• K Sreenivas

      Articles written in Bulletin of Materials Science

    • Enhanced catalytic activity of nanoscale platinum islands loaded onto SnO2 thin film for sensitive LPG gas sensors

      Divya Haridas Vinay Gupta K Sreenivas

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      In the present study, different catalysts (∼ 10 nm thick) including metals, noble metals and metal oxides, were loaded in dotted island form over SnO2 thin film for LPG gas detection. A comparison of various catalysts indicated that the presence of platinum dotted islands over SnO2 thin film deposited by r.f. sputtering exhibited enhanced response characteristics with a high sensitivity, ∼ 742, at an operating temperature of ∼ 280°C. Different characterization techniques have been employed such as atomic force microscopy, X-ray diffraction and UV–vis spectroscopy, to study the surface morphology, grain size and optical properties of the deposited thin films. The results suggest the possibility of utilizing the sensor element with the present novel method of catalyst dispersal for the efficient detection of LPG.

    • Effect of Zr on dielectric, ferroelectric and impedance properties of BaTiO3 ceramic

      Sandeep Mahajan O P Thakur Chandra Prakash K Sreenivas

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      A polycrystalline sample of Zr-doped barium titanate (BaTiO3) was prepared by conventional solid state reaction method. The effect of Zr (0.15) on the structural and microstructural properties of BaTiO3 was investigated by XRD and SEM. The electrical properties (dielectric, ferroelectric and impedance spectroscopy) were measured in wide range of frequency and temperature. With substitutions of Zr, the structure of BaTiO3 changes from tetragonal to rhombohedral. Lattice parameters were found to increase with substitution. The room temperature dielectric constant increases from ∼ 1675 to ∼ 10586 and peak dielectric constant value increases from ∼ 13626 to ∼ 21023 with diffuse phase transition. Impedance spectroscopy reveals the formation of grain and grain boundary in the material and found to decrease with increase in temperature.

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