Faculty Publications

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Author: search.filters.author.Udayashankar, N.K.Subject: search.filters.subject.Room temperature

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    Crystal structure of semiorganic antimony thiourea bromide monohydrate crystals: a redetermination
    (2009) Upadhya, M.K.; Udayashankar, N.K.
    The growth of antimony thiourea bromide monohydrate (ATBM) single crystals by evaporation technique at room temperature is reported here. Antimony thiourea bromide monohydrate crystallizes in the orthorhombic space group Cmca with unit cell parameters a = 12.320(7) A, b = 11.668(7) A, c = 18.615(11), and z = 8. The structure has been solved by direct methods and refined to a final R value of 0.0239.
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    Electron irradiation effects on optical properties of semiorganic antimony thiourea bromide monohydrate single crystals
    (2010) Mahesha Upadhya, K.; Udayashankar, N.K.
    Antimony thiourea bromide monohydrate (ATBM) single crystals were grown by solution growth technique at room temperature for the first time. The UVvis, FT-IR and fluorescence spectra were recorded and electron irradiation effects on these properties were studied. The optical absorption edge of the UVvis spectrum shifts towards lower wavelength with the increase of irradiation. The fluorescence quantum yield is increased for electron irradiated ATBM crystals. The FT-IR analysis shows that the water of crystallization is weakly bonded in as-grown and electron irradiated ATBM crystals. © 2010 Elsevier B.V. All rights reserved.
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    Synthesis, microhardness, FT-IR, and thermal decomposition of semiorganic antimony thiourea bromide monohydrate single crystals
    (2012) Mahesha Upadhya, K.; Udayashankar, N.K.
    Antimony thiourea bromide monohydrate (ATBM) single crystals were grown by a solution growth technique at room temperature. Microhardness studies on the grown crystal were carried out using the Vickers microhardness tester to estimate the mechanical strength of the crystal. The FT-IR analysis ascertains the presence of a metal-sulphur bond in ATBM crystals. The thermal decomposition of ATBM crystals was investigated by means of thermogravimetric analysis. © Springer Science+Business Media, LLC 2011.
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    Electron irradiation effects on optical properties of semiorganic antimony thiourea tetra chloride single crystals
    (2012) Mahesha Upadhya, K.; Udayashankar, N.K.; Ganesh, S.
    Antimony thiourea tetra chloride single crystals were grown by solution growth technique at room temperature. The UV-visible, fourier transform infrared and fluorescence spectra were recorded and electron irradiation effects on these properties were studied. The optical absorption edge of the UV-visible spectrum slightly shifts towards longer wavelength with the increase of irradiation dose. The fluorescence quantum yield is decreased for electron irradiated antimony thiourea tetra chloride crystals. The presence of functional group of the as-grown and electron irradiated complex was confirmed by fourier transform infrared spectral study. © 2012 Elsevier B.V. All rights reserved.
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    Fabrication and high-temperature structural characterization study of porous anodic alumina membranes
    (2012) Choudhari, K.S.; Sudheendra, P.; Udayashankar, N.K.
    Porous anodic alumina (PAA) membranes with highly ordered array of nanopores were prepared by twostep anodization process. Studies on structural and thermal properties and the thermal stability of the prepared PAA membranes were carried out. Investigation using scanning electron microscopy, atomic force microscopy, X-ray diffraction, thermal analysis and infrared spectroscopy was performed on the prepared PAA membranes at room temperature and in the temperature range 600-1,400 °C. The as-prepared PAA membranes revealed the amorphous nature. Polycrystalline PAA membranes were obtained by annealing carried out at different temperatures. Annealing study confirmed that the heat treatment transformed the amorphous PAA membranes to their crystalline phases, namely, ?-alumina at about 870 °C and then to ?-alumina around 1,250 °C. © Springer Science+Business Media, LLC 2011.