Brajesh Pandey

• Ph. D.
• Professor (Associate) at Symbiosis Institute of Technology

A charged compact star is modelled within the framework of general relativity and electromagnetism to investigate the intricate complexities arising from charge accumulation through the accretion of surrounding charged baryonic matter, charged dark matter, or both. The Einstein–Maxwell field equations are solved for the compact star PSRJ0740+6620 i...

This study is about the influence of film thickness and temperature on the magnetic characteristics of Co/Au bilayers. Through a combination of X-ray Reflectivity (XRR), Reflectivity High Energy Electron Diffraction (RHEED), and Magneto Optic Kerr Effect (MOKE) in situ measurements, we meticulously examine how these parameters impact the behavior o...

In this experimental study, zinc oxide nanoparticles (ZnO-NPs) are synthesized using Moringa oleifera extract and calcined at 400 °C. These biologically synthesized ZnO-NPs were mixed in 1:1 proportion with organic (oil) and quasi-organic (varnish) binder separately. These mixtures were individually coated on three substrates: paper, wood, and fabr...

We present a singularity free and smoothly connected complete solution for a three-layered compact star with deconfined quark matter core surrounded by coherent quantum fluid of a Bose-Einstein condensate, all enclosed under a thin envelope of a repulsive neutron-Coulomb fluid. A modified form of Buchdahl-I type spatial metric is used as a seed to...

Silver nanoparticles (Ag-NPs) demonstrate unique properties and their use is exponentially increasing in various applications. The potential impact of Ag-NPs on human health is debatable in terms of toxicity. The present study deals with MTT(3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium-bromide) assay on Ag-NPs. We measured the cell activ...

We present a singularity free and smoothly connected complete solution for a three-layered compact star with deconfined quark matter core surrounded by coherent quantum fluid of a Bose-Einstein condensate, all enclosed under a thin envelope of a repulsive neutron-Coulomb fluid. A modified form of Buchdahl-I type spatial metric is used as a seed to...

This paper provides a simplified description for simulating the coupling of dark energy with baryonic matter by considering a super-dense pulsar PSRJ1614-2230 as the model star. The starting equation of state for modeling the dark energy is motivated by the MIT Bag model for spherically confined hadrons and the observational evidences of its repuls...

The relativistic evolution of a compact star, PSRJ0740+6620is explored using Einstein field equations to study the non-linear response of confined gravitating matter in the background scalar field of dark energy. The embedding class one approach is used to simulate the interior metric potentials in the anisotropic regime. The generalised solution c...

Ultra-thin ferromagnetic films coupled with nonmagnetic layers are extensively studied for their potential applications in data storage. The conventional memory industry is currently in the spotlight, with researchers worldwide contributing toward better data storage technologies that can tackle the data storage problems posed by this era of big da...

The key idea in this paper is to use Einstein field equations to model and simulate a hybrid star consisting of gravitating baryonic matter and a linearly coupled repulsive dark energy field. The interior metric potential of class, Tolman-Buchdahl type, is used in the anisotropic regime. The matching boundary conditions are used to fix the family o...

Silver nanoparticles (AgNPs) display unique plasmonic and antimicrobial properties, enabling them to be helpful in various industrial and consumer products. However, previous studies showed that the commercially acquired silver nanoparticles exhibit toxicity even in small doses. Hence, it was imperative to determine suitable synthesis techniques th...

Iron oxyhydroxide (γ-FeOOH) films were prepared by nitrate reduction mechanism under cathodic potential. Phase transformation to iron oxide (α-Fe2O3) was carried out by post-deposition annealing treatment at two different temperatures, 300 and 500 °C, in Ar and air environments. The variation in super capacitive behaviour/contribution in iron oxyhy...

Background Copper oxide nanoparticles have become very important due to their numerous applications and ease of synthesis. Out of the two oxides of copper, cuprous oxide exhibits better antibacterial, antimicrobial, and antifouling properties. Objective The study aimed to find a way of synthesizing stable and eco-friendly oxide of copper and test...

This poster is based on our work " Temperature-induced interface roughness and spin reorientation transition in Co/Au multilayers thin films". In this work, we are trying to show the importance of surface/interface roughness with respect to temperature. The studies are done using In-situ characterization techniques yielding very good results.

Spin reorientation transition (SRT) due to high temperature has been studied in Co/Au multilayered thin films. The effect of temperature on structural and magnetic properties of the thin films has been investigated. Film thickness and interface roughness has been studied by measuring x-ray reflectivity. Multilayers are thermodynamically stable, and...

Nickel oxide (NiO) nanoparticles was prepared using top-down method in the size range 12-70 nm via ball milling of their bulk. Bulk size NiO was prepared by heating of Ni(NO3)2.6H2O in air. This NiO powder was then milled in planetary ball mill keeping a fixed powder to ball ratio. Strain was introduced in the powder during milling process. The str...

Metal matrix composites have good mechanical properties as comparison to metals during various operations. Hence, different engineering applications started using MMC a very good choice in substituting metals. The paper provides a review on turning of strengthened aluminium metal matrix composites (AMMC) particularly reinforced particles. Also pape...

Iron/iron-oxide nano particles are synthesized using electrodeposition technique. The particles are well crystalline bcc iron with disordered oxides of iron on the surface. The particles show very small coercivity displaying superparamagnetic behavior of the iron core in magnetization measurement using Vibrating Sample Magnetometer. But the same pa...

The shape-dependent surface properties of iron oxides are being paid increasing attention for their many advanced and synergistic applications. The present investigation deals with the preparation of pure and lithiated 3D iron oxide through a simple and single-step synthesis route. The nano-hierarchical flowers were synthesized by adopting a semi-a...

Two families of Co/Au multilayer films with different interlayer magnetostatic coupling were grown by the DC magnetron sputtering technique. The structure of these films was analyzed by X-ray diffraction (XRD), and the magnetic properties by vibrating sample magnetometer (VSM) and ferromagnetic resonance (FMR) spectroscopy. All these techniques giv...

Magnetic particles as matrix for enzyme immobilization have been used and due to the enzymatic derivative can be easily removed from the reaction mixture by a magnetic field. This work presents a study about the synthesis and characterization of iron phases into magnetic montmorillonite clay (mMMT) and magnetic diatomaceous earth (mDE) by 57Fe Möss...

Iron/iron-oxide nano particles are synthesized using electrodeposition technique. The particles are well crystalline bcc iron with disordered oxides of iron on the surface. The particles show very small coercivity displaying superparamagnetic behavior of the iron core in magnetization measurement using Vibrating Sample Magnetometer. But the same pa...

Nanosize chromium ferrite (CrF) powder samples were synthesized by citrate precursor route in the size range of 6 to 35 nm. The structural and magnetic behaviour of these samples were studied using X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and Mössbauer spectroscopic techniques. Synthesized chromium ferrite powders were in good p...

Out of the five major mass extinction, which have taken place in the history of life, Cretaceous–Tertiary boundary (KTB) mass extinction was the 2nd most disastrous, the most severe being that at Permian–Triassic boundary (PTB). On the basis of iridium anomaly at a number of KTB sites it has been established that the cause of extinction was impact...

In our previous study we attempted to see the effect of cerium doping (Ce/Fe ratio 0.015 to 0.074) on goethite matrix and conversion of doped goethite to hematite. In the present communication, nano-structured {alpha}-Fe{sub 2}O{sub 3}-CeO{sub 2} composite with Fe/Ce weight ratio as 1.1 has been synthesized by calcination of goethite-cerium hydroxi...

PrRh2Si2 is highly anisotropic Ising-type antiferromagnetic system. The ordering temperature (T N~ 68K) of PrRh2Si2 is exceptionally high on the de-Gennes scale in the family of RRh2Si2 (R = rare earths). The reason for this anomalous behaviour is not clear. It is believed that the presence of uniaxial anisotropy assists in enhancing the T N. The M...

Mixing characteristics of Si and Al or Cr in Fe has been studied in ball milled Fe75Si15M10 (with M = Al, Cr) alloys in detail. Mössbauer spectroscopic study shows that even up to 80h of milling a large number of iron atoms remain uninteracted and give 33.0T sextet. The portion which mixes up gives a magnetic component with 31.5T of B hf and parama...

Chemical co-precipitation method was used to synthesize nano-structured α-Fe2O3-CeO2 composite by calcination of the goethite–cerium hydroxide precursor. It was observed that the precursor contained goethite matrix doped with cerium. Calcination of the precursor at 400°C showed the formation of nanosize hematite. Mössbauer spectra show the presence...

Bi1−xSmxFeO3 (x = 0.0–0.2) ceramic samples were prepared by mechanical activation assisted solid-state-reaction synthesis. A stoichiometric mixture of Bi2O3, Sm2O3, and Fe2O3 powders was mechanically milled and this was followed by heat treatment at 700 °C for 1 h. Room temperature x-ray diffraction patterns confirmed the formation of perovskite st...

An attempt to synthesize multiferroic BiFeO3 by mechanical milling Bi2O3 and Fe2O3 powders showed very interesting results. 100 h milled powder was calcined at different temperatures and it was found that the BiFeO3 phase forms at 700°C followed by slow cooling. The magnetic behaviour and phase formation crucially depended on the cooling conditions...

We report the structural and magnetic properties of the nanocrystalline Fe75Si15M10 (M-Al and Cr) powders prepared by mechanical alloying. The milling process produced a non-equilibrium solid solutions of bcc alpha-Fe(Si,Cr) and alpha-Fe(Si,Al). The average dislocation density increases and the average crystallite size decreases with increasing mil...

PrRh2Si2 is highly anisotropic Ising-type antiferromagnetic system. The ordering temperature (T N~ 68 K) of PrRh2Si2 is exceptionally high on the de-Gennes scale in the family of RRh2Si2 (R = rare earths). The reason for this anomalous behaviour is not clear. It is believed that the presence of uniaxial anisotropy assists in enhancing the T N. The...

Europium-doped cubic barium titanate (BT) nanocrystals with % [Eu/Ti] mol ratio varying from 0.05 to 0.25 were prepared through hydrothermal route. The nano nature of these powders was confirmed by XRD and TEM studies. Pellets were prepared after calcining the powders at 1000 °C for 2 h. These pellets were annealed at 200, 500, 700 and 1000 °C for...

Two groups of ferrite namely zinc ferrite and chromium ferrite were synthesized by citrate precursor route in the size range of 8 to 35nm. We have studied the structural and magnetic behaviour of these ferrites using X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and Mössbauer spectroscopic techniques. Our studies show that the nanocr...

Lattice deformations and texture were induced in Fe 72 Al 28 and Fe 75 Ni 25 alloys by filing and cold rolling. The deformations and deformation-induced atomic and magnetic domain rearrangements were studied using X-ray diffraction, magnetization measurement and positron annihila-tion coincidence Doppler broadening spectroscopy. It is observed that...

Mechanical strain was induced in Fe-25 at.% Ni alloy by filing the ingots into powder form. The phase transformations induced by the deformation thus caused and subsequent annealing were studied by x-ray diffraction, magnetization measurement and Mössbauer spectroscopy. It is concluded that around one-third of the Fe atoms became segregated from th...

Manganese doped cubic barium titanate nanocrystals with [Mn/Ti] mole percent varying from 0.1 to 3 were prepared through hydrothermal route at 150 °C. The mean crystallite diameters obtained for different Mn concentrations varied within 26 to 30 nm. TEM of a typical sample showed most of the particles as single crystallites (particle size 15–40 nm)...

Here we report on the synthesis of multiferroic BiFeO3 ceramics by mechanical activation and detailed investigation into its magnetic behavior. The mechanically milled BiFeO3 ceramic was calcined at temperatures up to 800°C X-ray diffraction studies showed that the maximum amount of BiFeO3 phase forms upon calcination at 700°C Vibrating sample magn...

Nano-sized barium titanate (BT) and Ce-doped barium titanate samples were synthesized by simple hydrothermal technique at 150°C from Ba(OH)2·8H2O, TiO2 and Ce(NO3)3·6H2O. The mean crystallite diameters (MCD) along (101) plane obtained from XRD data were in the range of 24–28nm for pure and Ce-doped samples. The TEM micrographs confirmed the nano-si...

Interesting differences were noticed in the alloying process during ball milling of Fe-10wt.% Cr and Fe-20wt.% Cr alloys by 57Fe Mössbauer spectroscopic studies. In both cases, there is almost no diffusion of Fe in Cr or vice versa up to 20h of milling time. As the powders are milled for another 20h substantive changes occur in the Mössbauer spectr...

The structural and compositional changes during mechanical milling of Fe–Cr powder (10 wt% Cr) were followed by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD), Mössbauer spectroscopy and magnetization measurement. All these techniques give complementary information about the alloying process during millin...

Mössbauer spectroscopic studies of two sedimentary layers from Petriccio section in Gubbio formation are presented. It is found that these layers have almost the same iron phases nanophase hematite and phyllosilicate and with the same compositions as those in the Cretaceous-Tertiary Boundary (KTB) in Petriccio. The two layers also show enhancement...

Vibrating sample magnetometer (VSM) and Mössbauer spectroscopy are used to characterize the magnetic behaviour of fine magnetite particles obtained from (i) pure goethite and (ii) Ni-doped goethite, in ammoniacal solution. The latter sample has 0.4 wt% Ni which has significantly changed the properties of the sample. The Ni-doped magnetite shows a m...

Fe72−x Al28Crx (x = 0,2,4,6) are made by arc melting a mixture of constituent elements in stoichiometric proportion, in argon atmosphere. The ingots so obtained are filed to make powder samples thereby giving them substantial mechanical deformation. It is observed that as-powdered samples show hyperfine field distribution typical of α-phase, where...

Fe72-xAl28Crx alloys (x = 0, 2, 4, 6) are made by arc melting a mixture of constituent elements in stoichiometric proportion, in argon atmosphere. The ingots so obtained are filed to make powder samples thereby giving them substantial mechanical deformation. It is observed that as-powdered samples show hyperfine field distribution typical of α-phas...

Positron lifetime measurements in deformed Fe-Al-Ti alloys, obtained by filing the homogenized ingots show that monovacancies are created during the filing process. This is in contrast with known results on deformation due to rolling where dislocations have been reported as the major defect type. These results together with those from Mössbauer spe...

Mechanical deformation is induced in Fe72−xAl28Tix alloys (x=0,2,6,9) by filing cast and homogenized ingots to fine powder. The phase transformations induced due to the deformation and subsequent annealing are followed by Mössbauer spectroscopy, XRD, and magnetization measurement. As a result of filing, the long range order is destroyed and pockets...