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Kavitha B.,Kongunadu Arts and Science College | Dhanam M.,Kongunadu Arts and Science College
Electronic Materials Letters | Year: 2013

Films of Cu(InAl)Se2 were deposited onto glass substrates by SILAR (successive ionic layer adsorption and reaction) method. All the deposited films were found to be polycrystalline in nature exhibiting the chalcopyrite structure with the crystallite orientation along (112), (220/204) and (116/312) directions. The photocurrent was found to increase with increase in film thickness and also with increase of light intensity. Photocurrent spectra showed a peak related to the band-to-band transition. The spectral response of Cu(InAl)Se2 thin films was studied by allowing the radiation to pass through a series of interference filters in the wavelength range 300 to 1200 nm. Films of higher thickness exhibited higher photosensitivity while lower thickness films exhibited moderate photosensitivity. Cu(InAl)Se2-based solar cells with different types of buffer layers such as CdS, CdS:Cu, CdS:In were fabricated. The current and voltage were measured using an optical power meter and an electrometer and the fabricated solar cells were illuminated using 100 mW/cm2 white light under AM1 conditions. © 2013 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.


Mageshwari K.,Kongunadu Arts and Science College | Sathyamoorthy R.,Kongunadu Arts and Science College
Materials Science in Semiconductor Processing | Year: 2013

Bismuth sulfide (Bi2S3) nanocrystalline thin films were deposited on glass substrate by a simple and low-cost thioglycolic-assisted successive ionic layer adsorption and reaction method, using bismuth acetate and thioacetamide as cationic and anionic precursors respectively. Influence of cationic concentration on the structural, optical and electrical properties of Bi2S3 thin films were investigated. X-ray diffraction pattern revealed that the prepared Bi2S3 thin films are polycrystalline with orthorhombic structure. The surface morphology of Bi 2S3 thin films examined by atomic force microscopy showed cluster like morphology, and having small hillocks of fairly uniform distribution. Optical studies showed a direct band-to-band transition, and the estimated optical band gap decreases from 1.81 eV to 1.25 eV with the increase in cationic concentration from 0.01 M to 0.03 M. Electrical resistivity measurements by four probe technique revealed negative temperature coefficient of resistance, which confirms the semiconducting nature of Bi2S 3 thin films. The activation energy of Bi2S3 thin films was found to decrease from 0.059 eV to 0.022 eV with the increase in cationic concentration from 0.01 M to 0.03 M, which is attributed to improved grain size and reduction in the defect levels. © 2012 Elsevier Ltd.


Mageshwari K.,Kongunadu Arts and Science College | Sathyamoorthy R.,Kongunadu Arts and Science College
Journal of Materials Science and Technology | Year: 2013

In the present work, flower-like CuO nanostructures were synthesized by reflux condensation method without using any surfactants or templates. Structural analysis by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman studies revealed the formation of highly crystalline single phase CuO, exhibiting monoclinic structure. Morphological analysis by field emission scanning electron microscopy (FESEM) showed flower-shaped CuO hierarchical architecture made up of interpenetrating self-assembled nanosheets. Optical analysis by UV-Vis diffused reflectance spectra (DRS) exhibited considerable blue-shift in the optical band gap due to quantum confinement effect. Photoluminescence (PL) spectrum showed both UV as well as visible emissions. The antibacterial activity of flower-shaped CuO nanostructures were tested against gram-positive ( Bacillus subtilis, Bacillus thuringiensis) and gram-negative ( Salmonella paratyphi, Salmonella paratyphi-a, Salmonella paratyphi-b, Escherichia coli and Pseudomonas aeruginosa) bacteria. Also, the antifungal activity of CuO was investigated against Aspergillus niger, Rhizopus oryzae, Aspergillus flavus, Cladosporium carrionii, Mucor, Penicillium notatum and Alternaria alternata. Results demonstrate that the flower-shaped CuO nanostructures act as an effective antimicrobial agent against pathogenic bacteria and fungi. © 2013.


Nirmala M.,Kongunadu Arts and Science College | Anukaliani A.,Kongunadu Arts and Science College
Physica B: Condensed Matter | Year: 2011

ZnO nanopowders doped with 5 and 10 at% cobalt were synthesized and their antibacterial activity was studied. Cobalt doped ZnO powders were prepared using dc thermal plasma method. Crystal structure and grain size of the particles were characterized by X-ray diffractometry and optical properties were studied using UVvis spectroscopy. The particle size and morphology was observed by SEM and HRTEM, revealing rod like morphology. The antibacterial activity of undoped ZnO and cobalt doped ZnO nanoparticles against a Gram-negative bacterium Escherichia coli and a Gram-positive bacterium Bacillus atrophaeus was investigated. Undoped ZnO and cobalt doped ZnO exhibited antibacterial activity against both E. coli and Staphylococcus aureus but it was considerably more effective in the cobalt doped ZnO. © 2010 Elsevier B.V. All rights reserved.


Nirmala M.,Kongunadu Arts and Science College | Anukaliani A.,Kongunadu Arts and Science College
Materials Letters | Year: 2011

Antibacterial activity of Transition metals (Mn, Co) doped ZnO nanopowders prepared by a DC thermal plasma method against Escherichia coli and Staphylococcus aureus are investigated. The phase and morphology studies have been carried out by X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. Allthe samplesofthe present investigation are foundtohave hexagonal wurtzite structure and crystallite sizes are found to vary from 25 nm to 30 nm. Our bacteriological study showed the enhanced antibacterial activity of transition metals doped ZnO nanoparticles than undoped ZnO indicating the great potential of ZnO nanoparticles in relevant clinical and biomedical applications. © 2011 Elsevier B.V. All rights reserved.


Mageshwari K.,Kongunadu Arts and Science College | Sathyamoorthy R.,Kongunadu Arts and Science College
Materials Science in Semiconductor Processing | Year: 2013

We report a facile and low-cost successive ionic layer adsorption and reaction method to synthesize nanocrystalline CuO thin films. Influence of deposition cycles on the physical properties of nanocrystalline CuO thin films was investigated. X-ray diffraction studies show that all the films exhibit polycrystalline nature with monoclinic crystal structure. Fourier transform infrared spectroscopy and Raman studies confirmed the formation of single phase CuO wherein the characteristic vibrational mode of CuO was identified. Scanning electron microscopy studies revealed the formation of sporadic growth of rod-shaped elongated particles. Both the structural and surface properties of CuO thin films were improved with the increase in the deposition cycles as a result of which the optical absorption edge of CuO shift towards longer wavelength, and the optical band gap energy decreases from 2.48 eV to 2.31 eV. The room-temperature photoluminescence spectrum showed blue emission band centered at 468 nm, attributed to the near-band-edge emission of CuO due to Burstein-Moss effect. © 2012 Elsevier Ltd.


Sathyamoorthy R.,Kongunadu Arts and Science College | Mageshwari K.,Kongunadu Arts and Science College
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2013

In this work, hierarchical CuO micropeony was synthesized by an environmentally benign reflux condensation approach without using any surfactant or templates. X-ray diffraction (XRD) analysis revealed the formation of CuO exhibiting monoclinic crystal structure. Fourier transform infrared spectroscopy (FTIR) further confirmed the formation of single phase CuO. Scanning electron microscopy (SEM) analysis showed that the hierarchical CuO architecture is composed of numerous interpenetrating nanosheets that radiated from the center to form floral pattern with a diameter of 1-2 μm. Photoluminescence (PL) spectra of CuO exhibited both UV and visible emissions. The photocatalytic activity of hierarchical CuO microsphere was evaluated by monitoring the photodegradation of methyl orange dye while the antibacterial activity was studied against gram-positive and gram-negative bacteria's. Results demonstrated that CuO hierarchical architecture possesses good photocatalytic as well as antibacterial activity. © 2012 Elsevier B.V. All rights reserved.


Kungumadevi L.,Kongunadu Arts and Science College | Sathyamoorthy R.,Kongunadu Arts and Science College
Materials Research Bulletin | Year: 2013

The face-centered cubic PbTe micro-needles were synthesized by a simple aqueous chemical reaction between lead acetate and tellurium in NaOH solution in the presence of Na2HPO4 as reducing reagent at low temperature under atmospheric pressure without any additional surfactants or templates. Micro structural analyses show that these micro-needles are in the range of 90-130 nm in diameter with length ∼2 μm. Electrical resistivity of prepared PbTe micro-needles was found to be 14-33 Ohm-cm. The optical absorption spectrum of PbTe micro-needles shows large blue-shift (∼1.26 eV) with respect to those of the bulk counterpart (0.32 eV) due to quantum confinement of charge carriers, which is consistent with the blue shift of the band emission peak in the photoluminescence spectrum. © 2013 Elsevier Ltd.


Kungumadevi L.,Kongunadu Arts and Science College | Sathyamoorthy R.,Kongunadu Arts and Science College
Advanced Powder Technology | Year: 2013

The present study investigates the properties of mechanically compacted pellets of nanosized lead telluride powders synthesized by using ethylene glycol as solvent and PVP as surfactant. XRD analysis indicates the formation of PbTe nanocrystals which exhibit both cubic and orthorhombic phases. Morphological study reveals that the prepared PbTe nanocrystals have disk-like shape. Electrical analysis reveals that the electrical conductivity of PbTe nanocrystals can be enhanced by the formation of nanodisks. Optical absorption and PL results show a large blue-shift which implies that the prepared PbTe nanodisks show strong quantum confinement effect. The possible formation mechanism of the PbTe nanodisks was also discussed. © 2012 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder.


Remia K.M.,Kongunadu Arts and Science College | Logaswamy S.,Kongunadu Arts and Science College
Indian Journal of Natural Products and Resources | Year: 2010

Mosquitoes are the most important single group of insects in terms of public health. They transmit a number of diseases, such as malaria, filariasis, dengue fever, chikungunya, Japanese encephalitis, etc. causing millions of deaths every year. The application of easily degradable plant compounds is considered to be one of the safest methods to control insect pests and vectors as an alternative source for the synthetic pesticides. A study was made to monitor the effect of plant extracts on different instars of larvae and pupae of mosquito vector Aedes aegypti. Bio-assay was made using the solvent acetone to find out the median lethal concentration (LC50). Plants, like Lantana camara Linn., Catharanthus roseus G. Don which possess insecticidal properties, are seemed to be better vector control agents than the synthetic xenobiotics.

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