• A K Poswal

      Articles written in Bulletin of Materials Science

    • Electroless deposition, post annealing and characterization of nickel films on silicon

      Subir Sabharwal Siddharth Palit R B Tokas A K Poswal Sangeeta

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      Electroless deposition of nickel (EN) films on 𝑛-type silicon has been investigated under different process conditions. The interface between the film and substrate has been characterized for electrical properties by probing the contact resistances. X-ray diffraction and atomic force microscopy have been performed to obtain information about the structural and morphological details of the films. As a comparative study, nickel films have also been sputter deposited on silicon substrates. An as-deposited electroless film is observed to form non-ohmic contact while in a sputtered film prepared without the application of substrate heating, the formation of metal–insulating–semiconductor type junction is seen.

    • X-ray absorption spectroscopy of PbMoO4 single crystals

      D Bhattacharyya A K Poswal S N Jha Sangeeta S C Sabharwal

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      X-ray absorption spectra of PbMoO4 (LMO) crystals have been investigated for the first time in literature. The measurements have been carried out at Mo absorption edge at the dispersive EXAFS beamline (BL-8) of INDUS-2 Synchrotron facility at Indore, India. The optics of the beamline was set to obtain a band of 2000 eV at 20,000 eV and the channels of the CCD detector were calibrated by recording the absorption edges of standard Mo and Nb foils in the same setting. The absorption spectra have been measured for three LMO samples prepared under different conditions viz.

      grown in air from stoichiometric starting charge,

      grown in argon from stoichiometric starting charge and

      grown in air from PbO-rich starting charge.

      The results have been explained on the basis of the defect structure analysed in LMO crystals prepared under different conditions. The Mo absorption edge is significantly influenced by the deviations in crystal stoichiometry.

    • EXAFS investigations on PbMoO4 single crystals grown under different conditions

      A K Poswal D Bhattacharyya S N Jha Sangeeta S C Sabharwal

      More Details Abstract Fulltext PDF

      Extended X-ray absorption fine structure (EXAFS) measurements on PbMoO4 (LMO) crystals have been performed at the recently-commissioned dispersive EXAFS beamline (BL-8) of INDUS-2 Synchrotron facility at Indore, India. The LMO samples were prepared under three different conditions viz.

      grown from a stoichiometric starting charge in air ambient,

      grown from a stoichiometric starting charge in argon ambient and

      grown from PbO-rich starting charge in air ambient.

      The EXAFS data obtained at both Pb 𝐿3 and Mo K edges of LMO have been analysed to determine Pb–O, Pb–Mo and Mo–O bond lengths in the crystals. The information thus obtained has been used to examine the microscopic defect structures in crystals grown under different conditions.

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