i) 2017 - 37 Documents

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Author: search.filters.author.Balavijayalakshmi, J

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    CARICA PAPAYA PEEL MEDIATED SYNTHESIS OF SILVER NANOPARTICLES AND ITS ANTIBACTERIAL ACTIVITY AGAINST HUMAN PATHOGENS
    (ScienceDirect, 2017-09-28) Balavijayalakshmi, J; Ramalakshmi, V
    Metallicnanoparticlesaretraditionallysynthesizedbywetchemicaltechniques,inwhichthechemicalsusedarequiteoftentoxicandflammable.Ripecaricapapayapeelisfoundtobeasuitablesourceforgreensynthesisofsilvernanoparticles.Inthepresentwork,acosteffectiveandenvironmentalfriendlytechniqueforthegreensynthesisofsilvernanoparticlesfrom1mMsilvernitrate(AgNO3)solutionthroughtheextractofripeCaricapapayapeelofvariousconcentrations(5ml,10ml,15ml,20ml,25ml)isdescribed.ThesynthesizedsilvernanoparticlesarecharacterizedbyusingtheUV–visabsorptionspectroscopy,FT IR,XRD,SEMandTEM.Theformationofsilvernanoparticlesisconfirmedbysurfaceplasmonresonance,determinedbyUV–visspectraat400–435nm.Theshiftintheabsorptionbandsandvariationinthecalculatedopticalbandgapsforthevariousconcentrationsofpapayapeelsextractsarealsoobserved.TheFT-IRspectrarevealthatanincreaseintheconcentrationofthepapayapeelextractshiftsthebandstohigherwavelengths.TheaveragecrystallitesizeforvariousconcentrationsofpapayapeelextractisobservedfromXRDspectralanalysisandisfoundtobearound16–20nm,whichisingoodagreementwiththeTEManalysis.TheSEManalysisshowsthesphericalstructureofthesilvernanoparticleswithsomeagglomerationforhigherconcentrationsofpapayapeelextract.ThesynthesizedsilvernanoparticlesshowgoodantibacterialactivityagainsthumanpathogenssuchasEscherichiacoliandStaphylococcusaureusandithasmanymedicalapplications
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    EFFECT OF COBALT SUBSTITUTION ON STRUCTURAL AND MAGNETIC PROPERTIES OF MAGNESIUM FERRITE NANOPARTICLES
    (Springer Link, 2017-05-04) Balavijayalakshmi, J; Sudha, T
    Cobalt substituted magnesium ferrite (Mg(1−x)CoxFe2O4, where x = 0.2, 0.4, 0.6 and 0.8) nanoparticles are prepared by co-precipitation method and samples are annealed at 600 °C. The synthesized nanoparticles are characterized using FT-IR spectral analysis, X-ray diffraction (XRD) analysis, Scanning Electron Microscopy (SEM) analysis, Transmission Electron Microscopy (TEM ) analysis and Vibrating Sample Magnetometer (VSM) analysis. The FT-IR spectra show main absorption bands are shifted to higher values as the concentration of cobalt increases. The average nano-crystallite sizes are found to be in the range 7–9 nm. The SEM micrographs show uniformly distributed granular like structure. TEM indicate the presence of rectangular shaped nanoparticles. The magnetic properties of these samples are studied using Vibrating Sample Magnetometer (VSM). As the magnetic properties are enhanced due to the cobalt substitution the synthesized samples can be used as a gas sensor.
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    IMPACT OF ANNEALING ON STRUCTURAL AND MAGNETIC PROPERTIES OF MANGANESE CO-DOPED MAGNESIUM-COBALT FERRITE NANOPARTICLES
    (Springer Link, 2017-05-04) Balavijayalakshmi, J; Annie Josphine, C
    Manganese co-doped magnesium-cobalt ferrite nanoparticles (Mg0.4Co0.4Mn0.2Fe2O4) are synthesized by co-precipitation method and are annealed at 130, 600 and 900 °C. The synthesized nanoparticles are characterized using X-ray diffraction (XRD) analysis, FT-IR spectral analysis, Scanning Electron Microscopy (SEM) analysis, Transmission Electron Microscopy (TEM ) analysis and Vibrating Sample Magnetometer (VSM ) analysis. The crystallite size is found to be 17 and 19.6 nm for the samples annealed at 600 and 900 °C respectively. The crystallite size and lattice constant increases as the samples are annealed at higher temperatures. FT-IR analysis confirms the characteristic absorption bands at 590 and 546 cm−1 for tetrahedral sites and 416 cm−1 for octahedral sites. SEM analysis shows uniformly distributed spherical shaped nanoparticles. The microstructure and particle size are analyzed by TEM analysis. The saturation magnetization, remanent magnetization and coercivity increases due to the inclusion of manganese and as the annealing temperature increases. These samples can be used for gas sensing applications.