• Annu Sharma

      Articles written in Bulletin of Materials Science

    • Synthesis of copper nanoparticles in polycarbonate by ion implantation

      Annu Sharma Suman Bahniwal Sanjeev Aggarwal S Chopra D Kanjilal

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      Copper nanoparticles have been synthesized in polycarbonate by 75 KeV Cu ion implantation with various doses ranging from 6.4 × 1015 to 1.6 × 1017 ions/cm2 with a beam current density of 800 nA/cm2. The composites formed were structurally characterized using Ultraviolet-Visible (UV-Visible) absorption spectroscopy. The appearance of particle plasmon resonance peak, characteristic of copper nanoparticles at 603 nm in absorption spectra of polycarbonate implanted to a dose of 1.6 × 1017 ions/cm2, indicates towards the formation of copper nanoparticles in polycarbonate. Transmission electron microscopy further confirms the formation of copper nanoparticles having size ∼ 3.15 nm. The formation of copper nanoparticles in the layers carbonized by Cu implantation has been discussed. The synthesized copper-polycarbonate nanocomposite has been found to be more conducting than polycarbonate as ascertained using current–voltage characteristics.

    • Tailoring of optical and electrical properties of PMMA by incorporation of Ag nanoparticles


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      Silver–poly(methyl methacrylate) (Ag–PMMA) nanocomposite films were prepared via ex situ chemical routeby employing sodium borohydride (NaBH$_4$) as a reducing agent. In this study, PVP-stabilized Ag nanoparticles were prepared and mixed with PMMA solution. Optical and structural characterizations of resulting nanocomposite films were performedusing UV–visible spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Characteristicsurface plasmon resonance (SPR) peak of Ag nanoparticles was observed at about 3.04 eV (408 nm) in absorptionspectra of Ag–PMMA nanocomposite films. TEM micrograph revealed that the spherical Ag nanoparticles with an averagediameter of $5.4\pm 2.5$ nm are embedded in PMMA. In Raman spectra, besides shifting of vibrational bands, enhancementin intensity of Raman signal with incorporation of Ag nanoparticles was observed. Current ($I$)–voltage ($V$) measurementsrevealed that conductivity of PMMA increased with increasing concentration of Ag nanoparticles. Analysis of $I-V$ datafurther disclosed that at voltage $\lt$2 V, ohmic conduction mechanism is the dominant mechanism, while at voltage $\gt$2 VPoole–Frenkel is the dominant conduction mechanism. Urbach’s energy, the measure of disorder, increased from 0.40 eVfor PMMA to 1.11 eV for Ag–PMMA nanocomposite films containing 0.039 wt% of Ag nanoparticles.

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