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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. Source


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. Source


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. Source


Cinthia A.J.,Nmssvn College | Priyanga G.S.,Nmssvn College | Rajeswarapalanichamy R.,Nmssvn College | Iyakutti K.,SRM University
Journal of Physics and Chemistry of Solids | Year: 2015

The structural, electronic and mechanical properties of alkaline earth metal oxides MO (M=Be, Mg, Ca, Sr, Ba) in the cubic (B1, B2 and B3) phases and in the wurtzite (B4) phase are investigated using density functional theory calculations as implemented in VASP code. The lattice constants, cohesive energy, bulk modulus, band structures and the density of states are computed. The calculated lattice parameters are in good agreement with the experimental and the other available theoretical results. Electronic structure reveals that all the five alkaline earth metal oxides exhibit semiconducting behavior at zero pressure. The estimated band gaps for the stable wurtzite phase of BeO is 7.2 eV and for the stable cubic NaCl phases of MgO, CaO, SrO and BaO are 4.436 eV, 4.166 eV, 4.013 eV, and 2.274 eV respectively. A pressure induced structural phase transition occurs from wurtzite (B4) to NaCl (B1) phase in BeO at 112.1 GPa and from NaCl (B1) to CsCl (B2) phase in MgO at 514.9 GPa, in CaO at 61.3 GPa, in SrO at 42 GPa and in BaO at 14.5 GPa. The elastic constants are computed at zero and elevated pressures for the B4 and B1 phases for BeO and for the B1 and B2 phases in the case of the other oxides in order to investigate their mechanical stability, anisotropy and hardness. The sound velocities and the Debye temperatures are calculated for all the oxides using the computed elastic constants. © 2014 Elsevier Ltd. Source


Kanagaprabha S.,Kamaraj College | Asvinimeenaatci A.T.,Nmssvn College | Rajeswarapalanichamy R.,Nmssvn College | Iyakutti K.,Madurai Kamaraj University
Physica B: Condensed Matter | Year: 2012

First principles calculation were performed using Vienna ab-initio simulation package within the frame work of density functional theory (DFT) to understand the electronic properties of magnesium hydride. At normal pressure, the most stable structure of MgH2 is rutile type with a wide band gap of 3.52 eV, which agrees well with the available data. A pressure induced semi-conductor to metallic transition at a pressure of 92.54 GPa is predicted. Our results indicate a sequence of pressure induced structural phase transition in MgH2. The obtained sequence of phase transition was α→γ→β→δ→ε at a pressure of 0.37 GPa, 3.89 GPa,7.23 GPa and 11.26 GPa, respectively. Thus our results indicate that MgH2 is one of the best hydrogen storage material and the maximum storage capacity achieved was 7.7%. © 2011 Elsevier B.V. All rights reserved. Source

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