• PRASHANT KUMAR

      Articles written in Journal of Chemical Sciences

    • Preparation of Cu, Ag, Fe and Al nanoparticles by the exploding wire technique

      P Sen Joyee Ghosh Alqudami Abdullah Prashant Kumar Vandana

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      We describe a novel process for the production of nanoparticles of Cu, Ag, Fe and Al which involves exploding their respective wires, triggered by large current densities in the wires. The particles are characterised by X-ray diffraction (XRD) and atomic force microscopy (AFM). Particle sizes in the range 20–100nm were obtained employing this technique. The XRD results reveal that the nanoparticles continue to retain lattice periodicity at reduced particle sizes, displaying in some cases evidence of lattice strain and preferential orientation. In the case of Fe, Mossbauer spectroscopy reveals loss of ferromagnetism as a result of the reduced size of the particles.

    • Role of the solvent medium in the wet-chemical synthesis of CuSbS2, Cu3SbS3, and bismuth substituted Cu3SbS3

      SHALU ATRI MEENAKSHI GUSAIN PRASHANT KUMAR SITHARAMAN UMA RAJAMANI NAGARAJAN

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      Co-thermal decompositions of equimolar concentrations of thiourea complexes ([Cu(tu)3]Cl and [Sb(tu)2]Cl3) in ethylene glycol and ethanolamine were attempted. Based on the results from powder X-ray diffraction, Raman spectroscopy, and energy dispersive spectral analysis of the products, Cu3SbS3 in cubic symmetry emerged from ethylene glycol. In contrast, orthorhombic CuSbS2 resulted from the ethanolamine medium. The generation of copper-rich and copper-poor sulfides was found to be the major reason behind theformation of these stoichiometries of the Cu-Sb-S system as verified by reacting the preformed Cu-S and Sb-S species in ethanolamine and ethylene glycol. Attempts to include bismuth (up to 50 mol%) for antimony were successful only in ethylene glycol medium. The inclusion of bismuth stabilized the orthorhombic form of Cu3SbS3, possibly due to the non-bonded lone pairs present on Bi3+ and Sb3+ -ions. The inclusion of bismuth confirmed from the successful refinement of powder X-ray diffraction pattern by the Rietveld method, Ramanspectroscopy, and energy dispersive spectroscopy analysis. CuSbS22, Cu3SbS3 (cubic) and Cu3Sb0.50Bi0.50S3 showed broad absorption extending up to visible region in their UV-visible spectra. The bandgap values of 1.31, 1.40 and 0.94 eV were estimated by Tauc plots for Cu3SbS3, CuSbS2, and Cu3Sb0.50Bi0.50S3,respectively.

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