Papers by Satya Pal Singh
Journal of Advanced Scientific Research
The work aims to elucidate the optical and structural properties of silicon hydride nanoclusters ... more The work aims to elucidate the optical and structural properties of silicon hydride nanoclusters and its bulk via density functional calculations. The molecular geometry is fully optimized with the help of DFT method using Gaussian 09 and Gaussian View 05 Software. Bandgaps are calculated using two approaches; first one using HOMO-LUMO concept and the second one is extracted from UV-vis spectrum. The calculated bandgap of silicon hydride is 3.7 eV. XRD data has also been analyzed using VESTA software, which shows the presence of a silicon matrix that contains organized silicon clusters forming an amorphous silicon matrix. A comprehensive investigation of amorphous films by X-ray diffraction (XRD) shows that the strongest peak in XRD patterns occurs at approximately 30.95°. Using XRD data, average size of optimized silicon hydride nano-cluster has been found to be 158.5 nm. Apparently large value of the cluster size can be attributed to the partially amorphous nature of silicon hydri...
Journal of Advanced Scientific Research
Mg-doped ZnO alloy thin films having hexagonal Wurtzite structures were prepared using the Sol-Ge... more Mg-doped ZnO alloy thin films having hexagonal Wurtzite structures were prepared using the Sol-Gel method. The doping results into, increased surface roughness and reduced grain size. Photonic applications are made easier by altering the optical bandgap of ZnO nano-structured thin films doped with various components. Mg metal atom doped ZnO films are an excellent example for study. In this work, the thin film of Mg-doped ZnO is formed on glass substrate via dip coating method with varied concentration of dopant. Dip-coating method is one of the cheapest methods. SEM, Raman spectroscopy and UV-vis spectroscopy are used to characterize the thin films. The spectroscopic analysis revealed a more uniformed crystalline nano-structured surface with fewer structural deffects. As the Mg atom concentration is increased, the results show a linear increment in the band gap of Mg-doped ZnO thin film in comparsion to the pure ZnO nanostructured thin film, as well as there occurs an improvement in...
AIP Conference Proceedings, 2018
European Journal of Physics Education, 2011
The progress of modern cosmology took off in 1917 when A. Einstein published his paper on general... more The progress of modern cosmology took off in 1917 when A. Einstein published his paper on general theory of relativity extending his work of special theory of relativity (1905). In 1922 Alexander Friedmann constructed a mathematical model for expanding Universe that had a big bang in remote past. The experimental evidences could come in 1929 by the pioneering work on nebular red shifts by Edwin Hubble and Milton Humason. Doppler’s red shift for light also comes as a deduction of special theory of relativity which provides a fundamental formalism for observational astronomy. It can also be deduced from cosmological red shift arising from the curvature of space time warp of the Universe depending on the evolution model opted for the Universe. The gravitational red shift comes as a consequence of the principle of equivalence in presence of weak gravitational field which expresses the identity of the gravitational and inertial mass. The gravitation itself is a manifestation of curvature...
AIP Conference Proceedings, 2018
AIP Conference Proceedings, 2020
AIP Conference Proceedings, 2020
AIP Conference Proceedings, 2020
Physics Letters A, 2017
simulation has been performed to study the rupturing process of thin polymer film under strong co... more simulation has been performed to study the rupturing process of thin polymer film under strong confinement. The change in mean square displacement; pair correlation function; density distribution; average bond length and microscopic viscosity, are sampled by varying the molecular interaction parameters such as the strength and the equilibrium position of the bonding, non-bonding potentials and the sizes of the bead. The variation in mean square angular displacement χ θ = [< θ 2 > − < θ > 2 ] fits very well to a function of the type y(t) = A + B * e − t τ. This may help to study the viscous properties of the film and its dependence on different parameters. The ultra thin film annealed at high temperature gets ruptured and holes are created in the film mimicking spinodal dewetting. The pair correlation function and density profile reveal rich information about the equilibrium structure of the film. The strength and equilibrium bond length of finite extensible non-linear elastic potential (FENE) and non-bonding Morse potential have clear impact on microscopic rupturing of the film. The beads show Rouse or repetition motion forming rim like structure near the holes created inside the film. The higher order interaction as dipole-quadrupole may get prominence under strong confinement. The enhanced excluded volume interaction under strong confinement may overlap with the molecular dispersion forces. It can work to reorganize the molecules at the bottom of the scale and can imprint its signature in complex patterns evolved.
Solid State Physics [Working Title], 2020
Though the idea to use numerical techniques, in order to solve complex three-dimensional problems... more Though the idea to use numerical techniques, in order to solve complex three-dimensional problems, has become quite old, computational techniques have gained immense importance in past few decades because of the advent of new generation fast and efficient computers and development of algorithms as parallel computing. Many mathematical problems have no exact solutions. Depending on the complexity of the equations, one needs to use approximate methods. But there are problems, which are beyond our limits, and need support of computers. Ernst Ising published his PhD dissertation in the form of a scientific report in 1925. He used a string of magnetic moments; spin up (+1/2) and spin down (À1/2), and applied periodic boundary conditions to prove that magnetic phase transition does not exist in one dimensions. Lars Onsager, latter, exactly solved the phase transition problem in two dimensions in 1944. It is going to be a century-old problem now. A variety of potential applications of Ising model are possible now a days; classified as Ising universality class models. It has now become possible to solve phase transition problems in complex three-dimensional geometries. Though the area of spinotronics still needs more engagements of computational techniques, its limited use have provided good insights at molecular scale in recent past. This chapter gives a brief introduction to Ising model and its applications, highlighting the developments in the field of magnetism relevant to the area of solid state physics.
Macromolecular Symposia, 2017
The paper deals with the study of coexisting majority and minority components in thin ferromagnet... more The paper deals with the study of coexisting majority and minority components in thin ferromagnetic film which is magnetically stripped by applying external magnetic field in selected regions. There occurs continuous transition from ferromagnetic barriers to a coexisting phase separated region through the formation of a depletion layer. Formation of magnetic barriers, channels and step like structure have been explored. Temperature induced two regime behavior is observedfirst one dominated by the ferroic nature of the film and the second one by the paramagnetic nature of film. Two sizes of lattice in 3 dimensions of 100 Â 100 Â 100 and 200 Â 100 Â 100 are used for Monte Carlo simulation using Ising model with Metropolis algorithm. The spin polarization, average magnetization and spin correlation functions are plotted to reveal the underlying physics. The micrographs of the magnetic barrier and phase separated regions are also shown.
International Journal of Nanoscience, 2019
The results for the case of rupturing of an ultra-thin polymer film confined in a narrow planar g... more The results for the case of rupturing of an ultra-thin polymer film confined in a narrow planar geometry, are presented in this paper. NVT Monte Carlo simulation technique with Glauber kinetics has been used. Periodic boundary conditions are applied along [Formula: see text] and [Formula: see text] directions. Two planar surfaces at separations of [Formula: see text] and 6.75[Formula: see text] are used to confine the film. The lower substrate at [Formula: see text] has square well attractive affinity to the polymer beads, whereas the upper substrate at [Formula: see text] interacts with beads via hard sphere interaction. The properties as-pair correlation function, mean square displacement, density distribution, etc., are sampled for different parameters as pore widths [Formula: see text] and 6.75[Formula: see text], average number densities [Formula: see text] beads/[Formula: see text], 1.78 beads/[Formula: see text] and 1.56 beads/[Formula: see text], surface-film interaction of ...
European Journal Of Physics Education, 2014
This paper presents a brief review of Ising's work done in 1925 for one dimensional spin chain wi... more This paper presents a brief review of Ising's work done in 1925 for one dimensional spin chain with periodic boundary condition. Ising observed that no phase transition occurred at finite temperature in one dimension. He erroneously generalized his views in higher dimensions but that was not true. In 1941 Kramer and Wannier obtained quantitative result for two-dimensional Ising model and successfully deduced the critical temperature of the system. In 1944 Onsager explicitly obtained free energy in zero fields. Though only 1dimensional formula has been derived in this review paper but Monte Carlo simulations results verify the established part of experiment and theory and explore the temperature dependence of magnetic property of thin film in 2D case. The paramagnetic case with spin coupling coefficient J=0 and ferromagnetic cases with J=0.50, 0.75 & 1.0 are studied at temperatures kT=0.20, 0.30, 0.40, 0.50, 0.60, 1.0, 1.5 & 2.0. The change in behavior from Ferro to para is also observed and explained at high T values. I have demonstrated data writing for application purpose by writing number 10 on a thin ferromagnetic tape (i.e. 2D film).
Journal of Materials Science Research, 2015
Nanotechnology is the understanding and control of matter at the diemnsions ranging between 1-100... more Nanotechnology is the understanding and control of matter at the diemnsions ranging between 1-100 nm. One nanometer is one billionth of a meter. Nanotechnology involves manipulation of atoms, imaging, measuring and modelling at nano scale. Its potentials were first highlighted by Richard Feynman in the American Physical Scociety meeting in 1959. Though, he did not coin the world nanotechnology himself but he explored the possiblities of functional materials at the bottom of the scale. In last two decades this technology has been commercialized to great extent and gaining importance day by day influencing the economies of different countries and henceforth enforcing the policy makers to address the issues like environment, health and safety. Governments are regularisaing and monitoring its research, uses, applications and technology transfer which includes intelluctaul property rights. This paper addresses the dimensions and trends of nanotechnology covering economic aspects. The paper is focussed on the changes in the functional properties of nanomaterials as physical, chemical, optical, electronic, electrical, magnetic etc. in comparision to those of the bulk of material. It has been discussed how the basic and advance research in nanoscience could be explotiedfor making technologies for its commercial and industrial applications for the benefit and safety of the soceity. Thin film magnetism is demonstrated using Monte Carlo simulation method. Experimental synthesis of some of the nanorods and qunatum dots are also discussed.
Advances in Condensed Matter Physics, 2011
The emerging structures in spinodal dewetting of thin nano films and spinodal decomposition of bi... more The emerging structures in spinodal dewetting of thin nano films and spinodal decomposition of binary mixtures are found to be similar with certain differences attributed to the nonlinearities inherent in the wetting forces. This paper deals with the technological aspects of the spinodal processes by giving a brief account of the theory and to correlate the two phenomena termed as spinodal dewetting of thin nanofilms and surface-directed phase separation. The MC simulation micrographs at early stage of spinodal dewetting of a (linear) polymer film confined between two hard walls (using FENE potential between the beads on same chain and Morse potential between inter and intra chain beads) show similarities with surface-directed phase separation (using metropolis algorithm) in creation of holes. The spinodal dewetting is also criticized on the basis of global minimization of free energy emerging from dipole-quadrupole interactions. A novel molecular scale-driving mechanism coming from...
Applied Nanoscience, 2012
The spinodal decomposition has got fresh attraction in the past few decades with the advent of ne... more The spinodal decomposition has got fresh attraction in the past few decades with the advent of new computational problems under very thin geometries. The nanodrops evolve in the phase separation process. The phase separation process itself interplays with the wetting forces and give rise to structures of importance for a wide range of technological applications from spherical nanomagnetic domains to magnetic strips. MC simulation programs for 2D and 3D cases have been written for surface directed phase separation (using metropolis algorithm) to observe the spatial correlation varying with time, which shows a polynomial fitting behavior for 2D case and follow a peculiar trend with time specially, in early stages of evolution indicating a colossal behavior. The two point correlations (Pearson's linear xy correlation function) if evaluated in 3D case do not show any important oscillatory behavior but instead confirm for the two regimes as phase separation or mixing and the wetting ones. The correct generalization of xy correlation as xyz correlation in 3D case (i.e., product of the three moments) does not seem to be a reliable one because it moves to six to seven decimal places, thus comes out at the cost of loss in confidence limit. Thus, the 3D simulation confirm the two regime behavior indicating that the same colossal behavior of 2D case can exist in real 3D thin film of random binary mixture. Thus, the colossal behavior as obtained for the case of 2D problem is retained, and this may indicate for a quantized or discrete colossal behavior for certain set of composition and interface parameters for definite but small time periods. The corresponding density profiles are also plotted to confirm the distributions of the two components. Such computational studies may help in developing theoretical models for the observed phenomena and to search out for new events at the very bottom of the scale.
International Journal of Nanoscience, 2011
Bridge-like structures have been reported in recent studies for a binary mixture with square well... more Bridge-like structures have been reported in recent studies for a binary mixture with square well fluids in 2D and 3D using different techniques. In this paper, we present our NVT simulation results in 3D with symmetric additive water and oil-like molecules. We use Dirac's delta function defined using theta step function for evaluating pressure components and surface tension values. Our investigation reveals that though 3D NVT MC results are in qualitative agreement with the published results showing all the structures as bridge-like, complete wetting of the walls by the preferred component and micelle structures but the critical parameters as surface attraction strength significantly alter to lower values for PW and CW cases in comparison to the 2D MD cases. We have studied cases with pore width as H = 6.0, 8.0, and 10.0 at T = 0.70, 0.80, and 0.90 for εAB = 0.0, 0.25, 0.50, and 1.0. For all of the bridge cases ε Wall -A = -0.50 and λ wall -A = 1.0. For fluid–fluid interaction ...
Applied Nanoscience, 2012
To extend the work of binary fluid mixtures and their associated bridge-like structures, the adso... more To extend the work of binary fluid mixtures and their associated bridge-like structures, the adsorption of gas-like molecules (interacting via hard-sphere potentials) on self-assembled fluid channels was examined. We examined the morphological evolution of an initial random binary mixture under confinement of chemically patterned substrates with strong, long-range preferential attraction to the pure square-well component. Gas-like molecules were presumed to have a weak attraction to the square-well fluid. The morphology and corresponding density profiles revealed the underlying chemical and physical adsorption of gas-like molecules to off-strip voids and to the interface of the self-assembled fluid channels. The entropic effects drive the non-interaction hard-sphere molecules to assemble or reorganize in the voids left between the selfassembled square-well fluids. Such studies can help in the study of formation of nano-liquid structures and enhanced adsorption of gas-like molecules for storage purposes.
Molecular Physics, 2009
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Papers by Satya Pal Singh