• S Radha

      Articles written in Bulletin of Materials Science

    • One-pot size and shape controlled synthesis of DMSO capped iron oxide nanoparticles

      Debanjan Guin Sunkara V Manorama S Radha A K Nigam

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      We report here the capping of iron oxide nanoparticles with dimethyl sulfoxide (DMSO) to make chloroform soluble iron oxide nanoparticles. Size and shape of the capped iron oxide nanoparticles are well controlled by simply varying the reaction parameters. The synthesized nanocrystallites were characterized by thermal analysis (TG–DTA), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) for evaluating phase, structure and morphology. 1H NMR spectra of the synthesized samples confirm DMSO, and the capping of DMSO on the ferrite samples. Shift of the S=O stretching frequency in Fourier transformed infrared (FTIR) spectra indicates that the bonding between DMSO and ferrite is through an oxygen moiety. The magnetic measurements of all the synthesized samples were investigated with a SQUID magnetometer which shows that the magnetic properties are strongly dependent on the size as well as shape of the iron oxide.

    • Electronic spectra of anions intercalated in layered double hydroxides

      S Radha P Vishnu Kamath

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      Transition metal complexes intercalated in layered double hydroxides have a different electronic structure as compared to their free state owing to their confinement within the interlayer gallery. UV–Vis absorptions of the intercalated complex anions show a significant shift as compared to their free state. The ligand to metal charge transfer transitions of the ferricyanide anion show a red shift on intercalation. The ferrocyanide ion shows a significant blue shift of 𝑑–𝑑 bands due to the increased separation between 𝑡2g and 𝑒g levels on intercalation. MnO$^{-}_{4}$ ion shows a blue shift in its ligand to metal charge transfer transition since the non-bonding 𝑡1 level of oxygen from which the transition arises is stabilized.

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