Showing papers by "S. B. Majumder published in 2022"

Multifunctional behaviour in B-site disordered double perovskite EuPrCoMnO6

Abstract: We report magnetic, transport, dielectric, and complex impedance of polycrystalline double perovskite EuPrCoMnO6 which crystallizes in disordered orthorhombic phase with space group Pnma. The DC magnetization shows two successive ferromagnetic transitions around 146 K and 138 K. The temperature and magnetic field variation of DC-susceptibility suggest the existence of Griffith phase and spontaneous exchange bias. AC susceptibility measurement shows a glassy dynamic behaviour near ferromagnetic transition. Further, a re-entrant glassy dynamic state is seen at a low temperature around 40 K. Temperature-dependent resistivity shows semiconducting/insulating nature, which gets increased under the application of magnetic field, showing positive magnetoresistance. The dielectric study shows usual frequency-dependent step-like behaviour with a colossal dielectric constant near room temperature. The complex impedance study shows both grain and grain boundary contribute to the electrical properties. The observed properties suggest the material can be used for spintronic devices and high dielectric applications.

Manipulating electron-spin polarization using cysteine-DNA chiral conjugates.

Abstract: The chiral molecules are potential generators of high spin-filters due to their inherent inversion asymmetric helical electric field. We report a controlled spin-selective transmission of electrons through self-assembled monolayers of 15 base-paired double-stranded deoxyribonucleic acid functionalized with two enantiomeric cysteine molecules on gold explored through the quantum mechanical tunneling effect. We observed a controlled spin polarization of 33% with dextro-cysteine, whereas a mere 8% was observed with levo-cysteine molecules using these functionalizations at room temperature. The manipulation of electron's spin merely through such a small molecule could lead to significant advancement in the spin-dependent charge transport phenomena and related applications.

Fabrication of a Label‐free Femtomolar Electrochemical Mercury Ion Biosensor based on Oligonucleotide Receptor Layers Hybridized with Multi‐Walled Carbon Nanotubes

Abstract: The feasibility of designing a highly selective and sensitive label-free cost-effective biosensor to determine Hg2+ ions using gold electrodes functionalized with short-chain, thymine-rich, ss-DNA oligonucleotides wrapped MWNTs is examined. The potassium ferricyanide was used as a redox marker for analytical signal generation. Biosensor response was based on the difference in the electrochemical signal before and after subjecting it to a sample containing Hg2+ ions. The lowest detection limit of 1 femtomolar (fM) of mercury ions was observed in the aqueous medium, together with good selectivity against common metal cations. The method developed was successfully applied for the determination of Hg2+ ions in environmental waste water samples.

Generalized solubility limit approach on vanadium based cathode materials for lithium-ion batteries

Abstract: In this article, we address the issue of vanadium dissolution pertinent in several vanadium containing cathode materials using the solubility limit approach. This article is divided into three major sections....

Microscopic insights of magnetism in Sm$ _{2} $NiMnO$ _{6} $ double perovskite

Abstract: Supriyo Majumder, Malvika Tripathi, H. E. Fischer, D. O. de Souza, L. Olivi, A. K. Sinha , R. J. Choudharya,∗ and D. M. Phase UGC DAE Consortium for Scientific Research, Indore 452001, India Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark Institut Laue-Langevin, 38042 Grenoble Cedex, France Elettra Sicrotrone Trieste S.C.p.A., SS 14-km 163.5, 34149 Basovizza, Italy HXAL, SUS, Raja Ramanna Centre for Advanced Technology, Indore 452013, India Department of Physics, School of Engineering UPES, Dehradun 248007, India

Synthesis and electrochemical performance of in‐situ and ex‐situ carbon‐ coated Na 2 Ti 3 O 7 , as a promising anode for sodium‐ion batteries

Abstract: Insertion-type layered Na2Ti3O7 has attracted the attention of the researchers and is considered to be one of the promising low-voltage anode materiasl for sodium-ion batteries. In spite of its fascinating electrochemical properties, the low electronic conductivity and structural instability of Na2Ti3O7 are major drawbacks that restrict its practical application. Surface modification with pyrolytic carbon is one of the effective ways to reduce irreversible capacity loss caused by electrolytic degradation. In this work, attempts have been made to investigate the effects of different carbon coating approaches on the electrochemical properties of sol-gel-synthesized Na2Ti3O7 microrods. The as-synthesized Na2Ti3O7 rods are coated with a uniform carbon layer both by in-situ and ex-situ methods using citric acid and polyvinyl alcohol as carbon source, respectively. Ex-situ carbon-coated Na2Ti3O7 (Na2Ti3O7@C), due to better coating uniformity and higher graphitized carbon percentage, shows enhanced cyclability and rate performance compared to bare material and in-situ carbon composite (Na2Ti3O7/C). Following the ex-situ carbonization method using PVA as carbon source, it is found that increase of carbon content from 5wt% to 10wt% significantly improves its electrochemical properties. However, further increase in PVA amount has adverse effect on the cycling as well as rate performance of Na2Ti3[email protected] Surface modified Na2Ti3O7@C with optimum carbon content (10wt% C) shows improved cycling capacity (capacity retention ∼74.75% after100 cycle) and rate performance (∼67 mAhg-1 at 1.5 Ag-1). Both excess and inadequate carbon content have detrimental effect on the electrochemical properties of Na2Ti3O7 anode.

Realizing Low-Temperature Charge-Transfer-Type Insulating Ground State in Strained V2O3 Thin Film

Abstract: Controlling the electronic properties of strongly correlated systems, observing electron–electron correlation-driven metal to insulator transition (MIT) is a key point for the next-generation solid-state Mottronic devices. Thus, the knowledge of the exact nature of the insulating state is an essential need to enhance the functionality of the material. Therefore, we have investigated the electronic nature of the insulating state of a classical Mott insulator V2O3 thin film (epitaxial) using low-temperature (LT) (120 K) resonant photoemission spectroscopy and X-ray absorption near-edge spectroscopy measurements. Temperature-dependent valence band spectra (VBS) reflect the transfer of spectral weight from the metallic coherent band (AM) near the Fermi level (EF) to the insulating Mott–Hubbard screened band (CI) at a binding energy of around 2.4 eV. Such a transfer of spectral weight upon MIT leads to vanishing of the density of states at EF and opens a band gap. The strong presence of the 3dnL final state is observed near the EF of LT VBS, confirming the presence of an O 2p band participating in low-energy charge fluctuation. This study further endorses the charge-transfer (CT)-type (U > Δ) insulating nature of a strained V2O3 thin film at LT, unlike its bulk counterpart, which is placed intermediate (U–Δ) between the CT and the Mott–Hubbard regime. Modifying the electronic ground state of V2O3 to the CT nature via the epitaxial strain in thin films provides a way to tailor the electronic energetics, with its implications to next-generation correlation-derived switching devices.

Hierarchical Carbon Composites for High-Energy/Power-Density and High-Reliability Supercapacitors with Low Aging Rate.

Abstract: A facile method for preparing hierarchical carbon composites that contain activated carbon (AC), carbon nanospheres (CNSs), and carbon nanotubes (CNTs) for use as the electrode material in supercapacitors (SCs) is developed. The CNS/CNT network enables the formation of three-dimensional conducting pathways within the highly porous AC matrix, effectively reducing the internal resistance of an SC electrode. The specific capacitance, cyclability, voltage window, temperature profile during charging/discharging, leakage current, gas evolution, and self-discharge of the fabricated SCs are systematically investigated and the optimal CNS/CNT ratio is determined. A 2.5 V floating aging test at 70 °C is performed on SCs made with various hierarchical carbon electrodes. Electrochemical impedance spectroscopy, postmortem electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analyses are conducted to examine the electrode aging behavior. A hierarchical carbon architecture with an appropriate AC/CNS/CNT constituent ratio can significantly improve charge-discharge performance, increase cell reliability, and decrease the aging-related degradation rate.

The synthesis of novel porous graphene anodes for fast charging and improved electrochemical performance for lithium-ion batteries

Abstract: ABSTRACT As part of sustainable development goals seven and thirteen, electric vehicles (EV) are taking over internal combustion engine vehicles by using battery packs as their power source. One major concern for the EV sector is the charging time of lithium-ion (Li-ion) batteries. Advancing the battery pack industry and the EV sector will benefit economically and environmentally by creating pores on the graphene anode using the NaCl activation method, eventually leading to high performance and efficiency in Li-ion batteries. Accordingly, the present study focused on fabricating novel macroporous graphene (MPG) anodes for fast-charging Li-ion batteries. Macropores increase the anode surface area, thereby enhancing lithiation. The performance of the novel MPG anode is compared with that of the commercial mesocarbon microbead (MCMB) anode. As a result, the MPG anode exhibits a 15% faster charge than the MCMB at a 0.1 C rate. Moreover, the specific capacity of the MPG anode retains 16.3% higher than the MCMB anode after the completion of the 100th cycle.

Electrochemical Performance of Electrophoretically Deposited Nickel/ Cobalt Antimony Oxide-Carbon Black Negative Electrodes for Alkali-Ion Batteries

Abstract: In recent years, the requirement for portable power has increased due to the miniaturization of electronic devices. Developing rechargeable lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), with high power and energy density, long cycle life is the need of the hour. In this present work, nickel antimony oxide (NiSb2O6; NSO) and cobalt antimony oxide (CoSb2O6; CSO), two relatively new conversion-type anode materials have been explored as negative electrodes for both LIB and SIB. Conversion-type anode materials offer many advantages like ease of synthesis, requires inexpensive and abundantly available precursors and exhibit high specific capacities. Besides, relatively higher redox potentials of such anodes minimize the chance of lithium dendrites formation. A simple co-precipitation followed by calcination at 1000◦C leads to formation of tri-rutile phase NSO and CSO powder. The microstructural analysis using scanning electron microscopy of NSO and CSO powder confirms the formation of asymmetric particles having size in the range of 50-100nm. FTIR and Raman results of the calcined NSO and CSO powder indicate the presence of Sb2O6 2- units along with Ni+2/Co+2. The NSO-CB and CSO-CB electrodes are fabricated by facile and reproducible electrophoretic deposition (EPD) technique. EPD is a facile colloidal technique which can be adopted to fabricate different types of materials like conversion, insertion and alloying anode on any complex shaped substrate. Besides being an economical and ecofriendly process, EPD offers excellent reproducibility and control over the deposited film thickness. At a deposition parameter of 100V for 3minutes, well-adhered and uniform coating of NSO-CB and CSO-CB are obtained on the copper current collector. The SEM micrographs of the EPD grown electrodes substantiate the formation of a porous film with uniform distribution of active materials and carbon black (CB). Detailed ex-situ XRD analysis has been carried out to find out the lithium storage mechanism of NiSb2O6 material. It is observed that the NiSb2O6 breaks into NiO and Sb2O5 in the first lithiation step. These oxides further participate in reversible lithiation and de-lithiation reactions in the subsequent cycles. When used as a lithium-ion anode, the NSO-CB and CSO-CB electrode deliver a stable reversible capacity of 594mAhg-1 and 612mAhg-1, respectively, at a specific current of 0.5Ag-1 after 100 cycles (Fig 1(a)). Both the anode material exhibits excellent rate performance delivering a specific capacity of 397mAhg-1 and 510mAhg-1, respectively, at a high specific current of 4Ag-1. On the other hand, as a sodium-ion anode, the NSO-CB and CSO-CB electrodes are able deliver a stable reversible capacity of 255mAhg-1 and 150mAhg-1, respectively, at a specific current of 0.1Ag-1 after 50 cycles (shown in Fig 1(b)). Cyclic voltametric study at different scan rates reveals that the electrochemical reactions of NSO and CSO are mainly dominated by diffusion-controlled behavior. Therefore, both NSO and CSO can be a potential anode material for alkali-ion batteries. Fig 1: Cyclability performance of NSO-CB and CSO-CB electrodes as (a) lithium-ion battery anode, cycled at 0.5mAg-1 specific current and (b) sodium-ion battery anode, cycled at 0.1mAg-1 specific current in the voltage range of 0.01-2.5V. Figure 1

Robust electronic and tunable magnetic states in Sm2 NiMnO6 ferromagnetic insulator

Abstract: Ferromagnetic insulators (FM-Is) are the materials of interest for the new generation quantum electronic applications. Here, we have investigated the physical observables depicting FM-I ground states in epitaxial Sm2NiMnO6 (SNMO) double perovskite thin films fabricated under different conditions to realize the different level of Ni/Mn anti-site disorders (ASDs). The presence of ASDs immensely influence the characteristic magnetic and anisotropy behaviors in SNMO system by introducing short scale antiferromagnetic interactions in predominant long range FM ordered host matrix. Charge disproportion between cation sites, in the form of Ni2+ + Mn4+ → Ni3+ + Mn3+, causes mixed valency in both Ni and Mn species, which is found insensitive to ASD concentrations. Temperature dependent photo emission, photo absorption measurements duly combined with cluster model configuration interaction simulations, suggest that the eigenstates of Ni and Mn cations can be satisfactorily described as a linear combination of the unscreened d n and screened dn+1L̲ ( L̲ : O 2p hole) states. The electronic structure across the Fermi level (E F) exhibits closely spaced Ni 3d, Mn 3d and O 2p states. From occupied and unoccupied bands, estimated values of the Coulomb repulsion energy (U) and ligand to metal charge transfer energy (Δ), indicate charge transfer insulating nature, where remarkable modification in Ni/Mn 3d—O 2p hybridization takes place across the FM transition temperature. Existence of ASD broadens the Ni, Mn 3d spectral features, whereas the spectral positions are found to be unaltered. Hereby, present work demonstrates SNMO thin film as a FM-I system, where the FM state can be tuned by manipulating ASD in the crystal structure, while the I state remains intact.

Existence of inter coupled structural, electronic and magnetic states in Sm$ _{2} $NiMnO$ _{6} $ double perovskite

Abstract: . Coupling between different interactions allows to control physical aspects in multifunctional materials by perturbing any of the degrees of freedom. Here, we aim to probe the correlation among structural, electronic and magnetic observables of Sm 2 NiMnO 6 ferromagnetic insulator double perovskite. Our employed methodology includes thermal evolution of synchrotron X-ray diffraction, near edge and extended edge hard X-ray absorption spectroscopy and bulk magnetometry. The magnetic ordering in SNMO adopts two transitions, at T C =159.6K due to ferromagnetic arrangement of Ni-Mn sublattice and at T d =34.1K because of anti-parallel alignment of polarized Sm paramagnetic moments with respect to Ni-Mn network. The global as well as local crystal structure of SNMO undergoes isostructural transitions across T C and T d , observed by means of temperature dependent variation in Ni/Mn-O, Ni-Mn bonding characters and super exchange angle in Ni-O-Mn linkage. Hybridization between Ni, Mn 3 d , O 2 p electronic states is also modified in the vicinity of magnetic transition. On the other hand, the signature of Ni/Mn anti-site disorders are evidenced from local structure and magnetization analysis. The change in crystal environments governs the magnetic response by imposing alteration in metal - ligand orbital overlap. Utilizing these complimentary probes we have found that structural, electronic and magnetic states are inter-coupled in SNMO which makes it a potential platform for technological usage.

Isolation and Identification of Arsenic Hyper-Tolerant Bacterium with Potential Plant Growth Promoting Properties from Soil

Abstract: The soil and groundwater of the Bhagobangola I block of Murshidabad district, West Bengal, India is severely arsenic-contaminated. A bacterium was isolated from the garden soil of the Mahishasthali village, which could tolerate 36.49 mM arsenic (III), 280.44 mM arsenic (V) and 63 mM chromium (III), which makes it arsenic (III and V) and chromium (III) hyper-tolerant bacterium. The growth pattern of this bacterium does not show much alteration in the presence of 10 mM arsenic (III) and chromium (III), emphasizing its resistance to these heavy metals. Scanning electron microscopic analysis depicted this bacterium to be rod-shaped with a size of ~1.45 µm. 16S rDNA sequencing, followed by subsequent phylogenetic analysis, established the identity of this bacterium as Microbacterium paraoxydans. This bacterium is capable of bioremediation of arsenic and showed 30.8% and 35.2% of bioremediation for 1mM and 22.6%, and 30.5% of bioremediation for 4mM arsenite, over a period of 24 and 48 h, respectively. Microbacterium paraoxydans also exhibits potential plant growth-promoting properties such as nitrogen fixation, phosphate solubilization, indole-3-acetic acid production and production of siderophores. Therefore, the heavy metal resistance, bioremediation potential and plant growth-promoting potential of the bacterium could be utilized not only for reduction in arsenic toxicity in soil and groundwater but also for plant growth promotion.

Magnetic properties of disordered polycrystalline bulk Sm$ _{2} $NiMnO$ _{6} $ double perovskite

Abstract: . The structural, electronic and magnetic properties of anti-site disordered Sm 2 NiMnO 6 double perovskite has been studied. ordered double perovskite is commonly believed to show two distinct magnetic phase transitions viz, paramagnetic to ferromagnetic (FM) transition at T = T C due to Ni-O-Mn super exchange interaction and another transition at T = T d due to coupling of RE spins with Ni-Mn network. In our present study, we have observed that the presence of intrinsic B-site disorder results in an additional antiferromagnetic (AFM) coupling, mediated via Ni-O-Ni and Mn-O-Mn local bond pairs. As a consequence, the magnetic behavior of SNMO comprises of co-existing FM-AFM phases, which are respectively governed by the anti-site ordered and disordered structures. Field dependent inverted cusp like trend in M(T) and two step reversible loop behavior in M(H) measurements indicate the presence of competing FM-AFM phases over a wide range of temperature values (T d < T < T C ).

FEM modelling of magnetoelectric coupling in (2-2)LSMO/ P(VDF-TrFE) polymer composite

Abstract: Strain mediated magnetoelectric (ME) coupling effect has been investigated in bilayer structure of LSMO/P (VDF-TrFE) nanocomposite in the transverse ME mode. In the transverse mode, Finite Element Method (FEM) based small signal analysis has been performed by the COMSOL Multiphysics 6.0 software. La0.7Sr0.3MnO3(LSMO)/P (VDF-TrFE) nanocomposite (2-2) has been prepared by gluing LSMO pellet with P(VDF-TrFE) polymer film. This bilayer structure shows multiferroic property at room temperature. Simulated FEM modelverifies the magneto-strictive property of LSMO layer and explained the experimental results.Experimental and simulated ME coupling coefficient are found to be very close to each other.

Solar energy harvesting in magnetoelectric coupled manganese ferrite nanoparticles incorporated nanocomposite polymer films

Abstract: Poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) based pyroelectric as well as magnetoelectric materials offer great promises for energy harvesting for flexible and wearable applications. Hence, this work focus on solar energy harvesting as well as magnetoelectric phenomenon in two phase nanocomposite film where the constituting phases are manganese ferrite (MnFe 2 O 4 ) nanoparticles and P(VDF-TrFE) polymer. Composite films have been prepared using solution casting technique. X-ray diffraction result shows higher crystallinity of these films. The ferroelectric, magnetic and magnetoelectric properties in variation with applied field and volume percentage of ferrite nanoparticles have been investigated. The preparation condition was optimized in such a way that it results improved ferroelectric polarization of nanocomposite film after incorporation of small amount of ferrite nanoparticles. The maximum magnetoelectric-coupling coefficient of about 156 mV/Oe-Cm was obtained for optimum nanocomposite film when DC bias field was applied perpendicular to electric polarization direction. From a pyroelectric device perspective, solar energy harvesting is also reported. An open circuit voltage of 5V and short circuit current of order of ~1 nA is demonstrated without any pre amplification. Hence, the combination of magnetoelectric and pyroelectric properties of nanocomposite film presented here indicate as a perfect candidate for smart materials, spintronics devices and specified magnetoelectric-based applications.

Anti-site disorder driven unusual magnetic properties in Sm2NiMnO6 double perovskite

Abstract: The structural, electronic and magnetic properties of anti-site disordered Sm2NiMnO6 double perovskite has been studied. RE2NiMnO6 (RE: rare-earth) ordered double perovskite is commonly believed to show two distinct magnetic phase transitions viz, paramagnetic to ferromagnetic (FM) transition at T = TC due to Ni-OMn super exchange interaction and another transition at T = Td due to coupling of RE spins with Ni-Mn network. In our present study, we have observed that the presence of intrinsic B-site disorder results in an additional antiferromagnetic (AFM) coupling, mediated via Ni-O-Ni and Mn-O-Mn local bond pairs. As a consequence, the magnetic behavior of SNMO comprises of co-existing FM-AFM phases, which are respectively governed by the anti-site ordered and disordered structures. Field dependent inverted cusp like trend in M(T) and two step reversible loop behavior in M(H) measurements indicate the presence of competing FM-AFM phases over a wide range of temperature values (Td < T < TC).

Exchange bias in Sm$ _{2} $NiMnO$ _{6}$/BaTiO$ _{3}$ ferromagnetic-diamagnetic heterostructure thin films

Abstract: Exchange bias (EB) shifts are commonly reported for the ferromagnetic (FM)/antiferromagnetic (AFM) bilayer systems. While stoichiometric ordered Sm 2 NiMnO 6 (SNMO) and BaTiO 3 (BTO) are known to possesses FM and diamagnetic orderings respectively, here we have demonstrated the cooling field dependent EB and training effects in epitaxial SNMO/BTO/SNMO (SBS) heterostructure thin films. The polarized Raman spectroscopy and magnetometric studies reveal the presence of anti-site cation disorders in background of ordered lattice in SNMO layers, which introduces Ni-O-Ni or Mn-O-Mn local AFM interactions in long range Ni-O-Mn FM ordered host matrix. We have also presented growth direction manipulation of the degree of cation disorders in the SNMO system. Polarization dependent X-ray absorption measurements, duly combined with configuration interaction simulations suggest charge transfer from Ni/Mn 3 d to Ti 3 d orbitals through O 2 p orbitals across the SNMO/BTO (SB) interfaces, which can induce magnetism in the BTO spacer layer. The observed exchange bias in SBS heterostructures is discussed considering the pinning of moments due to exchange coupling at SB (or BTO/SNMO) sandwich interface.