• P K Biswas

      Articles written in Bulletin of Materials Science

    • Incorporation of cobalt and nickel metal nano-particles in nano-grain zirconia film matrix by solution route

      S Jana P K Biswas

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      Precursor solutions of cobalt/nickel incorporated nano-grain zirconia films were prepared from aquo-organic solutions of zirconium oxychloride octahydrate and corresponding transition metal nitrate. The films were deposited onto silica glass substrate by the dipping technique. Annealing was made at different temperatures from 450°C to 1200°C ± 5°C in air atmosphere. The range of thickness of the films baked at 450°C was 1800–1870 å. For cobalt system Co3O4 was formed initially at 450°C which gradually transformed to alpha cobalt and next to cubic cobalt along with a non-stoichiometric compound (Zr0.71Co0.23O0.06) with increasing annealing temperature. On the other hand, for nickel system nickel metal of nano-size was observed in the nano-grain zirconia film matrix at 450°C. By increasing annealing temperature to 1200°C, a compound, ZrNi4O, was formed which was found to be stable for ∼ 30 days.

    • 3-D mapping with ellipsometrically determined physical thickness/refractive index of spin coated sol–gel silica layer

      S Das P Pal S Roy S Chakraboarty P K Biswas

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      Precursor sol for sol–gel silica layer was prepared from the starting material, tetraethylorthosilicate (TEOS). The sol was deposited onto borosilicate crown (BSC) glass by the spinning technique (rpm 2500). The gel layer thus formed transformed to oxide layer on heating to 450°C for ∼ 30 min. The physical thicknessand the refractive index of the layer were measured ellipsometrically (Rudolph Auto EL II) at 632.8 nm. About 10 × 10 mm surface area of the silica layer was chosen for evaluation of thickness and refractive index values at different points (121 nos.) with 1 mm gap between two points. Those data were utilized in the Autolisp programme for 3-D mapping. Radial distribution of the evaluated values was also displayed.

    • Surface characterization of sol–gel derived indium tin oxide films on glass

      P K Biswas A De L K Dua L Chkoda

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      Indium tin oxide (ITO) films containing different In : Sn atomic ratios, viz. 90 : 10, 70 : 30, 50 : 50, 30 : 70, were deposited on two types of glass substrates by sol–gel spinning technique. XPS analysis of the films was done under as-received and after-sputtering conditions. The narrow spectra obtained for the Na1𝑠, In3𝑑, Sn3𝑑 and O1𝑠 have been discussed. Oxygen was found to exist in three chemical environments in as-received samples due to the existence of

      environmental hydroxyl (–OH) group,

      crystalline ITO and

      amorphous ITO; but it was in two chemical environments, (ii) and (iii), after surface cleaning by sputtering.

      The presence of both tin metal and tin oxides was confirmed by the peak analysis of Sn3𝑑. The In : Sn atomic ratio taken in the precursor sols did not change considerably in the case of developed films of low Sn content, but considerable change was observed in the films having high Sn content.

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