Nmssvn College

Madurai, India

Nmssvn College

Madurai, India

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Amudhavalli A.,Nmssvn College | Rajeswarapalanichamy R.,Nmssvn College | Iyakutti K.,SRM University
Journal of Alloys and Compounds | Year: 2017

The search for stable half-metallic ferromagnetic materials remains a high priority in condensed matter Physics. Ab initio calculations are performed using density functional theory to analyze the structural phase stability, electronic structure, mechanical and magnetic properties of Mn based half Heusler alloys XYZ (X = Ir, Pt, Au; Y = Mn; Z = Sn, Sb) for three different phases namely α, β and γ phases of C1b crystal structure. This work aims to identify the ferromagnetic and half-metallic behavior of XYZ (X = Ir, Pt, Au; Y = Mn; Z = Sn, Sb) half Heusler alloys. To accomplish this, density functional theory (DFT) with generalized gradient approximation formulated by Perdew, Burke and Ernzerhof (GGA-PBE) and the Hubbard formalism (GGA-PBE + U) are used to describe the strong correlations present in these alloys. Among the considered phases, α-phase is found to be the lowest energy phase for IrMnSn, IrMnSb, PtMnSn, PtMnSb, AuMnSn and AuMnSb at normal pressure. A pressure-induced structural phase transition is observed in IrMnSn, IrMnSb, PtMnSn, PtMnSb, AuMnSn and AuMnSb at the pressures of 62.1 GPa, 47.8 GPa, 26.1 GPa, 25.3 GPa, 23.7 GPa and 14.0 GPa respectively. The electronic structure reveals that these materials are metals at normal pressure whereas half metals at high pressure. The magnetic moments for these half Heusler alloys in all the three different phases (α, β and γ) are estimated. © 2017 Elsevier B.V.


Asvini Meenaatci A.T.,Nmssvn College | Rajeswarapalanichamy R.,Nmssvn College | Iyakutti K.,Noorul Islam University
Thin Solid Films | Year: 2012

The structural, elastic, and electronic properties of molybdenum nitride are investigated by first principles calculation with density functional theory. The obtained hexagonal WC structure is energetically the most stable structure at an ambient pressure. A pressure induced structural phase transition from hexagonal WC to cubic NaCl structure is predicted. The estimated superconducting transition temperature (Tc) of molybdenum nitride is 14.0037 K. As pressure increases the superconducting transition temperature also increases. © 2012 Elsevier B.V.


Asvini Meenaatci A.T.,Nmssvn College | Rajeswarapalanichamy R.,Nmssvn College | Iyakutti K.,SRM University
Solid State Sciences | Year: 2013

The electronic, structural, mechanical and superconducting properties of group VB mononitrides are investigated by means of first principles calculation based on density functional theory with generalized gradient approximation. The calculated ground state properties are in good agreement with previous experimental and theoretical results. Among the three crystallographic structures that have been investigated, the hexagonal WC phase is found to more stable than the cubic ones. Under high pressure, a series of structural phase transition from WC → NaCl → CsCl phase is also predicted in VN, NbN and TaN. The calculated elastic constants indicate that all the three nitrides are mechanically stable at ambient pressure. The estimated Zener ratio and linear compressibility coefficients Kc/Ka reveals that these materials exhibit elastic anisotropy. The estimated superconducting transition temperature (Tc) values as a function of pressure for VN, NbN and TaN are 35.5, 37.5 and 30.5 K respectively. © 2013 Elsevier Masson SAS. All rights reserved.


Rajeswarapalanichamy R.,Nmssvn College | Asvini Meenaatci A.T.,Nmssvn College | Iyakutti K.,SRM University
Ceramics International | Year: 2014

The structural, electronic, elastic and magnetic properties of three rare earth nitrides (RENs: RE=Gd, Dy, Ho) are investigated by first principles calculation using Vienna ab-initio simulation code (VASP). At ambient pressure all the three nitrides are stable in the ferromagnetic state (FM) with cubic NaCl(B1) structure. The calculated lattice parameters are in good agreement with experimental and other theoretical values. Electronic structure reveals that these materials are half metallic ferromagnets at normal pressure. A pressure induced structural phase transition from NaCl to wurtzite phase in GdN at 18.2 GPa and from NaCl to CsCl phase in DyN at 104 GPa and HoN at 138 GPa is also predicted. The half metallicity has been retained in GdN, DyN and HoN even after the phase transition but it vanishes at 73.18 GPa, 118 GPa and 141 GPa respectively. Ferromagnetism is quenched in all the three nitrides at a pressure of 252 GPa (GdN), 242 GPa (DyN) and 236.7 GPa (HoN). © 2013 Elsevier Ltd and Techna Group S.r.l.


Pushpam S.,Thiagarajar College of Engineering | Pushpam S.,Nmssvn College | Kottaisamy M.,Thiagarajar College of Engineering | Ramakrishnan V.,Thiagarajar College of Engineering
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

The dependence of fluorescence emission of 2-amino-3-bromo-1,4- naphthoquinone on titanium dioxide (TiO2) in methanol has been investigated. The increase in TiO2 concentration causes a decrease in the fluorescence intensity of 2-amino-3-bromo-1,4-naphthoquinone. A linear Stern-Volmer plot in this study indicates the presence of dynamic quenching. The quenching and association constants have been calculated. The quenching process is due to the electron transfer from 2-amino-3-bromo-1,4-naphthoquinone to TiO2. © 2013 Elsevier B.V. All rights reserved.


Mangaiyarkkarasi J.,NMSSVN College | Saravanan R.,The Madura College
Journal of Materials Science: Materials in Electronics | Year: 2016

In this work, we report the influences of Ce doping on structural, morphological, optical and charge derived properties of BaTi1−xCexO3 (x = 0.02, 0.04, 0.06 & 0.08) ceramic synthesized by high temperature solid state reaction method. This ceramic has been characterized by powder X-ray diffraction (PXRD), UV–visible spectrometry, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Lattice parameters were determined through the profile refinement technique using PXRD data. Charge density redistribution and bonding nature of the grown systems are analyzed by maximum entropy method (MEM). Incorporation of rare earth ion Ce into the BaTiO3 lattice enhances the ionic nature between Ba and O ions and decreases the ionic nature between Ti and O ions, revealed from the qualitative and quantitative analysis by MEM. Optical band gap values are estimated for the prepared samples from UV–Vis data. Formation of aggregated particles with low porosity is observed from SEM micrographs. The chemical compositions of the prepared samples are further confirmed by EDS spectral analysis. © 2016 Springer Science+Business Media New York


Saravanan R.,The Madura College | Mangaiyarkkarasi J.,NMSSVN College
Journal of Materials Science: Materials in Electronics | Year: 2016

The Ba1−xSrxTiO3 perovskites (abbreviated as BST, x = 0.2, 0.4 and 0.6) have been synthesized by high temperature solid state reaction technique. The influences of Sr doping on the morphology, electron density distribution and optical properties at the lattice sites of BaTiO3 have been investigated by X-ray diffraction, scanning electron microscopy and UV–visible spectroscopy. With the increase in Sr content, the lattice parameter, cell volume, density and the grain sizes are found to be reduced. The incorporation of Sr content into the BaTiO3 lattice decreases the ionic nature of the bonding between Ti and O ions and increases ionic nature between Ba and O ions and the energy gap measurements indicate the reduction in insulating property of the grown samples. The stoichiometry of the samples was further confirmed by energy dispersive X-ray spectroscopy. © 2015, Springer Science+Business Media New York.


Malathy P.,Nmssvn College | Vignesh K.,P.A. College | Rajarajan M.,P.A. College | Suganthi A.,P.A. College
Ceramics International | Year: 2014

Transition metal (M=Ni and Zn) doped Bi2O3 nanoparticles were prepared by the precipitation method to enhance the photocatalytic activity of Bi2O3. The as-prepared nanoparticles were characterized by different techniques such as powder-X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (UV-vis-DRS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and photoluminescence (PL) techniques. The photocatalytic activity was evaluated by the degradation of malachite green (MG) dye under visible light irradiation. The results revealed that Ni doped Bi2O3 (Ni-Bi 2O3) exhibited higher photocatalytic activity when compared to that of other photocatalysts. A set of optimized conditions such as pH, catalyst concentration and initial dye concentration on the photodegradation of MG were investigated in detail. © 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.


Benial A.M.F.,NMSSVN College | Dhas M.K.,NMSSVN College | Jawahar A.,NMSSVN College
Applied Magnetic Resonance | Year: 2011

The mobility studies on 14N-labeled TEMPONE, TEMPO, carbamoyl-PROXYL, carboxy-PROXYL in high viscous liquid were carried out on a 300 MHz electron spin resonance (ESR) spectrometer. The ESR parameters, such as a line width, signal intensity ratio, g-factor, hyperfine coupling constant and correlation time, were determined. The line width broadening increases twofold in high viscous samples of 14N-labeled carbamoyl-PROXYL and carboxy-PROXYL, but this line broadening is negligibly small in the high viscous sample (85% glycerol) of 14N-labeled TEMPO. The correlation time also increases (~30 times) in the high viscous sample (85% glycerol) of 14N-labeled carbamoyl-PROXYL and carboxy-PROXYL, but there is no considerable increase in the high viscous sample of 14N-labeled TEMPO. TEMPONE has the narrowest line width and is also highly sensitive to viscosity. The correlation time increases (~13 times) in the high viscous sample (85% glycerol) of 14N-labeled TEMPONE. Therefore, this study reveals that the 14N-labeled TEMPONE radical is the most suitable spin probe for in vivo studies in high viscous biological fluids. © 2011 Springer-Verlag.


Asvini Meenaatci A.T.,Nmssvn College | Rajeswarapalanichamy R.,Nmssvn College | Iyakutti K.,Madurai Kamaraj University
Physica B: Condensed Matter | Year: 2011

First-principles calculation was performed using tight-binding LMTO method with local density approximation (LDA) and atomic sphere approximation (ASA) to understand the electronic properties of rhenium nitride. The equilibrium geometries, the electronic band structure, the total and partial DOS are obtained under various pressures and are analyzed in comparison with the available experimental data. The most stable structure of ReN is NiAs like structure. Our results indicate that ReN can be used as a super-hard conductor. We estimated the average electronphonon coupling constant to be 1.65 and superconducting transition temperature (Tc) is 5.1 K. The T c value increases with the increase in pressure. © 2011 Elsevier B.V. All rights reserved.

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