has been used as a precursor to fabricate zinc oxide nanoparticles (ZnONPs) by pyrolytic method. ZnONP has been characterized by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), FT-IR spectroscopy and UV-Vis spectroscopy techniques. ZnONP has been employed as photocatalytic agent to degrade the organic dye, viz. Methylene blue under visible light and by exposing to visible light for 1 h, ZnONP degraded methylene blue dye nearly 80%. © 2014 Elsevier B.V. All rights reserved.

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